Abstract
Background
The efficacy of probiotics as a therapeutic alternative for attention-deficit hyperactivity disorder (ADHD) remain unclear.
Aims
To investigate the effectiveness of probiotics for symptoms of ADHD and identify possible factors affecting their efficacy.
Method
Randomised placebo-controlled trials were identified through searching major databases from inception to April 2023, using the main keywords ‘probiotics’ and ‘ADHD’ without limitation on languages or geographic locations. The outcome of interest included improvement in total symptoms of ADHD, symptoms of inattention and hyperactivity/impulsivity, and drop-out rate. Continuous and categorical data were expressed as effect sizes based on standardised mean differences (SMDs) and odds ratios, respectively, with 95% confidence intervals.
Results
Meta-analysis of seven trials involving 379 participants (mean age 10.37 years, range 4–18 years) showed no significant improvement in total symptoms of ADHD (SMD = 0.25; P = 0.12), symptoms of inattention (SMD = 0.14; P = 0.3) or hyperactivity/impulsivity (SMD = 0.08; P = 0.54) between the probiotic and placebo groups. Despite non-significance on subgroup analyses, there was a large difference in effect size between studies using probiotics as an adjunct to methylphenidate and those using probiotics as supplementation (SMD = 0.84 v. 0.07; P = 0.16), and a moderate difference in effect size between studies using multiple strains of probiotics and those using single-strain regimens (SMD = 0.45 v. 0.03; P = 0.19).
Conclusions
Current evidence shows no significant difference in therapeutic efficacy between probiotics and placebos for treatment of ADHD symptoms. However, albeit statistically non-significant, higher therapeutic efficacies associated with multiple-strain probiotics or combining probiotics with methylphenidate may provide direction for further research.
Publisher
Royal College of Psychiatrists
Subject
Psychiatry and Mental health
Reference46 articles.
1. Probiotic supplement as an adjunctive therapy with ritalin for treatment of attention-deficit hyperactivity disorder symptoms in children: a double-blind placebo-controlled randomized clinical trial;Ghanaatgar;Nutr Food Sci,2022
2. A systematic review of microbiome changes and impact of probiotic supplementation in children and adolescents with neuropsychiatric disorders;Ligezka;Prog Neuropsychopharmacol Biol Psychiatry,2021
3. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve;Bravo;Proc Natl Acad Sci U S A,2011
4. Gut microbiota and probiotic therapy in ADHD: a review of current knowledge;Kalenik;Prog Neuropsychopharmacol Biol Psychiatry,2021
5. Reduced microbiome alpha diversity in young patients with ADHD;Prehn-Kristensen;PLoS One,2018