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Review

The Relationship Between Chronic Pruritus, Attention-Deficit/Hyperactivity Disorder, and Skin Picking—A Case Series and Narrative Review

by
Eva Loos
1,2,*,
Suzan Sekar
1,
Christiane Rosin
2,
Alexander A. Navarini
1,
Chrysovalandis Schwale
2,
Rainer Schaefert
2,† and
Simon Müller
1,†
1
Department of Dermatology, University Hospital and University of Basel, CH-4031 Basel, Switzerland
2
Department of Psychosomatic Medicine, University Hospital and University of Basel, CH-4031 Basel, Switzerland
*
Author to whom correspondence should be addressed.
†
These authors share last authorship.
J. Clin. Med. 2025, 14(5), 1774; https://doi.org/10.3390/jcm14051774
Submission received: 17 December 2024 / Revised: 19 February 2025 / Accepted: 27 February 2025 / Published: 6 March 2025
(This article belongs to the Special Issue Pruritus and Psyche: An Update on Clinical Management)
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Abstract

:
Chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD) are medical conditions that involve both somatic and psychosocial dimensions, posing unique challenges in clinical management. While CP and SPD are often observed together, the link between ADHD and these conditions is less recognized. This conceptual work describes three women who suffered from a complex interplay of CP, ADHD, and SPD treated at our specialized bi-disciplinary psychodermatological pruritus clinic. Based on our clinical observation and a narrative review of the literature, we assume a bidirectional, triangular relationship between CP, ADHD, and SPD. To support this assumption, we propose two hypotheses: (1) a neurodevelopmental hypothesis, emphasizing that an underlying neurodevelopmental disorder, in this case, ADHD, might present with symptoms like dysfunction of sensory processing, impulsivity, and attention deficits as shared features that reinforce CP and SPD, and (2) a neuroinflammatory hypothesis, suggesting that similar neuroinflammatory signatures promote the co-occurrence of CP, ADHD, and SPD. In addition, we provide specific suggestions derived from our clinical experience on how to manage patients with this complex combination of conditions. Elucidating the interplay between CP, ADHD, and SPD might help develop personalized treatment strategies and improve outcomes.

1. Introduction

Chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD) are medical conditions with a somatic and psychosocial dimension associated with a high burden of disease. More information on the definition, prevalence, etiology, psychosocial aspects, mental comorbidities, and management of these three conditions is provided in Table 1.
Although seemingly disparate, CP, ADHD, and SPD can coexist in our experience, thereby posing a particular treatment challenge. While the association of CP and SPD can often be observed in clinical routine and has been described previously [1,2], the link between ADHD and either of these conditions is less recognized, and rarely described in the medical literature.
In the following, we present three female patients who suffered from a combination of CP, ADHD, and SPD and who were treated in our bi-disciplinary psychodermatological pruritus clinic at the University Hospital of Basel, Switzerland. In these patients, all three conditions seemed to mutually influence each other.
With this report, we aim to do the following:
(1)
Raise awareness of the intricate interaction between CP, ADHD, and SPD;
(2)
Generate hypotheses about the pathophysiological concepts underlying the triangular relationship of these conditions;
(3)
Emphasize the benefits of a bi-disciplinary consultation setting involving dermatologists and mental health specialists and give recommendations from the clinical experience on how to recognize and manage these types of patients.
Table 1. Characteristics of chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD); information in this table refers to adults.
Table 1. Characteristics of chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD); information in this table refers to adults.
Chronic Pruritus (CP) Attention-Deficit/Hyperactivity Disorder (ADHD)Skin Picking Disorder (SPD)
DefinitionPruritus is an unpleasant sensation that provokes the desire to scratch [3]. CP is defined by a duration of
≥6 weeks [4]. 		ADHD is a neurodevelopmental disorder defined and characterized by a persistent pattern of inattention and/or impulsivity and hyperactivity [5]. SPD, also known as excoriation disorder/dermatillomania, is characterized by recurrent and compulsive picking of the skin, despite repeated attempts to stop it [5]. In the ICD-11, SPD falls under the category of bodily focused repetitive behaviors as part of the obsessive–compulsive spectrum.
PrevalenceApprox. 20% of the general population in Western countries during their lifetime [6,7]. Approx. 3% in adults [8].Approx. 4% of the general population, with women being more affected than men [9].
EtiologyCaused by numerous dermatological and non-dermatological diseases (e.g., chronic kidney disease, hepatobiliary disorders, thyroid disease, iron deficiency, polyneuropathy, psychiatric conditions, malignancies, pruritogenic medication) [10].Primarily recognized in childhood and often persisting into adulthood. Underlying factors are not completely understood yet, possibly a combination of genetic predisposition and pre-, peri-, and postnatal environmental factors impacting brain development [11].Results from an urge to find relief from uncomfortable sensations (e.g., itch) or inner tension caused by distress or aversive emotions (e.g., shame, anger, helplessness, anxiety, boredom) [12,13,14].
Psychosocial aspectsHigh psychosocial burden due to distress and impaired quality of life. Excessive scratching and skin manipulation are often accompanied by a pleasurable urge to scratch [15,16], which drives the vicious itch–scratch cycle, thereby aggravating CP. Impaired functioning and quality of life in many areas of life comprising education/profession or social interactions (partner, family, friends). Skin damage, presenting as wounds, crusts, or nodes, can result in distress (e.g., through social stigmatization) and reinforce the picking behavior—even in the absence of cutaneous sensations, such as pruritus or pain.
Mental comorbiditiesInsomnia, depression, anxiety disorders, obsessive–compulsive disorders, somatic symptom disorder, or ADHD [17,18,19,20]. Substance abuse and addiction, affective disorders, eating disorders. Borderline personality disorder is considered to be a possible differential diagnosis [11].Trichotillomania, generalized anxiety disorder, depression, ADHD, obsessive–compulsive disorders [21].
Management(1) General: use of emollients, avoidance of skin dryness, irritants, and stress
(2) Pharmacological: topical and systemic drugs according to current guidelines [10,22]
(3) Non-pharmacological, device-based interventions: e.g., phototherapy, and in selected cases, laser, neurostimulation, cryotherapy, acupuncture [23]		(1) Psychological: psychoeducation, psychotherapy
(2) Pharmacological: stimulants (methylphenidate, amfetamine, lisdexamfetamine)
(3) Neurofeedback [11]		(1) Topical treatment: anti-inflammatory (if the skin is inflamed), itch-relieving emollients, occlusion with bandages or band-aids
(2) Cognitive behavioral therapy (CBT)
(3) Pharmacological: selective serotonin reuptake inhibitors (e.g., fluoxetine, escitalopram), lamotrigine, glutamatergic agents (N-acetylcysteine) [24,25]

2. Case 1

2.1. Patient History

A 53-year-old former bank employee had been suffering from CP for six years without a discernible cause. Initially, she had scratched only when experiencing an itch, but soon after, she began picking and manipulating wound crusts with sharp tools like scissors, knives, or fingernails, even in the absence of an itch. She stated that this behavior stemmed from an irresistible urge to manipulate her skin. This manipulation had a calming effect, as it allowed her to focus on the act of picking, contrasting with her usual inattentive and disorganized nature. As a result of her CP and skin manipulation, she experienced a significantly reduced quality of life. She also reported considerable distress and anxiety related to ongoing family issues. Recently, two of her three children had been diagnosed with ADHD, and she suspected she might have ADHD as well. The patient had a history of panic disorder, for which she had been receiving escitalopram (10 mg/d), but never underwent psychotherapy previously. Prior treatment had consisted of topical corticosteroids, pimecrolimus, polidocanol-containing moisturizers, occasional oral bilastine (20 mg/day), and narrowband ultraviolet B (NB-UVB) phototherapy (three times a week for three months).

2.2. Dermatological and Psychological Assessments

At the first consultation in our joint bi-disciplinary pruritus clinic, quantitative and qualitative itch assessments were performed, along with screening for mental health-related issues, such as depression, anxiety, and somatic distress (refer to Table 2 for an overview of all assessment tools and corresponding scores for each patient). The patient reported a high average itch intensity over the past four weeks and described the itch quality as tickling, burning, and painful, indicative of a neuropathic component of her CP. The itch-related quality of life was reduced according to the German version of the ItchyQoL (GerItchyQoL), a questionnaire assessing the impact of CP on patients’ quality of life (e.g., daily activities, mood, and overall well-being) [26]. She presented with approx. 80 erythematous papules and nodules on her upper and lower extremities, as well as on her back, suggestive of chronic nodular prurigo (CNPG, also referred to as prurigo nodularis). This diagnosis was confirmed by lesional biopsy. The clinical presentation corresponded to an Investigator’s Global Assessment for Chronic Nodular Prurigo (IGA-CNPG) stage 3 (moderate). Of these lesions, more than 75% were excoriated or crusted, reflecting an activity stage 4 (severe) [26]. According to the Erlanger Score (also referred to as Diepgen-Score [27]), a diagnostic tool for evaluating the likelihood of atopic diathesis, there was no evidence of atopic predisposition. A pruritus laboratory screen was conducted according to the European guidelines on CP [10].Remarkable values for all cases are displayed in Table 2.
During the consultation, the patient appeared very stressed by her symptoms and psychosocial burden. She seemed restless, spoke rapidly and excessively, and frequently interrupted the clinicians’ explanations. The patient showed a clinically relevant score in the ADHD self-report questionnaire (ADHS-SB), which assesses ADHD-specific symptomatology (i.e., attention deficits, hyperactivity, and impulsivity) in adults according to DSM-IV, ICD-10 and 11. It is one of five subtests of the German Homburger ADHD Scale for Adults (HASE) [28]. The patient fulfilled the ICD-11 criteria for ADHD. The diagnosis was confirmed by an external psychiatrist specializing in ADHD. Additionally, SPD was diagnosed through further exploration and a high screening score in the modified Skin Picking Scale (mSPS-D), which evaluates the severity of skin picking with regard to, e.g., frequency, intensity, distress, and functional impairment [29]. The patient’s description of manipulation did not suggest any delusional content.

2.3. Applied Treatment and Further Procedures

Skin-directed treatment containing itch-relieving topicals was initiated (refer to Table 2). In addition, the patient participated in several individual in-house cognitive behavioral therapy (CBT) sessions focusing on itch-related aspects. As for ADHD, we started with methylphenidate (10 mg/d). Three weeks later, the patient reported a decreased itch intensity and improved impulse control. The latter may have led to a reduced urge to pick the skin, or it may have improved independently of any change to that urge. Although the patient continued to manipulate her skin in stressful situations, she became more aware of this maladaptive behavior and could process feelings more adaptively. The patient continued to have regular appointments in our clinic, as her symptoms were still not fully under control. In addition to her visits with us, she began external psychotherapy to work on her ADHD- and SPD-related difficulties. All these measures resulted in a significant and durable improvement with almost clear skin (IGA-CNPG severity and activity score ≤1).

3. Case 2

3.1. Patient History

A 69-year-old female artist presented in our clinic with CP persisting for over 10 years. Due to an uncontrollable, automatic urge to scratch, she had developed scarred, nodular, and dyspigmented skin lesions on her lower legs and arms. In addition to the significant itch-related strain, she experienced heightened mental distress due to the feeling of loneliness. The patient had a history of recurrent depressive disorder but never underwent psychopharmacological or psychotherapeutic treatment. She reported having difficulties organizing her appointments, losing track of time during activities, and frequently misplacing or searching for items. She mentioned that several professionals had previously suspected she might have ADHD, but no diagnostic evaluation had been conducted. Dermatological treatments had so far consisted of various topicals including creams containing clobetasol propionate, polidocanol, glycerin, and zinc. A previous lesional skin biopsy had shown spongiotic dermatitis.

3.2. Dermatological and Psychological Assessments

At the first visit to our clinic, the patient reported a moderate average itch intensity over the past four weeks and denied tingling, burning, or prickling itch sensations. Her itch-related quality of life was moderately impaired. She presented with several centimeter-sized, oval, partially excoriated nodules and plaques on her extremities, buttocks, and shoulders, suggestive of CNPG with stage 3 severity (moderate) and stage 4 activity (severe). Laboratory pruritus screening was conducted. During consultation, the patient behaved very restlessly, frequently interrupted conversations, and struggled to focus on medical explanations. She scored above the clinical cut-off on the ADHS-SB. ADHD diagnosis was confirmed by a specialized psychiatrist. She also met the ICD-11 criteria for SPD, with a clinically relevant mSPS-D score. During consultation, the patient reported no current depressive symptoms, which was consistent with the clinical presentation and the screening score (refer to Table 2).

3.3. Applied Treatments and Further Procedures

The patient was treated with itch-relieving topicals (refer to Table 2). Initially, she declined systemic medications including methylphenidate and was unable to adhere to the prescribed topical treatment, partly due to the disorganization associated with her ADHD and partly because of her personal rejection of conventional medicine. Eventually, she agreed to take N-acetylcysteine, which had been reported to have positive effects on SPD [35]. In addition, she received itch-focused in-house CBT. Subsequently, her skin picking subsided, and the skin lesions improved slightly, which the patient perceived as a significant relief. As her symptoms were still not under full control, she continued to have regular appointments at our clinic. The patient rejected starting outpatient psychotherapy. During the 18-month follow-up period, the IGA-CNPG fluctuated between stages 1 and 3, with an activity score ranging between 2 and 3.

4. Case 3

4.1. Patient History

A 51-year-old female unemployed laboratory assistant was referred to us with CP persisting for over two years, primarily affecting her arms and back. The intense itching caused her to scratch until her skin bled, but sometimes she would scratch also in the absence of itching. Furthermore, she reported the frequent urge to manipulate the skin due to “acne” since adolescence. She had been diagnosed with ADHD 20 years ago and had been taking methylphenidate (10 mg/d) ever since. Although this medication was somewhat effective, she continued struggling with ADHD-related symptoms, especially hypersensitivity to external auditory stimuli and impulsivity, the latter resulting in frequent interpersonal conflicts. Due to sleeping problems, she had been prescribed mirtazapine (15 mg/d), which had no positive effects. Previous dermatological treatments included creams containing mometasone 0.1% or polidocanol as well as a few sessions of NB-UVB light, which had not yielded significant improvement.

4.2. Dermatological and Psychological Assessment

The patient reported a high average itch intensity over the past four weeks and a severely reduced itch-related quality of life. The itch quality was described as tickling, painful, and biting. She presented no primary skin lesions, just a few scratch excoriations on her shoulders, lower trunk, and limbs, as well as multiple hypopigmented scars reflecting older, scarred scratch lesions. The laboratory pruritus screen yielded unremarkable results. The skin condition was ultimately determined as CP on primarily non-diseased skin (IFSI II), possibly facilitated by an atopic diathesis (Erlanger Atopy Score: 11/35).
Since the ADHD diagnosis had already been confirmed, no further specific screening was applied. The patient met ICD-11 criteria for SPD, with a clinically relevant value in the mSPS-D.

4.3. Applied Treatments and Further Procedures

Skin-directed treatment consisted of itch-relieving topicals and systemic treatment (refer to Table 2) and NB-UVB phototherapy, which was discontinued after a few sessions as symptoms worsened. Mirtazapine was stopped, due to its lack of benefit on her sleep disturbances, but the patient refused alternative antidepressants. The pre-existing medication with methylphenidate remained unchanged. She was referred to an external psychotherapist specializing in ADHD, where she learned helpful strategies and techniques to reduce ADHD-related symptoms and associated negative psychosocial consequences. During an 11-month follow-up, the itch intensity fluctuated but never reached peaks as high as in the beginning (average 6/10). The patient reported manipulating her skin less often.

5. Discussion

We herein presented three women experiencing a combination of chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD)—conditions that seem to influence each other in a bidirectional manner. Although we see more cases with this combination of conditions in our clinical practice, we chose to focus on the three most salient examples. Nonetheless, a larger patient sample is required to further substantiate the two hypotheses proposed in the following discussion.
The CP-related SPD observed in our patients might have been facilitated by ADHD-associated impaired impulse control. Likewise, attention deficits, as part of the patients’ ADHD, may have led to difficulties adhering to dermatological treatments, thereby worsening CP and SPD. This in turn might have exacerbated ADHD symptoms through itch-related distress and sleep disturbances. That vicious cycle of possible interactions is illustrated in Figure 1.
To our knowledge, the triangular relationship of CP, ADHD, and SPD has not yet been described in the literature, but a few studies indicated that certain bidirectional interactions do exist:
  • Bidirectional relationship between CP and ADHD: Studies have shown that children with atopic dermatitis (AD), a chronic inflammatory skin disease in which CP is a cardinal symptom, are more likely to have comorbid ADHD [36,37,38]. (Neuro)inflammatory processes may play a central role in this interaction. Proinflammatory serum cytokines (proteins serving as signaling molecules within the immune system) released in AD, such as interleukin (IL-)4, IL-6, IL-13, or TNF-α, can cross the blood–brain barrier and potentially interfere with the maturation of prefrontal cortex regions and neurotransmitter systems involved in the pathophysiology of ADHD [39,40,41,42,43]. However, there is limited research on the association between ADHD and other itchy dermatoses, such as psoriasis, urticaria, and prurigo [36]. This may be because AD and ADHD typically manifest during childhood, whereas other forms of CP often emerge later in life when ADHD may be less apparent.
  • Bidirectional relationship between ADHD and SPD: It was hypothesized that the repetitive, compulsive nature of SPD shares similarities with the impulsivity seen in ADHD [44]. ADHD has been previously reported in individuals with SPD, with prevalence rates of ADHD in 8–12% of SPD patients [21,45]. These publications suggest potential shared neurobiological mechanisms between these two disorders; however, they do not elaborate further on potential mechanisms. In addition, these studies were cross-sectional, thereby limiting statements of the causality of temporal relationships. Longitudinal studies are needed to understand the interaction of these disorders over time.
  • Bidirectional relationship between CP and SPD: According to a single-center, cross-sectional study from China, SPD was associated with higher itch intensities and was prevalent in about 65% of patients with AD and about 29% of patients with psoriasis [2]. The authors surmised that the higher rate of SPD in AD reflects the higher prevalence and intensity of CP in these patients. Also, atopic skin might be more prone to react hypersensitively to environmental factors due to an impaired barrier and (latent) inflammation [46]. In turn, the severe itch can be aggravated through exacerbated skin damage caused by SPD, resulting in a perpetuated itch–scratch cycle in which scratch-induced inflammation causes more itching [47].
Combining our clinical observations with these findings from the literature, we propose two hypotheses, (a.) a neurodevelopmental hypothesis and (b.) a neuroinflammatory one, which aim to unify all three conditions through possible common factors.

5.1. Neurodevelopmental Hypothesis

This approach may be grounded in the close connection between skin and psyche, which has been assumed to originate from the shared development of the skin and nervous system from the same embryonic germ layer, the ectoderm [41]. Alterations in neuronal development, as seen in neurodevelopmental disorders like ADHD or autism spectrum disorder, can affect both the central and autonomic nervous systems, as well as the skin. For example, pathologic local alterations of the brain-derived neurotrophic factor levels might have a negative impact both on the development of the prefrontal cortex, which is crucial for executive functions (i.e., cognitive processes that regulate decision-making, behavior, activity level, impulse control, response inhibition, and attention) [48,49], and the morphology of neurons innervating the skin [50]. The combination of neurodevelopmental alterations can lead to (1) sensory processing problems, (2) hyperactivity and impulsivity, and (3) attention deficits, negatively affecting CP and SPD.

5.1.1. Sensory Processing Problems

Sensory processing refers to how the brain actively predicts, organizes, and interprets sensory information from the body. This process allows individuals to generate adaptive responses to sensory information. Individuals with neurodevelopmental alterations typically exhibit dysfunctions in sensory and emotional processing [51,52,53], including altered sensitivity to touch [54]. This may make them more prone to experiencing itch and noticing skin irregularities, such as wounds or crusts, which can result in further scratching and manipulation [13,55]. In patients with ADHD, an unfiltered “sensory overload” may enhance itch sensation and trigger excessive scratching, hence worsening CP [56]. Conversely, the mental distress and sleep disturbances caused by heightened itch can exacerbate symptoms of ADHD [38,57].

5.1.2. Hyperactivity and Impulsivity

In addition to heightened sensory sensitivity, hyperactivity and impulsivity are hallmarks of ADHD. The combination of increased itch sensation and poor impulse control can drive the itch–scratch cycle and, in the long run, lead to SPD. In patients with ADHD, skin manipulation through picking and scratching may serve as a coping mechanism for the distress caused by itch or by aversive emotions [12,13]. The temporary relief through skin picking further reinforces the vicious cycle that exacerbates CP, possibly resulting in secondary skin conditions such as prurigo nodularis or lichen simplex chronicus (IFSI group III), which are characterized by chronic scratch lesions. These lesions can again serve as sensory (and visual) triggers for pathological picking.

5.1.3. Attention Deficits and Other Executive Dysfunctions

Aside from the mentioned impulsivity, deficits in executive functions in ADHD, like attention or response inhibition, can contribute to problems with treatment adherence. Moreover, mindless scratching and picking, especially when these behaviors become habitual [56], can make it even more difficult for patients to notice the skin picking and resist it.
Taken together, these three features seem to be most prominent regarding the skin and may mutually reinforce each other (refer to Figure 2):
  • Sensory processing issues: may result in (hyper)sensitive skin that is more prone to triggers related to CP.
  • Hyperactivity and impulsivity: may result in SPD and certain secondary skin lesions like prurigo nodularis.
  • Attention deficits: may worsen adherence problems regarding dermatological as well as psychotherapeutic interventions.

5.2. Neuroinflammatory Hypothesis

As already suggested for AD, neuroinflammatory cytokines, which mediate inflammation within the nervous system, can cross the blood–brain barrier and lead to changes in the maturation of structural and functional brain structures and neurotransmitter systems, possibly involved in ADHD pathology. For instance, altered levels of certain markers like interleukin (IL)-6, IL-4, IL-17A, and nerve growth factor have been identified as independent risk factors for ADHD in AD [2,41]. Additionally, neuroinflammation in ADHD has been linked to alterations in neurotransmitter systems, including the dopaminergic, serotonergic, and glutamatergic systems, which are sensitive to inflammatory processes [58]. Similarly, AD is characterized by chronic inflammation that can lead to systemic immune activation, potentially influencing neurodevelopmental outcomes [39].
The hypothalamus–pituitary–adrenal axis dysregulation is another common feature. Both AD and ADHD have been associated with altered cortisol responses, indicating a potential role of stress and immune system interactions in the comorbidity of these conditions [59].
Studies have also hypothesized genetic factors; however, in a recent Mendelian randomization analysis, no causal genetic relationship between AD and ADHD was found [60]. The authors of this study hypothesized that previously reported associations between AD and ADHD might have been due to confounding lifestyle factors including psychosocial stress and sleep disturbances. However, there might be similar epigenetic factors influencing neuroinflammation in AD and ADHD, including alterations in DNA methylation, histone modifications, and non-coding RNA regulation, which collectively influence inflammatory pathways and immune dysregulation [61,62,63,64,65,66].
Our two proposed hypotheses aim to shed light on possible pathophysiological concepts underlying the complex relationship between CP, ADHD, and SPD. However, as our observations stem from a non-experimental clinical routine, we cannot draw conclusions about potential causal relationships. This work explores potential links between ADHD, CP, and SPD in the described patient subgroup. While we propose a bidirectional, triangular relationship as a framework, these findings remain correlational and should be interpreted with caution. For instance, ADHD may act as an independent factor or mediator amplifying the itch–scratch cycle through impaired self-regulation and increasing impulsivity.
Concrete suggestions on how to manage patients presenting with a combination of these conditions might be of importance to clinicians. In the following, we therefore provide specific recommendations derived from our clinical experience with this patient group.

5.3. Management of CP, ADHD, and SPD in the Clinical Practice: Challenges and Opportunities

  • Recognize clinical signs: ADHD often goes unrecognized, especially in adult women. In clinical practice, clinicians should look for signs like restlessness, rapid speech, frequent interruptions, and difficulty sustaining attention during consultation. Women with ADHD may also experience anxiety, low self-esteem [67,68], reduced social–emotional well-being, difficulty in relationships, and feelings of a lack of control [69]. Regarding SPD, patients may report an irresistible urge to scratch or manipulate their skin, even in the absence of itch—a key symptom of SPD.
  • Apply screening tools: Most dermatologists lack direct access to mental health professionals. Simple screening tools can help identify comorbidities. Due to the high prevalence of depression and anxiety in CP, screening tools for depression—like the PHQ-8/9 or the Hospital Anxiety and Depression Scale (HADS) [70]—or anxiety—like the GAD-7 or HADS—have been recommended as screening tools [22,71]. As outlined in our work, ADHD and SPD can also be relevant comorbidities of CP that can be screened using the instruments provided in Table 3. However, clinicians should be aware that patients with severe CP may show agitation, overwhelm, and inattentiveness due to pruritus, which could be misinterpreted as ADHD symptoms. After a positive screening, ADHD or SPD should always be confirmed by a respective specialist.
  • Individualize treatment plans and medication: While specific treatment guidelines exist for managing CP, ADHD, and bodily focused repetitive disorders like SPD (refer to Table 1 for references), managing all three conditions together remains challenging. Our three patients required individualized approaches based on unique dynamics and life circumstances. Patients’ adherence but also medication effectiveness varied greatly. ADHD was treated with methylphenidate in patients 1 and 3 (combined with escitalopram in patient 1). While in patient 1 symptoms of ADHD, SPD, and CP subsequently improved, pre-existing long-term treatment with methylphenidate did not prevent CP and SPD in patient 3. Patient 2 refused methylphenidate but showed improvement with N-acetylcysteine (NAC), reducing skin picking and CP, which is in accordance with the previous literature reporting positive effects of NAC on SPD [35,55,72], thereby indirectly benefitting CP through reduced skin damage [73]. Our observations on the inconsistent effects of methylphenidate in patients 1 and 3 align with those of the current literature. So far, two publications found reduced skin picking behavior after treating a 26-year-old woman and a 10-year-old boy, respectively, with methylphenidate [74,75]. This effect was explained by methylphenidate influencing the dopaminergic activity in the prefrontal cortex and striatum regions regulating impulse control and attention. According to another single case report, however, methylphenidate triggered skin picking in a 7-year-old boy with ADHD. Possible explanations for this contradictory finding are not discussed by the authors, however. Due to this scarce information from the medical literature, drawing general conclusions about the effectiveness of methylphenidate on SPD is very limited. Future studies exploring the effect of methylphenidate on SPD in a larger sample are needed.
  • Combine with psychotherapy: Very often, medication alone is insufficient in treating patients with ADHD and/or SPD. Additional psychotherapy helps manage condition-specific symptoms and develop functional coping strategies. Our patients received pruritus-specific, in-house CBT, which has been shown to be effective for CP patients [76]. Two of our patients began outpatient ADHD- and SPD-focused CBT. Psychodynamic therapy may also be helpful in exploring possible underlying functions of maladaptive behavioral patterns. In addition, it should also be mentioned that ADHD and trauma-related disorders show clinical overlap [77,78]. Therefore, bidirectional links between CP, SPD, and other mental disorders are at least conceivable.
  • Address treatment adherence: ADHD-related inattention and disorganization can hinder adherence to treatment regimens, including topical or systemic medications. Offering a simple regimen, being patient, and maintaining an open and trusting patient–doctor relationship can improve treatment adherence.
  • Provide regular follow-up bi-disciplinary consultations: Due to fluctuating severity, influenced by physiological as well as internal and external psychosocial factors, our patients continued regular bi-disciplinary follow-up consultations to discuss treatment options and address or react to new somatic or psychosocial aspects. A collaborative approach of dermatologists and mental health specialists is vital to meet the complex needs of this patient group [79,80]. Our bi-disciplinary setting made our patients feel understood and cared for. Patient 1, for example, found strong relief after receiving an ADHD diagnosis and professional help.

6. Conclusions

Based on our three cases and the discussion above, we believe that there is an intricate interaction between CP, ADHD, and SPD in a subgroup of patients. Each of these conditions stands in a bidirectional relationship with the other two. This concept is supported by the medical literature and may be grounded in neurodevelopmental and neuroinflammatory commonalities. Neurodevelopmental alterations can disrupt sensory processing and executive functions, with (neuro)inflammatory processes possibly playing a central role. Key features include (1) sensory processing problems leading to (hyper)sensitive skin that is prone to CP, (2) hyperactivity and impulsivity manifesting as skin picking, and (3) attention deficits and other executive dysfunctions worsening treatment adherence. Bi-disciplinary collaboration between dermatologists and mental health specialists is therefore crucial for addressing these complex patients.

Author Contributions

Conceptualization, E.L., S.M. and R.S.; Investigation, E.L., S.S. and S.M.; Writing—Original Draft Preparation, E.L., C.R., S.M. and R.S.; Writing—Review and Editing, E.L., S.S., C.R., C.S., A.A.N., S.M. and R.S.; Visualization, E.L., S.M. and R.S.; Supervision, S.M. and R.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Patients provided written research consent to the University Hospital Basel covering the further use of coded, non-genetic, and genetic patient data as well as biological material (samples) in accordance with Art. 29 and 32 of the Human Research Ordinance.

Conflicts of Interest

R.S. received a speaker honorarium from Novartis, is chairman of the Basel Institute for Psychosomatic Medicine and founder and managing director of the Psychosomatic and Psychosocial Services GmbH, which develops and implements psychosomatic and psychosocial training and continuing education programs. All other authors declare that they have no conflicts of interest regarding the contents of this manuscript.

References

  1. Craig-Müller, S.A.; Reichenberg, J.S. The Other Itch That Rashes: A Clinical and Therapeutic Approach to Pruritus and Skin Picking Disorders. Curr. Allergy Asthma Rep. 2015, 15, 31. [Google Scholar] [CrossRef] [PubMed]
  2. Ju, Y.; Li, M.; Lu, X.; Zhao, C.; Zhang, C.; Xie, Z. Skin Picking in Atopic Dermatitis and Psoriasis Patients: A Single-centre Cross-sectional Study in China. Acta Derm. Venereol. 2022, 102, 908. [Google Scholar] [CrossRef] [PubMed]
  3. Savin, J.A. How should we define itching? J. Am. Acad. Dermatol. 1998, 39, 268–269. [Google Scholar] [CrossRef]
  4. Ständer, S.; Weisshaar, E.; Mettang, T.; Szepietowski, J.; Carstens, E.; Ikoma, A.; Bergasa, N.; Gieler, U.; Misery, L.; Wallengren, J.; et al. Clinical Classification of Itch: A Position Paper of the International Forum for the Study of Itch. Acta Derm. Venereol. 2007, 87, 291–294. [Google Scholar] [CrossRef] [PubMed]
  5. World Health Organization. International Classification of Diseases Eleventh Revision (ICD-11); World Health Organization: Geneva, Switzerland, 2022. [Google Scholar]
  6. Butler, D.C.; Berger, T.; Elmariah, S.; Kim, B.; Chisolm, S.; Kwatra, S.G.; Mollanazar, N.; Yosipovitch, G. Chronic Pruritus: A Review. JAMA 2024, 331, 2114–2124. [Google Scholar] [CrossRef]
  7. Ständer, S.; Schäfer, I.; Phan, N.Q.; Blome, C.; Herberger, K.; Heigel, H.; Augustin, M. Prevalence of Chronic Pruritus in Germany: Results of a Cross-Sectional Study in a Sample Working Population of 11,730. Dermatology 2010, 221, 229–235. [Google Scholar] [CrossRef]
  8. Simon, V.; Czobor, P.; Bálint, S.; Mészáros, A.; Bitter, I. Prevalence and correlates of adult attention-deficit hyperactivity disorder: Meta-analysis. Br. J. Psychiatry 2009, 194, 204–211. [Google Scholar] [CrossRef]
  9. Farhat, L.C.; Reid, M.; Bloch, M.H.; Olfson, E. Prevalence and gender distribution of excoriation (skin-picking) disorder: A systematic review and meta-analysis. J. Psychiatr. Res. 2023, 161, 412–418. [Google Scholar] [CrossRef]
  10. Weisshaar, E.; Szepietowski, J.C.; Dalgard, F.J.; Garcovich, S.; Gieler, U.; Gimenez-Arnau, A.M.; Lambert, J.; Leslie, T.; Mettang, T.; Misery, L.; et al. European S2k Guideline on Chronic Pruritus. 2019. Available online: https://publicatt.unicatt.it/handle/10807/168850 (accessed on 19 July 2024).
  11. AWMF. Long Version of the Interdisciplinary, Evidence-and Consensus-Based (S3) Guidelines ‘Attention Deficit Hyperactivity Disorder (ADHD) in Children, Adolescents and Adults’. AWMF-Registernummer 028-045. 2017. Available online: https://register.awmf.org/assets/guidelines/028_D_G_f_Kinder-_und_Jugendpsychiatrie_und_-psychotherapie/028-045eng_S3_ADHS_2020-12-abgelaufen.pdf (accessed on 24 November 2024).
  12. Anderson, S.; Clarke, V.; Thomas, Z. The problem with picking: Permittance, escape and shame in problematic skin picking. Psychol. Psychother. Theory Res. Pract. 2023, 96, 83–100. [Google Scholar] [CrossRef]
  13. Torales, J.; Díaz, N.R.; Barrios, I.; Navarro, R.; García, O.; O’Higgins, M.; Castaldelli-Maia, J.M.; Ventriglio, A.; Jafferany, M. Psychodermatology of skin picking (excoriation disorder): A comprehensive review. Dermatol. Ther. 2020, 33, e13661. [Google Scholar] [CrossRef]
  14. Snorrason, Í.; Smári, J.; Ólafsson, R.P. Emotion regulation in pathological skin picking: Findings from a non-treatment seeking sample. J. Behav. Ther. Exp. Psychiatry 2010, 41, 238–245. [Google Scholar] [CrossRef] [PubMed]
  15. Golpanian, R.S.; Fourzali, K.; Fowler, E.; Kursewicz, C.D.; Lipman, Z.; Chan, Y.H.; Yosipovitch, G. The Pleasurability of Scratching an Itch Amongst Different Pruritic Conditions. Acta Derm. Venereol. 2020, 100, 5854. [Google Scholar] [CrossRef] [PubMed]
  16. Papoiu, A.D.P.; Nattkemper, L.A.; Sanders, K.M.; Kraft, R.A.; Chan, Y.-H.; Coghill, R.C.; Yosipovitch, G. Brain’s Reward Circuits Mediate Itch Relief. A Functional MRI Study of Active Scratching. PLoS ONE 2013, 8, e82389. [Google Scholar] [CrossRef] [PubMed]
  17. Cole, E.F.; Ojeaga, A.; Chen, S.; Swerlick, R.A. Symptoms of depression and anxiety are associated with poorer functional outcomes in chronic pruritus. J. Am. Acad. Dermatol. 2021, 85, 730–731. [Google Scholar] [CrossRef]
  18. Lee, J.; Suh, H.; Jung, H.; Park, M.; Ahn, J. Association between chronic pruritus, depression, and insomnia: A cross-sectional study. JAAD Int. 2021, 3, 54–60. [Google Scholar] [CrossRef]
  19. Schneider, G.; Grebe, A.; Bruland, P.; Heuft, G.; Ständer, S. Chronic pruritus patients with psychiatric and psychosomatic comorbidity are highly burdened: A longitudinal study. J. Eur. Acad. Dermatol. Venereol. 2019, 33, e288–e291. [Google Scholar] [CrossRef]
  20. Zeidler, C.; Kupfer, J.; Dalgard, F.J.; Bewley, A.; Evers, A.W.M.; Gieler, U.; Lien, L.; Sampogna, F.; Tomas Aragones, L.; Vulink, N.; et al. Dermatological patients with itch report more stress, stigmatization experience, anxiety and depression compared to patients without itch: Results from a European multi-centre study. J. Eur. Acad. Dermatol. Venereol. 2024, 38, 1649–1661. [Google Scholar] [CrossRef]
  21. Grant, J.E.; Chamberlain, S.R. Characteristics of 262 adults with skin picking disorder. Compr. Psychiatry 2022, 117, 152338. [Google Scholar] [CrossRef]
  22. Ständer, S.; Zeidler, C.; Augustin, M.; Darsow, U.; Kremer, A.E.; Legat, F.J.; Koschmieder, S.; Kupfer, J.; Mettang, T.; Metz, M.; et al. S2k guideline: Diagnosis and treatment of chronic pruritus. JDDG J. Dtsch. Dermatol. Ges. 2022, 20, 1387–1402. [Google Scholar] [CrossRef]
  23. Zhu, J.; Zhao, X.; Navarini, A.A.; Mueller, S.M. Device-based physical therapies in chronic pruritus: A narrative review. J. Am. Acad. Dermatol. 2024, 91, 699–705. [Google Scholar] [CrossRef]
  24. Lochner, C.; Roos, A.; Stein, D.J. Excoriation (skin-picking) disorder: A systematic review of treatment options. Neuropsychiatr. Dis. Treat. 2017, 13, 1867–1872. [Google Scholar] [CrossRef]
  25. Schumer, M.C.; Bartley, C.A.; Bloch, M.H. Systematic Review of Pharmacological and Behavioral Treatments for Skin Picking Disorder. J. Clin. Psychopharmacol. 2016, 36, 147. [Google Scholar] [CrossRef]
  26. Zeidler, C.; Pereira, M.P.; Augustin, M.; Spellman, M.; Ständer, S. Investigator’s Global Assessment of Chronic Prurigo: A New Instrument for Use in Clinical Trials. Acta Derm. Venereol. 2021, 101, adv00401. [Google Scholar] [CrossRef]
  27. Diepgen, T.L.; Sauerbrei, W.; Fartasch, M. Development and validation of diagnostic scores for atopic dermatitis incorporating criteria of data quality and practical usefulness. J. Clin. Epidemiol. 1996, 49, 1031–1038. [Google Scholar] [CrossRef]
  28. Schmidt, S.; Petermann, F. Testbesprechung: Homburger ADHS-Skalen für Erwachsene (HASE). Z. Für Psychiatr. Psychol. Und Psychother. 2008, 56, 155–159. [Google Scholar] [CrossRef]
  29. Krause, K.; Kessler, B.; Weller, K.; Veidt, J.; Chen, S.C.; Martus, P.; Church, M.K.; Metz, M.; Maurer, M. German version of ItchyQoL: Validation and initial clinical findings. Acta Derm. Venereol. 2013, 93, 562–568. [Google Scholar] [CrossRef]
  30. Mehrmann, L.M.; Hunger, A.; Gerlach, A.L. Pathologisches Hautzupfen/-quetschen (Skin Picking). Z. Klin. Psychol. Psychother. 2017, 46, 23–31. [Google Scholar] [CrossRef]
  31. Kroenke, K.; Strine, T.W.; Spitzer, R.L.; Williams, J.B.W.; Berry, J.T.; Mokdad, A.H. The PHQ-8 as a measure of current depression in the general population. J. Affect. Disord. 2009, 114, 163–173. [Google Scholar] [CrossRef]
  32. Spitzer, R.L.; Kroenke, K.; Williams, J.B.W.; Löwe, B. A Brief Measure for Assessing Generalized Anxiety Disorder: The GAD-7. Arch. Intern. Med. 2006, 166, 1092. [Google Scholar] [CrossRef]
  33. Gierk, B.; Kohlmann, S.; Kroenke, K.; Spangenberg, L.; Zenger, M.; Brähler, E.; Löwe, B. The Somatic Symptom Scale–8 (SSS-8): A Brief Measure of Somatic Symptom Burden. JAMA Intern. Med. 2014, 174, 399. [Google Scholar] [CrossRef]
  34. Linde, K.; Riedl, B.; Kehrer, S.; Schneider, A.; Löwe, B.; Toussaint, A. Der Fragebogen SSD-12 zur Erfassung der Psychischen Belastung bei Somatischer Belastungsstörung—Erste Erfahrungen und Validierung bei Hausarztpatienten. 51 Kongress für Allgemeinmedizin und Familienmedizin. 5 September 2017. Available online: http://www.egms.de/en/meetings/degam2017/17degam143.shtml (accessed on 26 July 2024).
  35. Grant, J.E.; Chamberlain, S.R.; Redden, S.A.; Leppink, E.W.; Odlaug, B.L.; Kim, S.W. N-Acetylcysteine in the Treatment of Excoriation Disorder: A Randomized Clinical Trial. JAMA Psychiatry 2016, 73, 490–496. [Google Scholar] [CrossRef]
  36. Cheng, Y.; Lu, J.-W.; Wang, J.-H.; Loh, C.-H.; Chen, T.-L. Associations of Atopic Dermatitis with Attention Deficit/Hyperactivity Disorder and Autism Spectrum Disorder: A Systematic Review and Meta-Analysis. Dermatology 2023, 240, 13–25. [Google Scholar] [CrossRef]
  37. Nygaard, U.; Riis, J.L.; Deleuran, M.; Vestergaard, C. Attention-Deficit/Hyperactivity Disorder in Atopic Dermatitis: An Appraisal of the Current Literature. Pediatr. Allergy Immunol. Pulmonol. 2016, 29, 181–188. [Google Scholar] [CrossRef]
  38. Strom, M.A.; Fishbein, A.B.; Paller, A.S.; Silverberg, J.I. Association between atopic dermatitis and attention deficit hyperactivity disorder in U.S. children and adults. Br. J. Dermatol. 2016, 175, 920–929. [Google Scholar] [CrossRef]
  39. Buske-Kirschbaum, A.; Schmitt, J.; Plessow, F.; Romanos, M.; Weidinger, S.; Roessner, V. Psychoendocrine and psychoneuroimmunological mechanisms in the comorbidity of atopic eczema and attention deficit/hyperactivity disorder. Psychoneuroendocrinology 2013, 38, 12–23. [Google Scholar] [CrossRef]
  40. van der Schans, J.; Çiçek, R.; de Vries, T.W.; Hak, E.; Hoekstra, P.J. Association of atopic diseases and attention-deficit/hyperactivity disorder: A systematic review and meta-analyses. Neurosci. Biobehav. Rev. 2017, 74, 139–148. [Google Scholar] [CrossRef]
  41. Jameson, C.; Boulton, K.A.; Silove, N.; Nanan, R.; Guastella, A.J. Ectodermal origins of the skin-brain axis: A novel model for the developing brain, inflammation, and neurodevelopmental conditions. Mol. Psychiatry 2023, 28, 108–117. [Google Scholar] [CrossRef]
  42. Cameron, S.; Donnelly, A.; Broderick, C.; Arichi, T.; Bartsch, U.; Dazzan, P.; Elberling, J.; Godfrey, E.; Gringras, P.; Heathcote, L.C.; et al. Mind and skin: Exploring the links between inflammation, sleep disturbance and neurocognitive function in patients with atopic dermatitis. Allergy 2024, 79, 26–36. [Google Scholar] [CrossRef]
  43. Chang, S.-J.; Kuo, H.-C.; Chou, W.-J.; Tsai, C.-S.; Lee, S.-Y.; Wang, L.-J. Cytokine Levels and Neuropsychological Function among Patients with Attention-Deficit/Hyperactivity Disorder and Atopic Diseases. J. Pers. Med. 2022, 12, 1155. [Google Scholar] [CrossRef]
  44. Redden, S.A.; Leppink, E.W.; Grant, J.E. Body focused repetitive behavior disorders: Significance of family history. Compr. Psychiatry 2016, 66, 187–192. [Google Scholar] [CrossRef]
  45. Lin, A.; Farhat, L.C.; Flores, J.M.; Levine, J.L.S.; Fernandez, T.V.; Bloch, M.H.; Olfson, E. Characteristics of trichotillomania and excoriation disorder across the lifespan. Psychiatry Res. 2023, 322, 115120. [Google Scholar] [CrossRef]
  46. Leung, D.Y. New Insights into Atopic Dermatitis: Role of Skin Barrier and Immune Dysregulation. Allergol. Int. 2013, 62, 151–161. [Google Scholar] [CrossRef]
  47. Mack, M.R.; Kim, B.S. The Itch–Scratch Cycle: A Neuroimmune Perspective. Trends Immunol. 2018, 39, 980–991. [Google Scholar] [CrossRef]
  48. Wong, J.; Webster, M.J.; Cassano, H.; Weickert, C.S. Changes in alternative brain-derived neurotrophic factor transcript expression in the developing human prefrontal cortex. Eur. J. Neurosci. 2009, 29, 1311–1322. [Google Scholar] [CrossRef]
  49. Komori, T.; Okamura, K.; Ikehara, M.; Yamamuro, K.; Endo, N.; Okumura, K.; Yamauchi, T.; Ikawa, D.; Ouji-Sageshima, N.; Toritsuka, M.; et al. Brain-derived neurotrophic factor from microglia regulates neuronal development in the medial prefrontal cortex and its associated social behavior. Mol. Psychiatry 2024, 29, 1338–1349. [Google Scholar] [CrossRef]
  50. Raap, U.; Goltz, C.; Deneka, N.; Bruder, M.; Renz, H.; Kapp, A.; Wedi, B. Brain-derived neurotrophic factor is increased in atopic dermatitis and modulates eosinophil functions compared with that seen in nonatopic subjects. J. Allergy Clin. Immunol. 2005, 115, 1268–1275. [Google Scholar] [CrossRef]
  51. Collins, M.; Grant, J.E. Sensory processing in skin picking disorder. J. Obs. Compuls. Relat. Disord. 2024, 41, 100870. [Google Scholar] [CrossRef]
  52. Grossman, A.; Avital, A. Emotional and sensory dysregulation as a possible missing link in attention deficit hyperactivity disorder: A review. Front. Behav. Neurosci. 2023, 17, 1118937. [Google Scholar] [CrossRef]
  53. Alexander, J.R.; Houghton, D.C.; Bauer, C.C.; Lench, H.C.; Woods, D.W. Emotion regulation deficits in persons with body-focused repetitive behavior disorders. J. Affect. Disord. 2018, 227, 463–470. [Google Scholar] [CrossRef]
  54. Schaffler, M.D.; Middleton, L.J.; Abdus-Saboor, I. Mechanisms of Tactile Sensory Phenotypes in Autism: Current Understanding and Future Directions for Research. Curr. Psychiatry Rep. 2019, 21, 134. [Google Scholar] [CrossRef]
  55. Jafferany, M.; Patel, A. Skin-Picking Disorder: A Guide to Diagnosis and Management. CNS Drugs 2019, 33, 337–346. [Google Scholar] [CrossRef]
  56. Parsa, L.; Pixley, J.N.; Fried, R.G. “Pick” wisely: An approach to diagnosis and management of pathologic skin picking. Clin. Dermatol. 2023, 41, 41–48. [Google Scholar] [CrossRef]
  57. Kruse, L.; Cices, A.; Fishbein, A.B.; Paller, A.S. Neurocognitive function in moderate–severe pediatric atopic dermatitis: A case–control study. Pediatr. Dermatol. 2019, 36, 110–114. [Google Scholar] [CrossRef]
  58. Dunn, G.A.; Nigg, J.T.; Sullivan, E.L. Neuroinflammation as a risk factor for attention deficit hyperactivity disorder. Pharmacol. Biochem. Behav. 2019, 182, 22–34. [Google Scholar] [CrossRef]
  59. Buske-Kirschbaum, A.; Trikojat, K.; Tesch, F.; Schmitt, J.; Roessner, V.; Luksch, H.; Rösen-Wolff, A.; Plessow, F. Altered hypothalamus-pituitary-adrenal axis function: A relevant factor in the comorbidity of atopic eczema and attention deficit/hyperactivity disorder? Psychoneuroendocrinology 2019, 105, 178–186. [Google Scholar] [CrossRef]
  60. Ng, W.; Loh, M.; Yew, Y.W. Investigating causal relationships between genetically determined increased risk of attention-deficit/hyperactivity disorder (ADHD) and atopic dermatitis (AD): A Mendelian randomization analysis. Exp. Dermatol. 2023, 32, 1468–1475. [Google Scholar] [CrossRef]
  61. Acevedo, N.; Benfeitas, R.; Katayama, S.; Bruhn, S.; Andersson, A.; Wikberg, G.; Lundeberg, L.; Lindvall, J.M.; Greco, D.; Kere, J.; et al. Epigenetic alterations in skin homing CD4+CLA+ T cells of atopic dermatitis patients. Sci. Rep. 2020, 10, 18020. [Google Scholar] [CrossRef]
  62. Chua, R.X.Y.; Tay, M.J.Y.; Ooi, D.S.Q.; Siah, K.T.H.; Tham, E.H.; Shek, L.P.-C.; Meaney, M.J.; Broekman, B.F.P.; Loo, E.X.L. Understanding the Link Between Allergy and Neurodevelopmental Disorders: A Current Review of Factors and Mechanisms. Front. Neurol. 2020, 11, 603571. [Google Scholar] [CrossRef]
  63. Vázquez-González, D.; Carreón-Trujillo, S.; Alvarez-Arellano, L.; Abarca-Merlin, D.M.; Domínguez-López, P.; Salazar-García, M.; Corona, J.C. A Potential Role for Neuroinflammation in ADHD. Adv. Exp. Med. Biol. 2023, 1411, 327–356. [Google Scholar] [CrossRef]
  64. da Silva Duarte, A.J.; Sanabani, S.S. Deciphering epigenetic regulations in the inflammatory pathways of atopic dermatitis. Life Sci. 2024, 348, 122713. [Google Scholar] [CrossRef]
  65. Akhtar, S.; Alsayed, R.K.M.E.; Ahmad, F.; AlHammadi, A.; Al-Khawaga, S.; AlHarami, S.M.A.M.; Alam, M.A.; Al Naama, K.A.H.N.; Buddenkotte, J.; Uddin, S.; et al. Epigenetic control of inflammation in Atopic Dermatitis. Semin. Cell Dev. Biol. 2024, 154, 199–207. [Google Scholar] [CrossRef]
  66. Eapen, A.A.; Parameswaran, S.; Forney, C.; Edsall, L.E.; Miller, D.; Donmez, O.; Dunn, K.; Lu, X.; Granitto, M.; Rowden, H.; et al. Epigenetic and transcriptional dysregulation in CD4+ T cells in patients with atopic dermatitis. PLoS Genet. 2022, 18, e1009973. [Google Scholar] [CrossRef]
  67. Quinn, P.O.; Madhoo, M. A Review of Attention-Deficit/Hyperactivity Disorder in Women and Girls: Uncovering This Hidden Diagnosis. Prim. Care Companion CNS Disord. 2014, 16, 27250. [Google Scholar] [CrossRef]
  68. Young, S.; Adamo, N.; Ásgeirsdóttir, B.B.; Branney, P.; Beckett, M.; Colley, W.; Cubbin, S.; Deeley, Q.; Farrag, E.; Gudjonsson, G.; et al. Females with ADHD: An expert consensus statement taking a lifespan approach providing guidance for the identification and treatment of attention-deficit/hyperactivity disorder in girls and women. BMC Psychiatry 2020, 20, 404. [Google Scholar] [CrossRef]
  69. Attoe, D.E.; Climie, E.A. Miss. Diagnosis: A Systematic Review of ADHD in Adult Women. J. Atten. Disord. 2023, 27, 645–657. [Google Scholar] [CrossRef]
  70. Zigmond, A.S.; Snaith, R.P. The Hospital Anxiety and Depression Scale. Acta Psychiatr. Scand. 1983, 67, 361–370. [Google Scholar] [CrossRef]
  71. Ständer, S.; Pereira, M.P.; Berger, T.; Zeidler, C.; Augustin, M.; Bobko, S.; Brenaut, E.; Chen, S.C.; Chisolm, S.; Dalgard, F.J.; et al. IFSI-guideline on chronic prurigo including prurigo nodularis. Itch 2020, 5, e42. [Google Scholar] [CrossRef]
  72. Silva-Netto, R.; Jesus, G.; Nogueira, M.; Tavares, H. N-acetylcysteine in the treatment of skin-picking disorder. Braz. J. Psychiatry 2014, 36, 101. [Google Scholar] [CrossRef]
  73. Adil, M.; Amin, S.S.; Mohtashim, M. N-acetylcysteine in dermatology. Indian. J. Dermatol. Venereol. Leprol. 2018, 84, 652. [Google Scholar] [CrossRef]
  74. Bernardes, C.; Mattos, P.; Nazar, B.P. Skin picking disorder comorbid with ADHD successfully treated with methylphenidate. Braz. J. Psychiatry 2018, 40, 111. [Google Scholar] [CrossRef]
  75. Çolak Sivri, R.; Çolak, B. Cessation of Skin Picking Symptoms With Methylphenidate Treatment in a Child With Comorbid Skin Picking and Attention-Deficit/Hyperactivity Disorder. Clin. Neuropharmacol. 2019, 42, 105. [Google Scholar] [CrossRef] [PubMed]
  76. Schut, C.; Mollanazar, N.; Kupfer, J.; Gieler, U.; Yosipovitch, G. Psychological Interventions in the Treatment of Chronic Itch. Acta Derm. Venereol. 2015, 96, 157–161. [Google Scholar] [CrossRef] [PubMed]
  77. Knight, A.R.; Kim, S.; Currao, A.; Lebas, A.; Nowak, M.K.; Milberg, W.P.; Fortier, C.B. Assessing Attention-Deficit/Hyperactivity Disorder in Post-9/11 Veterans: Prevalence, Measurement Correspondence, and Comorbidity With Posttraumatic Stress Disorder. Mil. Med. 2024, usae539. [Google Scholar] [CrossRef]
  78. Martínez, L.; Prada, E.; Satler, C.; Tavares, M.C.H.; Tomaz, C. Executive Dysfunctions: The Role in Attention Deficit Hyperactivity and Post-traumatic Stress Neuropsychiatric Disorders. Front. Psychol. 2016, 7, 1230. [Google Scholar] [CrossRef] [PubMed]
  79. Marshall, C.; Taylor, R.; Bewley, A. Psychodermatology in Clinical Practice: Main Principles. Acta Derm. Venereol. 2016, 96, 30–34. [Google Scholar] [CrossRef]
  80. Misery, L.; Chastaing, M. Joint Consultation by a Psychiatrist and a Dermatologist. Dermatol. Psychosom. Dermatol. Psychosom. 2003, 4, 160–164. [Google Scholar] [CrossRef]
  81. Ustun, B.; Adler, L.A.; Rudin, C.; Faraone, S.V.; Spencer, T.J.; Berglund, P.; Gruber, M.J.; Kessler, R.C. The World Health Organization Adult Attention-Deficit/Hyperactivity Disorder Self-Report Screening Scale for DSM-5. JAMA Psychiatry 2017, 74, 520–526. [Google Scholar] [CrossRef]
  82. Snorrason, I.; Ólafsson, R.P.; Flessner, C.A.; Keuthen, N.J.; Franklin, M.E.; Woods, D.W. The Skin Picking Scale-Revised: Factor structure and psychometric properties. J. Obs. Compuls. Relat. Disord. 2012, 1, 133–137. [Google Scholar] [CrossRef]
  83. Keuthen, N.J.; Deckersbach, T.; Wilhelm, S.; Engelhard, I.; Forker, A.; O’sullivan, R.L.; Jenike, M.A.; Baer, L. The Skin Picking Impact Scale (SPIS): Scale Development and Psychometric Analyses. Psychosomatics 2001, 42, 397–403. [Google Scholar] [CrossRef]
  84. Ballmann, C.; Kölle, M.A.; Bekavac-Günther, I.; Wolf, F.; Pargent, F.; Barzel, A.; Philipsen, A.; Gensichen, J. Evaluation of the German Version of the Adult Attention-Deficit/Hyperactivity Disorder Self-Report Screening Scale for DSM-5 as a Screening Tool for Adult Attention-Deficit/Hyperactivity Disorder in Primary Care. Front. Psychol. 2022, 13, 858147. [Google Scholar] [CrossRef]
  85. Snorrason, I.; Keuthen, N.J.; Lee, H.-J.; Beard, C.; Björgvinsson, T. Skin Picking Scale-Revised: Diagnostic accuracy and optimal cut-off scores in university and psychiatric settings. J. Obs. Compuls. Relat. Disord. 2022, 34, 100743. [Google Scholar] [CrossRef]
Jcm 14 01774 g001
Figure 1. Suggested bidirectional, triangular relationship between chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD) as observed in our three female cases. a e.g., fatigue, anxiety, irritability, avoidance, worrying, social withdrawal; b e.g., interleukin (IL)-6, IL-4, IL-17A, nerve growth factor; c e.g., hypo-/hyper-responsiveness of touch, clothing, external irritants (cosmetics, disinfectants, detergents); d e.g., inflammation, crusts as observed in prurigo nodularis or lichen simplex chronicus; e e.g., interpersonal conflicts (e.g., family, job), stigmatization, avoidance behavior.
Figure 1. Suggested bidirectional, triangular relationship between chronic pruritus (CP), attention-deficit/hyperactivity disorder (ADHD), and skin picking disorder (SPD) as observed in our three female cases. a e.g., fatigue, anxiety, irritability, avoidance, worrying, social withdrawal; b e.g., interleukin (IL)-6, IL-4, IL-17A, nerve growth factor; c e.g., hypo-/hyper-responsiveness of touch, clothing, external irritants (cosmetics, disinfectants, detergents); d e.g., inflammation, crusts as observed in prurigo nodularis or lichen simplex chronicus; e e.g., interpersonal conflicts (e.g., family, job), stigmatization, avoidance behavior.
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Figure 2. Proposed neurodevelopmental hypothesis. Attention-deficit/hyperactivity disorder (ADHD) as a neurodevelopmental disorder may result in difficulties with sensory processing and executive functions, like hyperactivity and impulsivity as well as attention deficits, which reinforce chronic pruritus (CP) and skin picking disorder (SPD).
Figure 2. Proposed neurodevelopmental hypothesis. Attention-deficit/hyperactivity disorder (ADHD) as a neurodevelopmental disorder may result in difficulties with sensory processing and executive functions, like hyperactivity and impulsivity as well as attention deficits, which reinforce chronic pruritus (CP) and skin picking disorder (SPD).
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Table 2. Overview of the three cases regarding patient characteristics, diagnoses, individual scores from applied quantitative and qualitative itch-related assessments and mental health-related screenings (German versions), and newly initiated treatment.
Table 2. Overview of the three cases regarding patient characteristics, diagnoses, individual scores from applied quantitative and qualitative itch-related assessments and mental health-related screenings (German versions), and newly initiated treatment.
RangeCase 1Case 2Case 3
Sex FemaleFemaleFemale
Age (years) 536951
Diagnoses
Chronic Pruritus (CP)-✓ (IFSI III)✓ (IFSI III)✓ (IFSI II)
Attention-Deficit/Hyperactivity Disorder (ADHD)-✓✓✓
Skin Picking Disorder (SPD)-✓✓✓
Pruritus-specific Assessments
Duration of CP (Years)-6102
Mean Itch Intensity (Past 4 Weeks):
Numeric Rating Scale (NRS) 		0–107 5 8
Itch-related Quality of Life: GerItchyQoL 0–110 75 57 85
Laboratory Pruritus Screen
(According to [10])		 - Total IgE: 340 kIU/L, otherwise unremarkableTotal IgE: 490 kIU/L, Inhalation screen: sx1: 2.63 kIU/LTSH: 5.57 mIU/L
Mental Health-specific Assessments
ADHD: Not applied due to already confirmed diagnosis.
ADHS-SB 0–66 25 35
Skin Picking:
mSPS-D 0–36 26 20 18
Depression:
PHQ-80–247015
Anxiety:
GAD-70–21459
Somatic Burden:
SSS-80–327123
SSD-120–48221640
Newly Initiated Treatment
Dermatological -Topical: mometasone (0.1%), pimecrolimus, polidocanol
Systemic: hydroxyzine (25 mg/d, in the evening)		Topical: polidocanol and clobetasol (0.5 mg/g)
Systemic: N-acetylcysteine (600 mg, twice/d)		Topical: mometasone (0.1%), polidocanol
Systemic: bilastine (20 mg)
Device-based: NB-UVB light therapy
Mental -Pharmacological: methylphenidate (5 mg/d), escitalopram (10 mg/d)
Psychotherapy:
in-house and external CBT		Pharmacological: none
Psychotherapy:
in-house CBT		Pharmacological: methylphenidate (10 mg/d)
Psychotherapy:
in-house and external CBT
Abbr.: ADHS-SB: ADHD self-report questionnaire, taken from the German Homburger ADHD Scale for Adults (HASE) [28]; CBT: cognitive behavioral therapy; IFSI: International Forum for the Study of Itch [4]. GerItchyQoL: German version of the ItchyQoL [29]; mSPS-D: modified version of the Skin Picking Scale [30]; PHQ-8: Patient Health Questionnaire with 8 items [31]; GAD-7: General Anxiety Disorder questionnaire [32]; SSS-8: Somatic Severity Scale [33]; SSD-12: Somatic Symptom Disorder Criteria B-scale [34].
Table 3. Possible screening instruments for attention-deficit/hyperactivity disorder (ADHD) and skin picking disorder (SPD).
Table 3. Possible screening instruments for attention-deficit/hyperactivity disorder (ADHD) and skin picking disorder (SPD).
ADHDSPD
InstrumentAdult ADHD Self-Report Scale (ASRS-5)
[81]		Skin Picking Scale-Revised (SPS-R)
[82]		Skin Picking Impact Scale (SPIS)
[83]
German versionGerman version by Ballmann and colleagues [84].Modified German version (mSPS-D) by Mehrmann and colleagues [30].German version (SPIS-D) by Mehrmann and colleagues [30].
DescriptionAssesses with DSM-5 criteria for ADHD. Can be used in primary care and other non-specialist settings.Assesses the frequency, intensity, and burden of SPD.Assesses psychosocial impairment caused by skin picking.
Number of items, rangeGerman ASRS-5: 6, 0–30mSPS-D: 9, 0–36SPIS-D: 4, 0–16
Clinical cut-offPositive screening for ADHD with a clinical cut-off of ≥14.For the original version: clinical cut-off of 9 [85]. So far, no official cut-off scores exist for the German version.For the original version: clinical cut-off of 7 [83]. So far, no official cut-off scores exist for the German version.
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Loos, E.; Sekar, S.; Rosin, C.; Navarini, A.A.; Schwale, C.; Schaefert, R.; Müller, S. The Relationship Between Chronic Pruritus, Attention-Deficit/Hyperactivity Disorder, and Skin Picking—A Case Series and Narrative Review. J. Clin. Med. 2025, 14, 1774. https://doi.org/10.3390/jcm14051774

AMA Style

Loos E, Sekar S, Rosin C, Navarini AA, Schwale C, Schaefert R, Müller S. The Relationship Between Chronic Pruritus, Attention-Deficit/Hyperactivity Disorder, and Skin Picking—A Case Series and Narrative Review. Journal of Clinical Medicine. 2025; 14(5):1774. https://doi.org/10.3390/jcm14051774

Chicago/Turabian Style

Loos, Eva, Suzan Sekar, Christiane Rosin, Alexander A. Navarini, Chrysovalandis Schwale, Rainer Schaefert, and Simon Müller. 2025. "The Relationship Between Chronic Pruritus, Attention-Deficit/Hyperactivity Disorder, and Skin Picking—A Case Series and Narrative Review" Journal of Clinical Medicine 14, no. 5: 1774. https://doi.org/10.3390/jcm14051774

APA Style

Loos, E., Sekar, S., Rosin, C., Navarini, A. A., Schwale, C., Schaefert, R., & Müller, S. (2025). The Relationship Between Chronic Pruritus, Attention-Deficit/Hyperactivity Disorder, and Skin Picking—A Case Series and Narrative Review. Journal of Clinical Medicine, 14(5), 1774. https://doi.org/10.3390/jcm14051774

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