Therapeutic Effects of Probiotics on Symptoms of Anxiety in Children and Adolescents: A Systematic Review and Meta-Analysis of Placebo-Controlled Trials

Abstract

Objective:

The current study aimed to investigate the efficacy of probiotics in alleviating anxiety in children and adolescents.

Methods:

Randomized placebo-controlled trials (RCTs) recruiting children and adolescents were identified through searching major databases using the main keywords “Probiotics” and “Anxiety.” Outcomes included improvement in anxiety and treatment acceptability. Continuous and categorical data were expressed as effect size based on standardized mean difference (SMD) and odds ratios (ORs), respectively, with 95% confidence intervals.

Results:

Meta-analysis of seven RCTs involving 912 participants (mean age = 8.21) showed no significant improvement in anxiety (SMD = −0.09, p = 0.54) between the probiotics and placebo groups. However, subgroup analysis revealed probiotics-associated anxiety improvement (SMD = −0.55, p = 0.02) in studies enrolling individuals with neurodevelopmental disorders but not in those without (SMD = 0.12, p = 0.48). A significant difference was noted between studies recruiting participants with such diagnoses and those without (SMD = −0.55 vs. 0.12, p = 0.05). Moreover, probiotics-related improvement in anxiety was found in individuals diagnosed with autism spectrum disorder (ASD) (SMD = −0.35, p = 0.03) but not attention deficit hyperactivity disorder (ADHD) (SMD = −0.21, p = 0.38). Overall dropouts exhibited no difference between the probiotics and placebo groups (OR = 0.90, p = 0.36).

Conclusion:

Our results showed efficacy of probiotics against anxiety compared with placebos only in participants diagnosed with neurodevelopmental disorders, especially ASD. Nevertheless, insufficient evidence derived from limited studies (i.e., three trials for ASD and two for ADHD) requires further investigations for verification.