Therapeutic efficacy of probiotics for symptoms of attention-deficit hyperactivity disorder in children and adolescents: meta-analysis.

2024-01
BJPsych open 10(1)

PubMed: 38268113
DOI: 10.1192/bjo.2023.645

Study Design

Type: Review
Sample size: n = 379
Population: seven trials involving 379 participants (mean age 10.37 years, range 4-18 years)
Methods: Meta-analysis of seven randomized placebo-controlled trials identified through searching major databases from inception to April 2023

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.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Lactobacillus casei PXN 37	—	Improved ADHD-Related Symptoms	Neutral	Small	View source Meta-analysis of seven trials involving 379 participants ... 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.
Lactobacillus rhamnosus PXN 54	—	No Significant Improvement in ADHD Symptoms	Neutral	Small	View source Meta-analysis of seven trials involving 379 participants ... showed no significant improvement in total symptoms of ADHD ... symptoms of inattention ... or hyperactivity/impulsivity ... between the probiotic and placebo groups.