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Greetings, this is David Rosenberg. In this Smart Take, we will explore the intersection of traditional psychotropic medication and alternative medication—probiotics in this case. The authors investigated the therapeutic efficacy of probiotics for symptoms of ADHD in children and adolescents. This is a comprehensive meta-analysis, scrutinizing randomized placebo-controlled trials from various databases until April 2023. Nearly 380 participants with ADHD were examined in this meta-analysis; the findings were intriguing.
Firstly, it must be noted that there was no evidence showing therapeutic efficacy of probiotics alone for ADHD symptoms. However, despite not being statistically significant, there was a substantial difference in effect size where probiotics were used as an adjunct to methylphenidate and when utilized as supplementation. Furthermore, there appeared to be a moderate difference—an increased effect size—when multiple strains of probiotics were employed. Therefore, even though current evidence does not indicate a significant difference in therapeutic efficacy between probiotics and placebo in treating pediatric ADHD, there exists an intriguing nonsignificant trend showing therapeutic efficacy associated with multistrain probiotics or when combined with methylphenidate. This could potentially provide an exciting area for future research.
It is important to recognize that complementary approaches and treatments, such as probiotics, are being used frequently; hence it is necessary to study them meticulously as they are already prevalent. There are numerous individuals—parents included—who strongly believe in the role of complementary medicine, often perceived as more “natural” treatments. It is crucial to analyze this scientifically. Despite knowing how effective stimulants and ADHD medication can be, it is also true that approximately 30% of patients do not respond at all to current ADHD medication—even stimulants—and numerous others respond incompletely or insufficiently. There can be problematic side effects and other challenges linked with comorbidity; therefore, we have not reached the end of ADHD treatment methods yet. There is more to explore.
However, there remains significant controversy regarding this matter, and, currently, no definitive study proves significant improvement in ADHD symptoms using probiotics.
It is also necessary to explore additional alternatives for ADHD treatment. Probiotics are not the only possible treatment; there has been a substantial focus on gut microbiome–brain interactions. The chemistry and functioning in the gut and brain are remarkably similar; therefore, it is imperative that we examine this meticulously. Although results failed to demonstrate superior efficacy of probiotics for treating ADHD symptoms compared with placebo, there were a limited number of eligible trials. Thus, we cannot rule out the possibility of this being a potential avenue for treatment—especially because nonsignificant trends suggested multiple-strain probiotics having therapeutic efficacy in ADHD and using probiotic adjunctive therapy with methylphenidate.
Again, I wish to emphasize that this was not a statistically significant finding. However, I believe future studies are warranted—possibly alongside biological studies examining the gut microbiome’s diversity or lack thereof—in ADHD and how it may relate to treatment response or lack thereof. This is a vast area of research in psychiatry, extending to autism, obsessive-compulsive disorder, tic disorders, and depression. Given how common ADHD is, although this preliminary examination does not show an overwhelming or even statistically significant effect, I consider this an important understudied area deserving future research.
Abstract
Therapeutic Efficacy of Probiotics for Symptoms of Attention-Deficit Hyperactivity Disorder in Children and Adolescents: Meta-Analysis
Shun-Chin Liang, Cheuk-Kwan Sun, Chih-Hua Chang, Yu-Shian Cheng, Ruu-Fen Tzang, Hsien-Jane Chiu, Ming Yu Wang, Ying-Chih Cheng, Kuo-Chuan Hung
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.
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Reference
Liang, S., Sun, C., Chang, C., Cheng, Y., Tzang, R., Chiu, H., Wang, M. Y., Cheng, Y., & Hung, K. (2024). Therapeutic efficacy of probiotics for symptoms of attention-deficit hyperactivity disorder in children and adolescents: Meta-analysis. BJPsych Open, 10(1).
