**1. Introduction**

Dementia is one of the most common syndromes in old age with an evolution that follows an exponential pattern; it is estimated that by 2030 there will be 82 million people in the world diagnosed with dementia [1].

Alzheimer's disease (AD) is a neurodegenerative disease of unknown etiology characterized by a progressive deterioration of memory and cognitive function and represents between 60 and 80% of dementia cases [2]. In the initial phase, it appears as temporospatial disorientation and a tendency for frequent forgetfulness, in the intermediate phase, the disorientation and memory alterations intensify and provoke difficulties in communication and the need for help to carry out daily life activities. The third phase is characterized by obstacles in orientation, walking, communicating, or recognizing close family members.

Corregidor-Sánchez, A.-I.; Fernández-Moreno, V.; Alcántara-Porcuna, V.; Criado-Álvarez, J.-J. Effect of Doll Therapy in Behavioral and Psychological Symptoms of Dementia: A Systematic Review. *Healthcare* **2022**, *10*, 421. https:// doi.org/10.3390/healthcare10030421

**Citation:** Martín-García, A.;

Academic Editors: Manoj Sharma and Kavita Batra

Received: 15 January 2022 Accepted: 16 February 2022 Published: 23 February 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

The course of AD may be affected by the appearance of psychological and cognitive symptoms of dementia (SPCD) as well. In 90% of AD cases, symptoms such as agitation, psychosis, apathy, sleep disorders, appetite changes, euphoria, irritability, aberrant motor behavior, depression, and anxiety usually appear [3]. Aggression, agitation, delirium, and erratic wandering have been identified as one of the main reasons for the overload of informal caregivers [4,5]. The impact of BPSD is so intense and overwhelming that it provokes high exhaustion, stress, anxiety, and depression in the patient, as well as in the family and caregivers, triggering institutionalization in most cases. Among professional caretakers, several studies have found that SCPD, such as agitation, erratic wandering, and aggressive episodes, may cause negative feelings and discomfort [6], causing a painful experience [7,8] and reducing their work motivation [9].

The development of programs of non-pharmacological interventions such as reminiscence therapy, music therapy, therapy with animals, or sensory stimulation therapy seems to improve the emotional wellness of people with advanced dementia. The common denominator of these techniques is based on achieving positive emotions through pleasant memories, music, or contact with pets that minimize states of anxiety or anguish, diminishing the risk of BPSD.

Doll therapy (DT) is a non-pharmacological technique with the aim to promote attachment, company, and usefulness in people with dementia to increase their wellness and minimize the appearance of challenging behaviors [10,11]. It is based on the combination of three theories: the Attachment Theory, the Transitional Object Theory, and the Person-centered Theory. The attachment theory [12] postulates the need for a human being to establish affective bonds when facing unknown situations, fear, or danger. In this way, people with dementia usually have behaviors related to attachment and fixing phenomena with their parents, looking constantly for them. DT offers the possibility to establish the affective bond needed in stress situations, thus lowering agitation.

The Transitional Object Theory [13] is based on the calming properties that certain objects may have to alleviate and diminish the anguish. Two kinds of objects have been defined: transition objects (known by the subject) [13] and precursor objects (unknown by the subject) [14]. In the case of people with dementia, the doll might be a precursor object introduced in their environment by the caregiver to give comfort and alleviate and diminish the anguish generated by the SCPD [15,16].

The Person-centered Theory was developed by Carl Rogers in 1961 [17] and places the individual at the center of care, being supported and trained to be able to collaborate with the decision-making process. Uniting this approach to positive personal workouts developed by Kitwood [18], DT can offer the possibility of developing game interactions, facilitation, and validation, converting the interactions with the doll into a positive activity and a way to connect with others.

The dolls are designed to recreate the feeling of touching, staring, dressing up, and holding a baby in their arms and can bring to the present-day older roles related to maternity and generate feelings of utility and meaning which may substitute challenging behaviors with care behaviors towards the doll. In this way, the use of dolls with a baby-like appearance (newborn dolls, reborn, or empathy dolls) generated a higher commitment from the patients in comparison with the use of stuffed and other kinds of dolls [19]. Several authors have found benefits in the use of DT, observing a decrease of negative behaviors such as agitation, aggressiveness, or erratic wandering as well as an increase in communication with the environment and independence in daily life [10,11,20]. Systematic revisions in this regard conclude that DT has positive effects on the person with dementia as long as it improves communication with the environment, alleviates the SCPD, and improves quality of life [21–23]. Mitchell [24,25] discovered an increase in commitment levels, communication, and reduction of anguish episodes in addition to the potential of DT to improve independence in daily life. Ng [22] concluded that people with dementia could interact in a better way with their environment after obtaining benefits from the DT. Despite these positive findings on the effect of DT, the authors warn about the scarcity of

empirical studies and the need for a future investigation that includes methodologically correct clinical trials. The objective of this systematic review is double. First, the best evidence available about DT will be examined, including only clinical trials that meet most of the CONSORT (Consolidated Standards of Reporting Trials) criteria. Secondly, the relevant information for the design of treatment protocols and investigation will be extracted to allow for the establishment of clear parameters and facilitating the design of future studies of DT.
