Breaking boundaries: A systematic review of the application of non-invasive brain stimulation symptoms and sleep parameters in people with ADHD

Background: Studies of non-invasive treatments such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) can contribute in an alternative way to the symptoms treatment and changes in sleep patterns in attention deficit hyperactivity disorder (ADHD), due to some scientific evidence of action on cognition and clinical characteristics.

Aim: The aim of this systematic review was to evaluate studies of non-invasive brain stimulation using rTMS and tDCS on symptoms and sleep parameters in people with ADHD, in order to synthesize the main findings on intervention effects.

Methodology: A systematic review was carried out using the PRISMA protocol in the PubMed/Medline, Embase, PsycInfo, CINAHL, PEDro and Central-Cochrane library databases were initially carried out on 14 March 2024 and repeated until September 2024. Randomized clinical trials evaluating the effect of rTMS and tDCS on symptoms and changes in sleep pattern in people with ADHD were included. Primary outcomes were total severity of ADHD symptoms and sleep quality assessed by questionnaires and instrument measures.

Results: The review evidenced only positive findings in five studies for tDCS in some cognitive functions, ADHD symptoms and improvement in sleep parameters, being results with reduced efficacy due to the high heterogeneity in the experimental protocols.

Conclusion: The findings show limited evidence; however, it is suggested that the combined use of non-invasive stimulation with other approaches, such as cognitive training, may improve the intervention effect. It is also important to consider limitations such as heterogeneity in clinical protocols, selection of participants with ADHD, including dosage and frequency. These factors should be explored in future research to optimize the application of these therapies.