The Interdisciplinary Synergy Between Neurology and Psychiatry: Advancing Brain Health

Abstract

The study of brain disorders has long been central to both neurology and psychiatry, with these two disciplines evolving as distinct yet deeply interconnected fields. In fact, these specialties often share overlapping symptoms, neural pathways, and treatment modalities, making interdisciplinary collaboration essential. Despite this, such collaborations remain sparse, particularly in clinical settings, research, training, and policy development. The increasing global burden of brain disorders has induced a paradigm shift, emphasizing the need for cooperative efforts to preserve brain health. Effective interdisciplinary collaborations between neurology and psychiatry as well as with other partners involved in brain health and other medical specialties is crucial to improving patient outcomes and societal well-being. Furthermore, the development of comprehensive training programs in brain health is vital, aligning with the recent rise in brain medicine as a unified field. This article reviews the historical evolution of neurology and psychiatry, explores current synergies, and identifies areas for future collaboration, particularly in enhancing research, education, and shared preventative strategies. Ultimately, fostering interdisciplinary collaboration between neurology and psychiatry along with other medical specialties and relevant partners will be key to advancing brain health and addressing the global burden of brain disorders.

1. Introduction

The study of brain disorders has a rich history, tracing back to ancient civilizations and evolving over centuries into the distinct yet interconnected fields of neurology and psychiatry. Both fields fundamentally study and address disorders of the brain, often presenting with overlapping symptoms, clinical trajectories, neural circuitry, and relying on shared diagnostic and treatment modalities [1]. Recent advancements in neuroimaging, genetics, immunology, and neuropharmacology have further highlighted the connections between psychiatric and neurological conditions, fostering the development of interdisciplinary collaborations [2]. These collaborations have been proved essential for advancing research and integrating diagnostic, therapeutic, and prognostic methods across both fields but they still tend to remain sparse and with limited application in clinical practice, training, and policy development.

A renewed recognition of the need for synergy between neurology and psychiatry is driven by the pressing need to research, promote, and enhance brain health worldwide. In fact, the rising prevalence and burden of brain disorders, including both neurological and psychiatric conditions [3,4], has led to a paradigm shift, emphasizing the importance of collaborative efforts towards preserving brain health, as well as through advocacy and policy design influence [2,5,6,7,8,9].

The interdisciplinary collaboration between neurology and psychiatry is of paramount importance in the promotion of brain health, as defined by the 2022 position paper from the World Health Organization (WHO), “the state of brain functioning across cognitive, sensory, social-emotional, behavioral and motor domains, allowing a person to realize their full potential over their life course, irrespective of the presence or absence of disorders” [10]. Such promotion will help drive significant improvements in patient outcomes and societal well-being. Furthermore, there is a need for comprehensive training in brain health which has developed in parallel to the emergence of the concept of brain medicine in recent years [9,11,12]. By fostering cross-training between psychiatry and neurology, this approach could help appreciate the breadth and complexity of brain disorders, enhancing the ability to diagnose, treat, and prevent these conditions effectively.

This article explores the historical evolution of neurology and psychiatry, examines current synergies between the two fields and with other partners involved in brain health, and discusses areas for future collaboration to promote brain health, enhance training, and fill the educational gaps in Europe.

2. Historical Perspective

2.1. Origins of Neurology and Psychiatry

The fields of neurology and psychiatry, now often viewed as distinct disciplines, have origins deeply intertwined with the study of the brain and its disorders. While a comprehensive historical overview is beyond the scope of this article, this section explores the historical development of brain disorder studies, the rise and evolution of neurology and psychiatry, and the factors that led to their separation—essential elements for understanding the evolving relationship between these two fields.

2.2. Early Understandings of Brain Disorders

Ancient texts, like the Edwin Smith Papyrus and the works of Hippocrates and Galen, suggested that brain disorders were linked to both physical and psychological factors. Hippocrates, for instance, identified the brain as the seat of emotions and intellect, while Galen connected mental illnesses to disruptions in rational functions [13,14].

2.3. The Emergence of Neurology

Neurology as a distinct medical specialty began to take shape in the 19th century with the development of clinical methods for diagnosing and then treating disorders of the nervous system. Jean-Martin Charcot, a French neurologist, is often regarded as the founder of modern neurology [15]. Trained as a pathologist, he identified the crucial connections between clinical and anatomical findings by correlating clinical observations with autopsy results. At the same time, Charcot was also able to recognize the intertwined nature of the relationship of psychosocial factors on the development of neurological conditions and recognized the role of stress to the development of “dynamic lesions” responsible for “hysterical paralysis” [15].

The same systematic approach, attention to clinico–anatomical associations, and correlations with psychological factors were also fundamental to the work of John Hughlings Jackson and Paul Broca, a British and a French physician, whose contributions laid the foundations of clinical neurophysiology, epilepsy research, neurolinguistics, and the study of cerebral localization of brain functions [16,17].

2.4. The Development of Psychiatry

While neurology focused on organic and structural abnormalities of the nervous system, psychiatry emerged as a field dedicated to the study and treatment of mental illnesses. The late 19th and early 20th centuries saw further developments in psychiatry. Theodor Meynert was an influential scholar of the time, integrating philosophy and evolutionary theory into his work on the cerebral cortex’s structure and its connections with other brain and spinal areas [18]. He developed a holistic theory of brain/mind disorders, laying the groundwork for the later development of neuropsychiatry and influencing the work of psychiatrists like Emil Kraepelin. Kraepelin’s key achievement was linking the pathogenesis and manifestation of mind disorders, differentiating between “dementia praecox” (now known as schizophrenia) as a progressive, biological illness and “manic depression” as an episodic disorder. His distinction between these forms of psychosis has shaped psychiatric understanding for over a century [19] and paved the way for the influential work of Eugen Bleuler, a psychiatrist who later conceptualized “‘fundamental anomalies in connections”’ in schizophrenia, anticipating today’s concepts of functional neural dysconnectivity [20].

Despite the appearance of this initial divide, scholars in both fields regarded themselves as neuropsychiatrists and often held academic positions in both neurology and psychiatry [21].

2.5. Divergence of Neurology and Psychiatry

The divergence between neurology and psychiatry became more pronounced in the early 20th century with neurology increasingly focused on diseases with identifiable pathological changes in the nervous system. The advent of advanced diagnostic tools, including electroencephalography (EEG), CSF analysis, and neuroimaging techniques, further reinforced neurology’s focus on structural, biological, and electrophysiological abnormalities [2,16,17], emphasizing objective clinical observation of brain disorders, often at the expense of considering psychological and subjective factors [2,22].

In contrast, psychiatry centered on the mind and unconscious psychological processes, often sidelining the organic aspects of mental illness. The emergence of Freud’s psychoanalytic theory further highlighted the significance of unconscious processes, childhood experiences, and psychological conflicts in the development of psychiatric illness. This psychoanalytic approach dominated psychiatry for much of the early 20th century, reinforcing its focus on the mind rather than the brain [23].

Although these developments were instrumental for the advancement of neurology and psychiatry, they reinforced the dichotomy between the brain and the mind.

This conceptual distinction further led to the development, from the 20th century onwards, of two distinct clinical specialties initially in Europe and then in North and South America, Asia, Oceania, and finally in Africa [24,25,26,27,28]. In Europe, this separation took place more consistently after the second world war and in several countries, including Austria, France, Germany, Italy, and Switzerland, it was still possible to complete a joint training in neurology and psychiatry until the late 20th century [29].

3. Contemporary Perspectives: Towards Integration

In recent decades, there has been a growing recognition of the need for an integrated approach that bridges both neurological and psychiatric perspectives. In fact, advances in neuroimaging, neurotechnology, genetics, and molecular biology have revealed the complex interplay between brain structure, function, behavior, and psychosocial factors challenging the artificial divide between neurology and psychiatry [30,31].

Increased recognition of shared clinical trajectories between psychiatric and neurological conditions further supports the notion of common underlying pathways [32]. Compelling evidence has also linked psychiatric disorders to neural substrates [33], while helping define the circuit-level mechanisms that underpin pharmacological and psychotherapeutic treatments in psychiatry. Furthermore, cross-fertilization with neurology could positively impact the standardization of diagnosis and treatment of psychiatric conditions through the use of a neurological method of meticulous examination and documentation [1,31]. In addition, this interaction could also help destigmatize psychiatric disorders by highlighting that the brain and mind are ultimately one interconnected entity and fostering greater understanding and parity in the treatment of psychiatric conditions [34].

On the other hand, neurology has increasingly recognized the psychiatric manifestations of conditions once considered purely neurological, emphasizing the need for appropriate care in these cases [1]. Growing evidence suggests that psychosocial factors, premorbid personality traits, and psychiatric comorbidities in neurological conditions are associated with more severe presentations, as well as higher morbidity and mortality. For example, affective disorders and psychotic symptoms are common in Parkinson’s disease, aggravating motor symptoms and complicating treatment [35,36], and post-stroke depression is associated with increased mortality in stroke patients [37]. Also, it was reported that people with epilepsy are significantly more likely to experience psychiatric disorders compared to those without epilepsy [38]. Therefore, there is a stringent need for neurologists to adopt a more holistic approach that incorporates early recognition of psychiatric factors and comprehensive care to their patients [1].

Finally, neurological and psychiatric disorders share common risk factors, ranging from poor nutrition, shared genetic vulnerability, reduced social interaction to inadequate sleep and exposure to air pollution and heavy metals [5,39,40,41]. Therefore, an integrated approach to these conditions is essential for providing optimal care, particularly in the context of preventive medicine, as detailed below.

4. A New Paradigm of Brain Health at the Convergence of Neurology and Psychiatry

Brain health has become a crucial concern in both Switzerland and Europe, as brain disorders, including neurological and psychiatric disorders, place a substantial health and economic burden on societies [42,43,44,45] and require an interdisciplinary and collaborative approach between neurology and psychiatry. Recent reports from the Global Burden of Disease (GBD) Consortium estimate that neurological disorders affected 43.1% of the global population in 2021 [4], while psychiatric disorders impacted 12.5% in 2019 [3]. The increased prevalence of brain disorders is also associated with increased direct and indirect health costs [6,46,47]. In fact, these conditions can lead to varying levels of disability and impairment, affecting cognitive function, mobility, communication and are also responsible for increased mortality [3,4]. They also impose emotional distress, stigma, social isolation, and discrimination on affected individuals, as well as placing a significant burden on caregivers, families, healthcare systems, and economies worldwide.

The 2021 GBD assessment also showed that neurological conditions can be prevented through better awareness, vaccination, and global prevention efforts, with significant reduction in DALYs for conditions like tetanus, meningitis, and stroke [4]. Similarly, early interventions, such as nurturing environments, parenting programs, and social support, have also been effective in preventing mental health disorders and promoting well-being [48,49].

The burden of brain disorders and the need to prevent these conditions and promote brain health have led to a paradigm shift at multiple levels. At the institutional level, advancing brain health demands the creation of platforms that bring together clinical specialist societies, patient organizations, public health experts, institutions, regional health ministries, and industry partners.

In the clinical field, neurologists and psychiatrists are experiencing a Copernican revolution. For years, they have been trained primarily to diagnose and treat diseases, rather than to focus on promoting brain health [50]. This shift means that specialized clinicians will also play a key role in raising awareness about brain health and the burden of brain disorders. They should also understand the impact of environmental and social factors on their patients and collaborate with other specialties that share common risk factors [8]. They also need specific training to communicate risks to healthy populations and engage with policymakers to advocate for brain health. To achieve this, neurology and psychiatry specialty training needs to be restructured and implemented.

This paradigm shift also requires rethinking our models of care and identifying successful novel approaches to integrated care. It requires the development of innovative tools to detect brain disorders at their earliest stages and provide effective treatments with minimal side effects, enabling better management of risk in healthy populations. Additionally, precise metrics of brain health are needed to monitor the impact of these interventions.

In the following sections, we will explore the emerging synergies aimed at addressing these growing challenges across the various levels outlined above, as well as key areas of development.

4.1. Synergies at the Institutional Level

The WHO’s pivotal publication, “Intersectional Global Action Plan on Epilepsy and Other Neurological Disorders”, emphasized that preventing neurological diseases requires a strengthened, interdisciplinary, multi-sectoral and life-long approach, leveraging synergies for optimal outcomes [51]. This approach is also considered equally relevant for the WHO “Mental Health Action Plan (2013–2030)” that stresses the importance of integrating the promotion mental health and the prevention of psychiatric conditions in other priority health programs in order to provide integrated and responsive care and to address brain health more broadly [52].

Moreover, this integrated approach also extends beyond brain health as many risk factors associated with brain disorders also contribute to an increased risk of other common non-communicable diseases [53]. This overlap creates opportunities for broader collaborations beyond the neuropsychiatric sphere, fostering a virtuous cycle that could enhance global health outcomes.

However, despite the relevance of these plans, the adoption of their strategies and progress on the WHO framework objectives remain insufficient, particularly in low- and middle-income countries, where the burden of brain disorders is especially high [54].

At the European level, the multidisciplinary aspect of the promotion of brain health is also acknowledged. In fact, the European commission will launch in 2025 an intersectional European Partnership for Brain Health with the ultimate goal to promote brain health in society and to enhance the well-being of people with neurological and psychiatric conditions in Europe and worldwide [55].

Additionally, in 2022, the European Academy of Neurology defined and launched a comprehensive brain health strategy that aimed to reduce the burden of neurological diseases and to enhance brain health across Europe [50]. While the primary focus was on neurological disorders, the EAN’s approach emphasizes the importance of a unified strategy that integrates various specialties through international collaborations and local initiatives to improve brain health outcomes and support sustainable development goals.

Notably, all EAN efforts to promote brain health are carried out in collaboration with broader consortia [56], including the European Brain Council, a non-profit organization that brings together the European Psychiatric Association, but also patient organizations, other professional societies, and industry partners, with strong ties to European institutions.

This collaboration plays a vital role in shaping European health and research policies, raising awareness and fostering education about the brain and the societal impacts of neurological and psychiatric conditions [57].

In Switzerland, the program that promotes brain health including, from its inception, professionals from different specialties, including neurology and psychiatry, is the Swiss Brain Health Plan (SBHP) [6]. The SBHP recognizes the vital role of cross-disciplinary and interprofessional collaborations to tackle brain disorders and promote brain health and underlines the importance of having a holistic (non-disease-specific) and integrated approach when it comes to the definition of public health measures [6].

The SBHP is developing educational programs on brain health to raise awareness among the general public [6,56]. Public awareness can drive bottom-up initiatives that translate public health needs into effective policy strategies. These initiatives can also stimulate community-based efforts that convert high-level policies into actionable educational programs, tailored to the sociocultural, geographical, and minority characteristics of the national population. Notable examples are the “brain health school challenges” [56] that integrate education on brain health in primary and secondary schools and the “memory cafés” [58] for dementia that provide support to individuals with dementia and their caretakers, promoting access to education, information, and resources. These initiatives play a crucial role in combating misinformation and misconceptions about brain disorders. However, they are still insufficient to meet to the needs of individuals with brain disorders that still report experiencing stigma [7,54].

The SBHP has highlighted the need for interprofessional and interdisciplinary programs to fill the gap in education, in raising awareness on brain health [6,56]. In this context, a Certificate of Advanced Studies (CAS) in Brain Health has been developed at the University of Bern with faculty members from the SBHP. This course aims to provide different healthcare but also public health professionals with the necessary knowledge on brain health determinants, brain disorders, intervention techniques, and strategies to promote brain health, equipping students with the tools to develop individualized sustainable action plans for improving brain health [59].

4.2. Synergies Between Neurology and Psychiatry: Filling the Gap of Training Needs

The promotion of brain health demands a holistic approach that not only focuses on treating existing conditions but also emphasizes prevention and the development of effective public health strategies. This requires a shift in the way we train medical specialists, blending clinical expertise with leadership, advocacy, and public health skills to better serve the needs of patients and of the general population [9].

Regarding interdisciplinary training, despite the separation of neurology and psychiatry into distinct specialties throughout the 20th century [29], both fields recognize the importance of cross-training and the need of professionals capable of working across these boundaries. The European Training Requirements for neurology and psychiatry recommend an optional training period in the other specialty [29,60], and early-career trainees have expressed a desire for dedicated neuropsychiatry training with a clearly defined curriculum at their institutions [61]. Furthermore, in approximately 20 European countries, it is possible to integrate a rotation in the other specialty into the respective training programs in neurology and psychiatry [62,63].

However, these interdisciplinary programs remain limited to less than one year and are generally offered as optional, rather than mandatory, components of training. An analogous situation has been observed in the United States of America (USA), where psychiatry residency program directors reported that, despite the availability of rotations in neurology, these rotations were considered suboptimal in terms of their organization and significance in training. This has led to calls for more comprehensive exposure to patients with neurological conditions, particularly in the outpatient setting [64]. In the USA, one of the primary barriers to integrating neurology and neuroscience into psychiatric training has been the limited availability of qualified faculty members and curricula that adequately address these areas of expertise [65].

To address similar issues and needs, the United Kingdom (UK) offers specialized programs dedicated solely to neuropsychiatry [66]. This field addresses conditions that straddle the boundary between neurology and psychiatry, such as traumatic brain injury, neurodegenerative diseases, and epilepsy with comorbid mood disorders [67,68,69]. In Australia and the USA, a specialized curriculum for neuropsychiatry was developed to meet the growing demand for training at the intersection of neurology and psychiatry [70,71,72]. Early evidence suggests that neuropsychiatry-focused interdisciplinary training has been successful, with small cohort studies showing high satisfaction, improved knowledge retention, and better performance in interdisciplinary fields among residents who have undergone this training [73,74].

Despite the development of these programs and curricula, the definition and scope of neuropsychiatry vary significantly across different countries and training programs in neuropsychiatry are limited in number and often inconsistently labeled, reflecting the lack of standardized education and certification across borders [61]. Moreover, there is a lack of large, well-designed studies that evaluate the clinical and educational outcomes of combined or mixed training periods. This makes it difficult to assess the long-term benefits of such approaches and whether they could be scaled up effectively.

Another emerging idea is the establishment of a “brain medicine” specialty, which would combine aspects of both neurology and psychiatry [11,12]. Such training programs would resemble those in internal medicine, where interns first acquire a broad foundation in internal medicine before refining their skills in specific subspecialties. Similarly, brain medicine programs would establish a shared foundation across both specialties, allowing trainees to develop specific interests and skills over time. This approach would evolve beyond the current dualism, integrating cross-disciplinary knowledge into practice. Such holistic care may benefit individual patients and could also optimize healthcare expenditures by promoting brain health and reducing disease recurrence. However, there are significant challenges in implementing such a model. First, the demands of education and clinical training for a combined specialty would be timeconsuming and potentially difficult to accommodate within existing structures. Furthermore, any such overhaul would require a fundamental change in the educational system, which could be met with resistance.

Also, the traditional focus on clinical skills alone is insufficient to meet the demands of modern brain healthcare, particularly when it comes to prevention and awareness. Indeed, the concept of brain health underscores another critical need: neurologists and psychiatrists must expand their skillsets beyond clinical expertise to include advocacy, leadership, and knowledge of global and public health. However, these areas are not sufficiently covered in European postgraduate training programs [75,76,77,78], despite their importance in tackling the growing burden of brain disorders and promoting brain health at both the public and policy levels.

There is no one-size-fits-all solution to address the educational needs of future specialists in this field, as each model comes with its own set of advantages and challenges. However, there is an obvious lack of comprehensive studies evaluating the effectiveness of current training systems or pilot programs for new models. This gap highlights the urgent need for further research and development. Identifying and testing more effective models could enable the implementation of existing interdisciplinary training programs or the creation of new ones if current systems do not yield positive educational and clinical outcomes. Such advancements would ensure that future professionals are better equipped to recognize and address brain health issues that span both neurology and psychiatry, ultimately providing improved care for patients [34].

4.3. Integration in the Diagnosis and Management of Brain Disorders

Due to the substantial overlaps in clinical presentation and the necessity for integrated management of patients with complex brain disorders, there has been growing interest in developing shared and innovative approaches to brain healthcare [79]. These models advocate for patients’ access to holistic care that involves the collaboration of psychiatrists and neurologists in an integrated fashion. These approaches have the potential to allow timely diagnosis of brain disorders, real-time integrated practical recommendations, follow-up with optimal healthcare service utilization and navigation for patients with complex brain disorders. Despite these advantages at the individual level and the potential benefits for the healthcare system costs, these collaborative models are still sparsely present. A report on neuropsychiatric services in London revealed that care in this field was limited, predominantly provided by academic centers, and hindered by fragmented strategic planning, inadequate funding, and the complexity of navigating multiple funding streams [80]. This situation likely mirrors that of other European countries, highlighting a growing need to advocate for the development of integrated healthcare policies at both institutional and governmental levels. Such policies are instrumental in supporting the advancement of multidisciplinary care models.

4.4. Clinical Synergy for Brain Health: An Example of Interdisciplinary Collaboration in Dementia Prevention

The field of dementia prevention represents a notable example of how interdisciplinary collaboration can lead to a successful outcome, such as identifying risk factors, planning targeted actions, and developing new models of integrated care to meet the evolving needs of diverse populations, including healthy individuals seeking to prevent brain disorders.

The first notable collaboration in this field was the Lancet Commission on Dementia Prevention, Intervention, and Care, established in 2017 [81]. Comprising neurologists, psychiatrists, neuropsychiatrists, geriatricians, and epidemiologists, the commission was formed to consolidate emerging evidence on dementia prevention and to propose actionable preventive strategies. This commission produced reports in 2017, 2020, and 2024, with the latest showing that the modification of 14 risk factors including depression, cardiovascular risk factors, hearing loss, and socioenvironmental factors can prevent or delay nearly half of dementia cases [81,82,83]. They provided concrete multidimensional actions to reduce dementia risk across the life course. While emphasizing the importance of individually tailored measures, they have also underscored the fundamental role of advocacy in driving changes in policies at the national and international governmental level.

At the European level, an international and interdisciplinary task force led by the University of Geneva, and composed of scientists from twenty-eight institutions, introduced in 2023 the concept of brain health services [84], new models of care that will respond to the needs of a population of cognitively unimpaired individuals for whom clinical pathways have not yet been integrated in general practice and in memory clinics. The brain health service will provide answers to this population about dementia risk profiling and risk communication. Also, these services will foster multidomain precision interventions to reduce dementia risk and consider protocols for cognitive enhancement. This task force also defined a user manual to build up these services, to overcome potential challenges and to consider societal and equity challenges that could help in building an international network of brain health services [85,86,87,88,89,90].

4.5. Synergies Through Research: Measuring Brain Health

Given the complexity and multifaceted nature of brain health, defining and capturing all its aspects is challenging, and quantifying it with a single metric is currently unattainable. No comprehensive test or evaluation exists that encompasses all dimensions of brain health, including psychiatric and neurological disorder prevention, and related social factors. A universally acceptable, multidimensional, and sensitive tool for assessing brain health is crucial for developing effective preventive programs. However, the absence of such a metric is due to both the complexity of brain health and the incomplete understanding of risk and protective factors for various brain disorders, as their pathogenesis still remains partly unclear [91,92].

To address this, it is essential to advance multidisciplinary and longitudinal studies that identify risk and protective factors for brain disorders and clarify their pathophysiological mechanisms. Such research will support the development of evidence-based interventions that transcend disease categories, offering a continuum of care tailored to individual needs. This approach should also respect cultural, ethnic, and geographical differences in brain health and disease, from primary to secondary prevention.

However, making progress in this field will require dedicated funding, as current European investments in brain disorder research are insufficient to tackle the growing healthcare burden posed by these conditions [56].

4.6. Synergies in Brain Activity Modulation: The Role of Non-Invasive Brain Stimulation

In the evolving field of translational neuroscience, non-invasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES), either with direct or alternate electrical currents (tDCS and tACS), are emerging as powerful tools to modulate brain activity in both neurological and psychiatric conditions. These methods have shown promise in both improving cognitive functions and providing therapeutic benefits, with relatively few side effects [93].

Recent studies have demonstrated that NIBS can serve diagnostic and therapeutic roles in both fields. In neurology, TMS-based biomarkers have proven effective in discriminating different forms of neurodegenerative diseases both at the stage of dementia and mild cognitive impairment and to predict the rate cognitive decline [94,95,96]. These biomarkers are also effective to reliably identify patients with Alzheimer’s disease (AD) from healthy controls [97] and they improved the diagnostic accuracy when employed with plasma biomarkers [98]. Furthermore, both TMS and tES techniques have shown potential for cognitive rehabilitation, particularly in dementia, where protocols targeting brain regions like the dorsolateral prefrontal cortex (dlPFC), precuneus, and temporal lobe have improved cognition and slowed cognitive decline [99,100,101,102,103]. For psychiatric disorders, TMS has been approved for treatment-resistant depression and obsessive–compulsive disorder (in the USA, Australia, and The Netherlands) [104], with promising results, especially with accelerated protocols targeting the dlPFC in depression [105] or to reduce negative symptoms in schizophrenia [106].

These techniques highlight the transdiagnostic overlap in symptoms and circuits between psychiatric and neurological conditions. Both fields benefit from insights into brain network connectivity, as interventions like rTMS and tES influence cognitive processes that span disorders in both specialties.

Moreover, NIBS does not only benefit individuals with cognitive decline and neuropsychiatric disorders, but also demonstrates improving episodic memory and working memory in healthy individuals through the use of tACS protocols, opening new potential perspectives in primary prevention of brain disorders in people at risk of cognitive decline [107,108].

However, challenges remain, including the need for more reliable biomarkers, better standardization of stimulation protocols, and deeper understanding of interindividual variability in treatment response. From its proof-of-concept in 2017, transcranial temporal interference stimulation (tTIS) has emerged as a promising technique, offering high focality and the potential for individualized, circuit-based treatments [109,110,111,112]. By overcoming the limitations of conventional NIBS methods, tTIS could revolutionize treatment, offering tailored interventions for both neurological and psychiatric conditions, potentially bridging the gap between these two fields.

Ultimately, integrating these approaches into a transdiagnostic model could provide more personalized and effective treatments for a range of neuropsychiatric disorders, fostering greater collaboration between neurology and psychiatry to enhance brain health.

5. Conclusions and Future Directions

The evolution of neurology and psychiatry has underscored the intricate and interconnected nature of brain disorders. Historically distinct, these fields have increasingly demonstrated their overlap through advancements in neuroimaging, genetics, and neuropharmacology. The cross-fertilization of neurology and psychiatry and their interactions with other medical specialties is not only beneficial to each of the disciplines, but essential in advancing both research and clinical practice to face the challenges of the 21st century. Despite considerable progress, the practical application of interdisciplinary approaches remains limited, highlighting the need for more cohesive strategies in training, clinical practice, and policy development.

The rising prevalence and burden of brain disorders have emphasized the importance of promoting brain health through collaborative interdisciplinary efforts. The increasing recognition of brain health as a multidimensional concept, as outlined by recent WHO definitions, reinforces the necessity for a unified approach that transcends traditional disciplinary boundaries. This approach can lead to improved patient outcomes and more effective utilization of healthcare resources.

The emergence of neuropsychiatry and the drive for comprehensive brain health training reflect a growing understanding that a holistic approach to brain health is crucial. By integrating knowledge across disciplines, future healthcare professionals can better address the complexity of brain disorders and improve diagnostic and therapeutic practices. However, there is a lack of research assessing the most effective programs, structures, and strategies for achieving this integration. Addressing this research gap is crucial for identifying programs that yield optimal educational and clinical outcomes and are scalable at a European level. Furthermore, achieving true integration requires overcoming institutional and cultural barriers, fostering collaboration, and addressing the challenges inherent in current training models. Additionally, new training needs are emerging alongside the concept of brain health, particularly the need to expand the skill sets of neurologists and psychiatrists beyond their traditional specialties. This includes training in global and public health, advocacy, leadership, and communication. Equipping specialists with these skills will empower them to advocate for brain health promotion at institutional levels and engage the general public through awareness initiatives and effective leadership.

Successful examples of interdisciplinary collaboration, such as the Lancet Commission on Dementia Prevention [81], demonstrate the potential for significant advancements when multiple specialties work together. These collaborations have led to actionable strategies for dementia prevention and exemplify how shared knowledge can enhance patient care and inform policy.

The complexity of brain health necessitates the development of comprehensive, multidimensional assessment tools that capture its full scope. While no single metric currently exists, ongoing research and the advancement of multidisciplinary studies are crucial for identifying risk and protective factors, elucidating pathophysiological mechanisms, and tailoring interventions to individual needs. This research should also consider cultural, ethnic, and geographical differences to ensure that brain health strategies are globally relevant and effective. Increased investment and collaborative efforts are critical to making this research financially sustainable and impactful.

In conclusion, the integration of neurology and psychiatry, along with collaboration from other partners involved in brain health promotion, is pivotal for advancing brain health and addressing the global burden of brain disorders. By fostering interdisciplinary collaboration, enhancing training, and supporting research, we can develop more effective prevention, diagnosis, and treatment strategies. This holistic approach will not only benefit individuals but also contribute to more sustainable and equitable healthcare systems worldwide.