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

Purpose Accumulating evidence highlights the importance of microbiota-directed intervention in neuropsychiatric disorders. This study aims to investigate the effects of probiotic supplements as an adjunct therapy in combination with Ritalin in children with attention-deficit hyperactivity disorder (ADHD). Design/methodology/approach Children with ADHD, aged 6-12 years, who had an intelligent quotient of >= 70 were enrolled in the study. Participants were randomly assigned to either the group that received probiotics or the group that received the placebo in addition to the weight-adjusted dose of Ritalin. Parents were asked to complete the revised Conners Parent Rating Scale-short version (CPRS-RS), and the psychiatrist completed the seven-point Clinical Global Impression-Severity (CGI-S) scale. Two study groups were compared in three time points, including T1 (before intervention), T2 (at the end of fourth week) and T3 (at the end of the eighth week). Findings A total of 38 participants completed the study. After eight weeks of intervention, the probiotic group had a significant improvement regarding CPRS-RS scores in T2 (9.4 unit, p = 0.014) and T3 (18.6 unit, p < 0.001), compared to placebo. In addition, children in the probiotic group had 0.7 unit lower CGI in T3 (p = 0.018) than the placebo group. A significant reduction of CGI scores was observed in each interval (T2 vs T1, T3 vs T2 and T3 vs T1; p < 0.05). This significant change in CGI score between intervals was also detected in the placebo group in T2 vs T1 (p = 0.002) and T3 vs T1 (p < 0.001). Mean CPRS scores of the groups were different in T2 and T3 (p = 0.011 and p < 0.001, respectively) and mean CGI scores of the two study groups were different in T3 (p = 0.018). Originality/value Eight weeks of supplementation with probiotics had a favorable effect on symptoms and severity of ADHD. Therefore, probiotics as an adjuvant treatment might have a promising efficacy regarding the management of ADHD.