Introduction

Dementia is a major public health challenge as it affects around 45 million people worldwide (1). It is one of the major causes of disability and dependency among older people (2). Impairments of memory and cognitive functions are the most characteristic signs of this pathology. However, balance and walking disorders are frequently observed (3), worsening the patient’s global condition and indicating a poor prognosis. Thus, the quality of life of the patient and his/her family is severely affected (4).

Alzheimer’s disease is the most common cause of dementia, causing between 50 and 75% of cases. The pharmacological treatments currently available aim at treating the symptoms, but current data show that they are only moderately effective in the best of cases (1). Faced with this observation and given the numerous mechanisms involved, many teams experiment with a reorientation of the interventions in favor of functional, psychological, and psychosocial approaches (5). These new approaches aim at optimizing the patient’s well-being and quality of life as well as delay, prevent or reduce adverse outcomes of the disease.

Music and dancing are thought to induce numerous benefits on the motor function (6). Dancing involves rhythmic movements of the limbs and trunk and music provides external cues that facilitate movement (7). Music and dancing have been shown to encourage patients to develop attention, memory, rhythm, coordination, balance, and self-perception of the body in space (8). Therefore, music and dancing are commonly used as complementary therapies in various pathologies such as cardiovascular diseases (9), Parkinson’s disease (10), or cancer (11).

Previous literature reviews have examined the health benefits of dance (12-18). However, there is to our knowledge no study that reviewed quantitative studies investigating the effects of dance on the functional abilities of older people with dementia. In 2017, Karkou and Meekums (14) published a systematic review about the effects of dance movement therapy (DMT) on people with dementia. The review was focused on psychosocial outcomes and age was not an exclusion/inclusion criterion.

Mabire et al. (17) included studies implementing a dance intervention for people with dementia. However, the authors did not integrate inclusion/exclusion criteria about age, types of outcomes, nor study designs. The systematic review of Ruiz-Muelle and López-Rodriguez (13) had no restrictions on the age or cognitive status of the participants.

Our systematic review focused on quantitative trials using therapy-based dance interventions in people with dementia over the age of 65. This review aimed to analyze the effects of dance therapy on physical skills in older adults with dementia.

Materials and Methods

This systematic review was based upon the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines (19).

Search Strategy

Up to March 2020, an electronic search was conducted to identify relevant studies published in the following databases: PubMed, Web of Science, Scopus, and ALOIS. The search terms were «dementia», «alzheimer», «dance», «dancing», «older adults» and «elderly». bibliographic references of the included articles were examined to search for articles that had escaped the initial search strategy.

Eligibility Criteria

Our review included experimental studies, available in full text, and published in English, French, Portuguese, or Spanish. Excerpts from congresses, case reports, protocols, books, essays, and thesis were excluded.

We considered studies including individuals who met the following criteria: Individuals aged 65 or above; diagnosed with dementia; trials that were limited to participants with mild cognitive impairment, or with a mini mental state examination (20) score over 24 were excluded; studies about Parkinson’s disease were excluded.

Experimental interventions aiming at finding some benefit of scheduled dance sessions were included. The sessions included movements to the rhythm of music with the presence of an instructor, therapist, or guide. We included studies reporting quantitative results regarding gait quality, gait speed, endurance, balance, strength, and the ability to carry out the activities of daily living (ADL).

Study Selection

The references of articles resulting from the research were exported to Mendeley©. We then carried out an automatic reference check to target and eliminate duplicates. Two reviewers (LB and GP) carried out an examination of article titles and abstracts for eligibility. Subsequently, the full texts of potential studies were screened to determine final eligibility for inclusion. Disagreements about the eligibility were resolved by discussion and consensus between the reviewers.

Data Extraction

One reviewer (LB) extracted the following data from the studies: Design, objective, sample characteristics, description of the intervention of the experimental and control groups, and outcome measures. These data were compiled in Table 1.

Study Quality Assessment

Two reviewers (LB and GP) independently assessed the methodological quality of each included article, using a standardized checklist of 12 predefined criteria developed following de Vet et al. (21) recommendation for the quality assessment of trials in physical therapy. The 12 criteria are: (1) comparison with a control group; (2) randomization; (3) blinding participants; (4) homogeneity of groups at baseline; (5) alternative activity for the control group; (6) intentions (7); inclusion/exclusion criteria; (8) at least two socio-demographic variables (9); comorbidity (10); intervention description (11); dropouts; (12) valid outcomes measures. If the criteria were met, a point was assigned. If the criteria were not met or were not sufficiently described, no point was assigned (Table 2).

Studies that met more than 75% of the criteria were classified as high quality. Studies that met between 50 and 75% of the criteria were considered as moderate quality. Studies that met less than 50% of the criteria were classified as low quality.

Results

A flow diagram of the study selection process is shown in Figure 1. A total of six studies were included in this systematic review. The most important excluded studies with reasons for exclusion are shown in Table 3.

Characteristics of Included Studies

Included studies were published from 2008 to 2019 and conducted in France, Brazil, Spain, Finland, Singapore, and Australia. Two were randomized controlled trials (RCT), (22,23) one was a pilot RCT, (24) one was a controlled clinical trial (25) and two used a quasi-experimental design (26,27).

A total of 208 participants were involved in this review. Among them, 135 persons were assigned to intervention groups. The mean age of participants ranged between 76 and 82 years. Mean MMSE scores were between 12 and 23.5. Participants of most studies (22-25,27) came from nursing homes and care homes. Only Koh et al. (26) included community-dwelling participants, but the participants were recruited from a day-care center for persons with dementia.

The dance style was found to vary between studies. Brami et al. (25) used a virtual dance intervention. During the program, choreographies followed an increasing level of difficulty concerning the rhythm, intensity, and complexity of the movements. Borges et al. (23) proposed a ballroom dance program with various musical rhythms (foxtrot, waltz, rumba, swing, samba, and bolero). Gomez Gallego and Gomez Garcia (27) used musical therapy sessions with songs that were appreciated by the participants. Sessions included: A welcome song, rhythmic accompaniment activities with clapping and musical instruments, movements with background music, dance therapy with rings and balls, and a farewell song. The interventions of Hokkanen et al. (22) consisted of DMT sessions.

Koh et al. (26) used a person-centered creative dance intervention, which comprised simple warm-up physical exercises, improvised movement based on culturally appropriate music familiar to the generation of the participants, collaborative exercises that required arm movement coordination, and social occasions for greeting and sharing with the therapist and other participants. Low et al. (24) used a program led by a professional dancer. Popular music from the 40s, 50s, and 60s, and a mixture of dance types (ballroom, tango, folk dance) were incorporated.

Main Functional Outcomes

Three studies assessed balance (23-25) and one assessed balance confidence. Borges et al. (23) found significant improvements using stabilometric and postural platform assessments. Brami et al. (25) and Low et al. (24) assessed the balance component in the short physical performance battery (SPPB). Low et al. (24) did not report the results for each subtest. However, the mean SPPB score was reported to decrease from 6.8±1.6 to 5.9±1.8 after 16 weeks of intervention. Brami et al. (25) found no significant differences in balance after the intervention. Otherwise Koh et al. (26) found a non-significant improvement in balance confidence, evaluated using the CONFbal scale.

Gait speed was measured in four studies (23-26). Borges et al. (23) found a significant intragroup improvement in the 10-metre gait speed (pre-test: 21.67±6.22 s, post-test 16.05±4.06 s, p<0.05) and a significant intergroup difference in the post-test (CG: 22.06±5.16 s, p<0.05). Brami et al. (25) found significant intergroup differences in the 4-metre gait speed post-test (CG: 8.27±1.24 s, IG: 5.96±1.46 s, p=0.02) but non-significant intragroup improvement (pre-test: 6.69±1.68 s, p=0.25; post-test: 5.96±1.46 s). Koh et al. (26) used a 6-metre gait speed and found a non-significant improvement (pre-test: 0.72±0.20 m/s, post-test: 0.76±0.22 m/s, p=0.114).

Gomez Gallego and Gomez Garcia (27) and Koh et al. (26) assessed performances in ADL with respectively the Barthel index and the functional independence measure. Both studies reported no significant improvement. Hokkanen et al. (22) used the nurses’ observation scale for geriatric patients (NOSGER) to assess behavioral aspects of mental functioning in daily life. Control and intervention groups did not differ according to the total NOSGER score. However, the control group deteriorated on the self-care subscale compared to baseline. Borges et al. (23) also measured performance in two daily life activities: The time to stand up from a ventral decubitus position and the time to put on and take off a t-shirt. The authors found a significant improvement after the intervention for both performances.

Quality Assessment

The overall quality of included studies was moderate. The mean quality score was 6.5, with a range of 6 to 8. No trial blinded neither participants nor professionals. Only one study [Low et al. (24)] had a control group engaged in another activity (music appreciation and socialization groups also led by the dance teacher). Only one trial (27) reported comorbid conditions in participants.

Discussion

This systematic review aimed to analyze the effects of dance therapy on functional outcomes in older adults with dementia. According to the trials examined, dance-based interventions may lead to improved physical abilities in older people with dementia. Only Borges et al. (23) found a significant improvement in balance and lower limb strength. Walking speed and timed up and go performance significantly improved in two studies (23,25). ADL performance significantly improved in Borges et al. (23). Additionally, Hokkanen et al. (22) reported a significant intergroup difference after the intervention.

Nonetheless, the evidence of a positive impact of dance on the physical abilities of older adults with dementia seems insubstantial. The literature we reviewed failed to provide convincing evidence for several reasons. First, the small number of studies and participants included. In this sense, it is worth recognizing the difficulty of conducting studies of this type. Most of these people are under legal protection measures and it is not easy to obtain agreement from persons in charge for their participation in investigations. Furthermore, older adults with dementia often experience complex psycho-emotional states, (e.g., apathy or mood swing), which may result in low participation in the proposed activities. One can note that heterogeneity is a characteristic of this population. It is therefore difficult to develop a specific activity for a group of people with different abilities. These constraints possibly result in small samples in all the studies we reviewed. Only Borges et al. (23) recruited more than 50 participants.

Otherwise, the quality of the included studies was moderate. Only four trials had a control group, of which only three were randomized; no study blinded the participants and/or the therapist; only two trials provide data about the homogeneity of the groups at baseline and Brami et al. (25) showed an important baseline imbalance in the physical abilities. Only Low et al. (24) proposed an alternative activity to the control group, resulting in an improvement in the internal validity of the trial (28). In contrast, Hokkanen et al. (22) make no mention of the inclusion/exclusion criteria, although it was the only study to report the type of dementia of the participants. Borges et al. (23) make no mention of dementia in the inclusion/exclusion criteria.

The studies analyzed presented the results of small, heterogeneous samples, with different inclusion/exclusion criteria, different intervention kinds, and diverse tools of measurement. This diversity made it difficult to draw conclusions regarding the effect of dance therapy on these people.

Many unanswered questions remain, including the ideal intensity and frequency, appropriate dance styles, and comparisons with an alternative activity. Future studies should have clearer inclusion and exclusion criteria, be based on large samples, propose an alternative activity to the control group, and use validated instruments to produce reliable, comparable results. Furthermore, these studies should present information such as participants’ comorbidities to measure their impact on the results.

In our review, four fundamental factors led us to exclude articles. First, many papers referred to interventions about people with cognitive impairment (29-34) but few articles included people diagnosed with dementia. Many articles were unclear regarding participant inclusion and exclusion criteria, which made the eligibility stage difficult. The review by Ruiz-Muelle and López-Rodríguez (13) about dance for people with Alzheimer’s disease included articles that we excluded because we found no reference to Alzheimer’s disease or other dementias. For example, one of the inclusion criteria for Marquez et al. (35) was an adequate cognitive status, while Lazarou et al. (32) included people with mild cognitive impairment but not dementia. Although they were unclear in their inclusion criteria, the mean MMSE score of the intervention group was 27.6±2.19, showing that they were not people with dementia.

Moreover, we were tempted to include certain articles that did not speak of dementia, but which reported neuropsychological tests that revealed significant cognitive problems among participants. This was the case of the study by Hackney et al. (36) which excluded people with a history of neurodegenerative disease. However, the mean montreal cognitive assessment score was 22.5±4 in the intervention group, showing a certain degree of cognitive problems, and even dementia, among the participants (37).

We included all the studies that used dance as the main intervention instrument. We did not consider some studies, because they used dancing in a small part of the intervention and not as the main tool (38-40).

Many of the analyzed studies were conducted using a qualitative design (41-44). We decided to restrict ourselves to trials using a quantitative design because we considered it difficult to objectify and analyze changes in physical function in a qualitative way. Furthermore, in general, qualitative studies aim to observe psychosocial and behavioral aspects and exclude the results of physical function.

Interventions performed on people with dementia primarily seek psychosocial, behavioral, emotional, and neurocognitive benefits (45-50). The motor component, fundamental for independence in ADL, is less frequently considered. However, there is evidence of the relationship between the ability to carry out ADL and depression (51), agitation (52), etc.

Agreements and Disagreements with Other Studies or Reviews

The conclusions drawn from this review partially agree with the conclusions of the included studies. Dance seems to be an intervention appreciated by older people (41) and could bring great benefits. According to Hwang and Braun (12), strong evidence suggests that dance, regardless of style and intensity, significantly improves older adults’ functional fitness. However, we cannot be sure that this statement also applies to older persons with dementia. Gomez Gallego and Gomez Garcia (27) and Koh et al. (26) pointed out the need to expand the sample and add a control group to measure the placebo effect.

No trial met the inclusion criteria of the review by Karkou and Meekums (14). The lack of clarity in the selection of participants was one of the reasons. In our review, two of the six articles included did not detail the inclusion and exclusion criteria. This lack of information was recurrent and made it difficult to analyze the results. We agree with Mabire et al. (17) in that detailed information about the dance intervention was incomplete and unclear in some studies. Future research should focus on examining the effectiveness and efficiency of these interventions, by comparing the cost-benefit with that of other interventions.

Conclusion

Even though dance interventions targeting older people with dementia are appreciated and enjoyed, the scientific evidence regarding their benefits on physical abilities is moderate to poor. Although some studies showed an improvement in balance, walking speed, and the ability to carry out ADL, the results of the different studies are heterogeneous and did not allow us to establish an intervention model, with a determined intensity, frequency, and duration, that could be more effective than others. Most existing trials have not compared dance interventions with alternative activities. Therefore, it is unknown whether dance therapy interventions are more effective than other types of non-drug interventions.

Future trials should explicitly set out the criteria for inclusion/exclusion of participants, setting limits through validated measurements. To evaluate the efficacy of dance therapy, RCT with large samples are required, with alternative activities proposed to the control group. It is also essential to implement validated instruments in the search for relevant results. Besides, it is important to detail the methodology of the interventions, stating the resources necessary for their implementation.

Ethics

Peer-review: Externally peer-reviewed.

Authorship Contributions

Concept: L.B., A.P.C., F.M., Design: L.B., G.P., A.P.C., F.M., Data Collection or Processing: L.B., G.P., Analysis or Interpretation: L.B., G.P., A.P.C., F.M., Literature Search: L.B., G.P., Writing: L.B., G.P., A.P.C., F.M.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: This study was been funded in the context of a PhD program by ISATIS Association. This collaboration between Inserm U1093 Cognition, Action and Sensorimotor Plasticity Laboratory. Université dé Bourgogne, and ISATIS Association is framed in a convention of financial contribution for the realization of a doctoral thesis.