Mental disorders affect nearly one billion people worldwide, posing major challenges to public health. While conventional treatments like psychotherapy and pharmacotherapy are effective for many patients, they are often associated with adverse effects and high non-response rates, underscoring the need for alternative approaches. Non-invasive brain stimulation techniques such as transcranial magnetic stimulation, transcranial electric stimulation and transcranial focused ultrasound stimulation are increasingly used to treat psychiatric conditions. Although these methods show promising efficacy, data on their adverse effects remain fragmented and inconsistently reported. This meta-analysis aims to systematically compare the type and frequency of adverse effects, tolerability, and acceptability across different brain stimulation techniques and mental disorders. The findings will help improve safety monitoring and support more personalised, well-tolerated treatment strategies.

A systematic literature search of the Embase, MEDLINE(R), AMED (Allied and Complementary Medicine) and APA PsycINFO via OVID will be performed. Eligible studies include randomised controlled trials (RCTs) that compare active treatments or an active treatment with sham control, including both parallel group and cross-over studies, as well as prospective non-randomised studies such as case–control studies and pre–post studies investigating adverse effects of non-invasive brain stimulation in psychiatric populations. Included studies report on the frequency of adverse effects in a standardised manner. Primary outcomes comprise the incidence of specific adverse effects, dropout rates due to adverse effects (tolerability) and overall dropout rates (acceptability). Risk of bias will be assessed using the Cochrane RoB 2.0 tool for RCTs and the NHLBI quality assessment tool for pre–post studies. The quality of case–control studies will be assessed using the Newcastle-Ottawa scale. Provided that sufficient data are available and the network of comparisons is adequately connected, a network meta-analysis will be conducted to compare adverse effects and tolerability across interventions.

No ethical approval is needed to conduct this work. The findings will be submitted for publication in peer-reviewed journals and presented at scientific meetings.

CRD420251164554

The number of people living with dementia is increasing worldwide. Alzheimer’s disease (AD) is the most common type of dementia. It typically manifests itself initially with cognitive impairment in the memory domain and gradually progresses towards affecting all activities of daily living. Active music interventions, particularly singing, may improve mood, social behaviour and quality of life. However, little is known about their effects on cognition, although some studies have provided promising results. The Memory for Music (M4M) project aims to fill this gap in research by measuring the effects of learning new songs on cognitive functioning. Specifically, M4M will examine memory for new songs in non-musician adults with AD after undergoing intensive versus minimal individual musical training based on singing novel songs.

Home-dwelling adults with AD, 65 years or older, will receive 5 months of intensive intervention (2x/week) and 5 months of minimal intervention (1x/month). In a crossover design, participants will be randomised to receive either the intensive or minimal intervention first, with 2 months between the intervention periods. Participants will receive individual music lessons to learn new songs, provided by a music instructor with adequate training. The main outcomes will be measured at the beginning and end of each intervention period. General cognition will be measured with the AD Assessment Scale – Cognitive by an assessor blinded to the randomisation. Participants’ memory for music will be measured using the N400 component of electroencephalographic (EEG) event-related potentials in response to music stimuli. Additional outcomes evaluated during intervention sessions include mood and musical performance observations. With 113 participants randomised, the trial will have 80% power to detect clinically meaningful effects. Relations between mood, memory for music and cognitive abilities will be examined, with sex, age, AD stage, previous musical training and education as covariates. M4M will be conducted in close collaboration between academic researchers, service providers and service users to ensure relevance and applicability.

Dissemination of findings will apply to local, national and international levels. The study has been approved by the Regional Committees for Medical and Health Research Ethics in Norway (reference number 759936) and by Mautalén Salud e Investigación, CECOM in Argentina (register code 14412).

Clinicaltrials.gov, NCT06611878.