Probiotics as a Promising Therapy in Improvement of Symptoms in Children With ADHD: A Systematic Review

BACKGROUND: ADHD is widely recognized as the most prevalent neurodevelopmental disorder in children. Recently, the potential role of gut microbiota as an etiological factor in ADHD has gained attention. This systematic review aims to investigate the potential impact of probiotic supplements on alleviating ADHD symptoms and influencing behavior. METHODS: PubMed, Web of Science, Cochrane Library, and SCOPUS were searched from inception to May 2023. Only randomized controlled trials that have suitable data of the effects of probiotics/synbiotics on children with ADHD were enrolled. The risk of bias of the included studies was assessed by Cochrane Collaboration risk of bias tool. RESULTS: Five related randomized controlled trial were evaluated in the current review. Types of interventions ranged from single/multi strain probiotics to synbiotic. The duration of intervention in all of the studies were 2 to 3 months. The assessed outcomes were very diverse and different tools were used to report the symptoms in children. Among those which used Conners' Parent Rating Scale, a decrease in the total score occurred in the probiotic group, compared to the placebo group. An improvement in both intervention and control groups was seen in one study which used ADHD-Rating Scale. CONCLUSION: In summary, the combined findings from the reviewed studies suggest that probiotic supplements might potentially serve as a complementary intervention for ADHD. However, given the small number of studies, limited sample sizes, and the diversity of probiotic strains, further research is needed to clarify the effects of probiotics in children with ADHD. The observed tolerability of probiotics is noteworthy as none of the studies report adverse effects.