Evidence from a systematic review
Dementia is a public health problem that affects approximately 50 million people worldwide. With the increase in life expectancy, it is estimated that the prevalence of dementia will increase significantly in the coming decades and may triple by 2050.1 - 3 There are several causes of dementia, and its diagnosis depends on the knowledge of the different clinical manifestations and on a sequence of specific complementary exams. The four most common forms of dementia are Alzheimer’s disease (AD), vascular dementia (VD), frontotemporal dementia (FTD), and dementia with Lewy bodies.4 For dementia diagnosis, cognitive or behavioural impairments should affect at least two of the following domains: memory, executive functions, visual-spatial skills, language and personality disorders, or behaviour with symptoms such as mood swings, agitation, apathy, disinterest, and social isolation.3 , 5
Dementia usually occurs in people over 65 years of age. Age-related physical health problems such as diabetes and hypertension increase the risk of AD and VD. Cognitive reserve can be a protective factor for dementia while minimizing cognitive and functional decline. Factors that increase cognitive reserve such as physical exercise, intellectual stimulation, or lifelong leisure activities are associated with a reduced risk of dementia even in individuals with a genetic predisposition.2 , 6
National policies highlight the importance of early diagnosis, treatment, and social inclusion to maintaining a good quality of life for people with dementia.7 Population studies and international epidemiologic consortia have been investigating the clinical diagnosis of dementia and, dementia of the Alzheimer type has well-established diagnostic criteria for epidemiologic research.8 First-line treatment options often involve drugs to slow the progression of the disease and antipsychotic medications to treat behavioural disorders.1 , 2 Individual strategies in choosing the appropriate dementia medication are highly recommended due to the individual course of the disease and different response to the drugs and their adverse effects.8 Music therapy is a non-pharmacological treatment that seeks to minimize symptoms.9 Musical interventions are also used by numerous health professionals in patients with AD.10 , 11
Media interest in this treatment approach has contributed to the public perception that musical abilities represent an “island of preservation” in cognitively impaired people with AD. This intervention can be considered less harmful than pharmacological treatments to improve cognitive functions, mood, and quality of life of these patients.12 When music is used acting as therapy, music performs the primary role in the intervention while the therapist is secondary; when music is used in therapy, the therapist takes the primary role and music is secondary.13 A music therapist is a qualified professional with the capacity to develop musical interventions adapted to the patient’s experiences and illness. Neuromusical therapy, is a clinical intervention modality of music therapy that acts to promote cognitive rehabilitation of neurological patients.14 , 15
Studies with musical intervention have demonstrated the efficacy of treatment for the behavioural and psychological symptoms of dementia, such as agitation, irritability, depression, and apathy.16 - 25 Other studies have investigated the role of music in cognition. In addition, music practice compensates for age-related declines in processing speed, memory, and cognition.11 , 26 , 27 However, there is a lack of randomized clinical trials in the area, and in a recent Cochrane meta-analysis25 on musical interventions in people with dementia, six articles were found with a total of 257 participants, and there was little effect of treatment on general cognition.
In AD, the ability to recognize music remains relatively preserved,28 and patients’ musical memory can be spared, particularly at the onset of the disease.29 The human memory system involves a process of coding, storing, and retrieving information.30 Musical memory can be defined as the neural coding of musical experiences,31 the storage of these experiences, and the subsequent recall of this information. A study by Jacobsen et al. (2015)31 involving AD and music indicated a greater preservation of brain areas involved in the processing of music. The authors found that musical memory seems to be partially independent of other memory systems, and in AD, musical memory may be partially preserved. Neural mechanisms and substrates of musical memory involve different anatomical brain networks. Different aspects of musical memory may remain intact while brain anatomy and cognitive functions are impaired.31 In addition, regions related to musical memory such as the caudal anterior cingulate cortex and the supplemental motor area showed a minimal level of cortical atrophy and disruption of glucose metabolism compared to the rest of the brain. Therefore, β-amyloid deposition in these regions is at an early stage in the expected course of the development of biomarkers for AD and is relatively well preserved. These results may explain the surprising preservation of musical memory in AD.
Recognizing that musical coding may serve as a mnemonic aid in AD, it is important to review the results of studies that used musical intervention in patients with AD to assess whether these therapeutic modalities were effective in assisting memory. To analyse this question, the authors performed a systematic review focusing on randomized trials.