Treating impulsivity with synbiotics in adults: a multicentre, double-blind, randomized, placebo-controlled trial

Introduction Impulsivity and compulsivity are related to emotional and social maladjustment and often underlie psychiatric disorders. Alterations in microbiota composition demonstrated implications for brain development and social behaviour via the microbiota-gut-brain axis. Recent evidence suggests the modulatory effect of synbiotics on gut microbiota which could ameliorate symptoms of psychiatric diseases. No randomized-controlled trial has been performed yet to investigate effects of synbiotics on impulsivity and compulsivity.

Methods In a prospective, multicentre, double-blind, randomized-controlled trial patients receive either a synbiotic formula or placebo treatment. Primary outcomes include Clinical Global Impression-Improvement (CGI-I) score of 1 or 2 = very much or much improved, and Affective Reactivity Index (ARI-S) score reduction of minimally 30% compared to baseline. N = 180 highly impulsive participants, 18 – 65 years old, diagnosed with attention deficit/hyperactivity disorder (ADHD) and/or borderline personality disorder (BPD), are screened at three study centres. Secondary outcome measures include changes in general psychopathology, ADHD symptoms, neurocognitive functions, somatic parameters, physical activity, nutritional intake and health-related quality of life. Intervention effects on microbiome, genetics and several blood biomarkers will be also assessed.

Results We hypothesize that the supplementation with synbiotics is an effective treatment in adults with high levels of impulsivity, compulsivity, and aggression, ameliorating these symptoms. Current stage of work: Data collection.

Conclusion This first randomized-controlled trial investigating synbiotics effects on reducing impulsive, compulsive and aggressive behaviour can help explain the crosstalk between intestinal microbiome and brain. If improvement effects are demonstrated, new cost-effective treatments might be available to these patients.