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March 17, 2025
Background:
Noting that “the results of previous investigations into the therapeutic benefits of probiotics in the treatment of ADHD symptoms remain inconsistent,” a Taiwanese study team conducted a systematic search of the peer-reviewed medical literature to perform a meta-analysis.
The Study:
The team identified seven randomized controlled trials (RCTs) that met criteria for inclusion: focusing on children and adolescents under 18, with ADHD diagnoses, comparing probiotic interventions with placebo, and using standardized behavioral rating scales to assess ADHD symptoms.
Meta-analysis of these seven RCTs with a combined total of 342 participants found no significant improvement in ADHD symptoms. In fact, six of the seven RCTs clustered tightly around zero effect, while the seventh – a small sample (38) outlier – reported a very large effect size improvement.
Meta-analysis of the three RCTs with a combined 154 individuals that used probiotics with single strains of microorganisms showed absolutely no improvement in ADHD symptoms with no between-study variation (heterogeneity).
Meta-analysis of the four RCTs with a total of 188 participants that used multiple strains pointed to a medium – but statistically nonsignificant – effect size improvement, with high heterogeneity. Removing the previously mentioned outlier RCT collapsed the effect size to zero.
Two of the RCTs (with 72 total individuals), including the outlier, offered probiotics in conjunction with methylphenidate treatment. Meta-analysis of the other five RCTs with 270 persons that were structured around pure supplementation yielded absolutely no improvement in ADHD symptoms with no heterogeneity.
Meta-analyses of the four RCTs with a combined total of 238 participants that examined ADHD subtypes reported no effect on either inattention symptoms or hyperactivity/impulsivity symptoms.
Trivially, given the lack of efficacy, probiotic regimens were tolerated as well as placebo.
The Take-Away:
Ultimately, this meta-analysis found no evidence that probiotics improve ADHD symptoms in children and adolescents. Across seven randomized controlled trials, results consistently showed no significant benefit compared to a placebo. While probiotics were well-tolerated, they did not meaningfully impact inattention, hyperactivity, or impulsivity. These findings suggest that probiotics, whether single or multi-strain, are not an effective treatment for ADHD.
Shun-Chin Liang, Cheuk-Kwan Sun, Chih-Hua Chang, Yu-Shian Cheng, Ruu-Fen Tzang, Hsien-Jane Chiu, Ming Yu Wang, Ying-Chih Cheng, and Kuo-Chuan Hung, “Therapeutic efficacy of probiotics for symptoms of attention-deficit hyperactivity disorder in children and adolescents: meta-analysis,” BJPsych Open (2024) 10, e36, 1–8, https://doi.org/10.1192/bjo.2023.645.
Folic acid, also known as folate, is an essential vitamin(B-9). Inadequate dietary folate has been associated with abnormal fetal brain development. That suggests a deficiency could contribute to neurodevelopmental disorders, including ADHD.
If so, could folic acid supplementation for pregnant mothers help avoid ADHD in offspring?
A Chinese study team conducted a systematic search of the peer-reviewed medical journal literature looking for studies exploring neurodevelopmental effects associated with such supplementation.
It identified six studies that specifically looked for associations with offspring ADHD. A meta-analysis of these studies encompassing a total of 29,634 participants found a 14% (one in seven) reduction in the odds of ADHD in the offspring of mothers taking folate supplementation as opposed to children of mothers not doing so.
There was no sign of either publication bias or between-study heterogeneity.
The authors concluded, "Our meta-analysis indicated that appropriate maternal FA supplementation may have positive effects on offspring's neurodevelopmental outcomes, including improved intellectual development and reduced risk of autism traits, ADHD, behavioral, and language problems."
Given that folate is an essential vitamin in the first place, this suggests ensuring that pregnant women supplement their diet with folic acid. The authors further counseled, "However, further high-quality studies on this topic are needed to confirm the optimal dosage and the right time of FA supplementation and to investigate the underlying mechanisms."
Stimulant medications like methylphenidate and amphetamines are well-established treatments for reducing ADHD symptoms, making a notable difference in focus and behavior. Given that caffeine is also a stimulant, researchers have wondered whether it might offer similar benefits for managing ADHD symptoms. A recent meta-analysis conducted by a Brazilian research team sought to explore this question.
The researchers faced an immediate challenge: there is surprisingly little research directly investigating caffeine's effects on ADHD symptoms. After a thorough review of peer-reviewed literature, they identified only four randomized controlled trials (RCTs) suitable for their analysis, encompassing a combined total of just 152 participants.
The limited number of studies—and participants—meant that the meta-analysis was not as robust as the research team might have hoped. However, they proceeded to examine the available data to determine whether caffeine showed any measurable benefit over a placebo.
The results of the meta-analysis showed a slight decrease in ADHD symptoms among those who consumed caffeine compared to those given a placebo. However, this reduction was not statistically significant. The small sample size likely played a role in this outcome, making the study underpowered. Even if future studies with larger groups of participants were to show statistical significance, the observed effect size would likely remain too small to be clinically meaningful.
Interestingly, the four trials included in the meta-analysis showed very little variation in their findings. Each study slightly favored caffeine over placebo, but none came close to achieving statistical significance.
Ultimately, the researchers concluded that “overall, the totality of the evidence suggests no significant benefit of caffeine over placebo in the treatment of children with ADHD.” The findings indicate that while caffeine might produce a slight reduction in symptoms, it is not an effective alternative to established ADHD treatments like methylphenidate or amphetamines.
This study highlights the importance of relying on proven medications for ADHD management rather than seeking alternatives that lack substantial evidence. While caffeine might offer a slight stimulant effect, it falls short of delivering the therapeutic benefits needed for those with ADHD to manage their symptoms effectively. For clinicians, parents, and individuals with ADHD, these results underscore the value of evidence-based treatments in improving quality of life and daily functioning.
Noting that “Oxidative stress disrupts the structure and function of neurons in the prefrontal lobe of the brain,” and “Structural and functional impairments in the prefrontal cortex have been shown to be highly correlated with behavioral and emotional problems of ADHD,” a Chinese team at Dalian University set out to systematically evaluate the safety and efficacy of antioxidant therapy in children and adolescents with ADHD.
The team’s systematic search of the peer-reviewed medical literature identified a total of 48 randomized controlled trials (RCTs) or prospective studies involving 12 antioxidant agents (resveratrol, pycnogenol, omega-3, omega-6, quercetin, phosphatidylserine, almond, vitamin D, zinc, folic acid, ginkgo biloba, Acetyl-L-carnitine) that met criteria for inclusion:
Treatment efficacy was measured through ADHD symptom scores using Conners’ parent rating scale (CPRS), Conners’ teacher rating scale (CTRS), ADHD rating scale-parent (ADHD RS-Parent), and ADHD rating scale-teacher (ADHD RS-Teacher), as well as secondary outcome indicators such as the Clinical Global Impressions scale (CGI) and Continuous Performance Test (CPT), relative to controls.
None of the antioxidant therapies were significantly better than placebo.
One limitation is that no effort was made to assess publication bias.
These results indicate that antioxidants should not be used for treating ADHD.
Vitamins play important roles in metabolism, immune regulation, and neurodevelopment. Recent studies show that deficiencies in vitamins like D, B6, B12, and folate are common in people with ADHD and ASD (autism spectrum disorder), and are associated with behavioral, cognitive, and brain development issues.
The Study:
A study team based in China has just performed a systematic search of the peer-reviewed medical literature to perform meta-analyses of clinical trials exploring vitamin interventions in the treatment of ADHD and ASD.
ADHD trials included participants with an official diagnosis. The primary intervention was vitamin supplements, while other treatments, including medications, remained unchanged or were excluded during the study period. ADHD outcomes included measurable changes in ADHD symptoms using validated rating scales and executive function measures.
Eligible studies included standard or sham control groups, crossover, parallel, or other clinical trial designs. In crossover studies, only first-phase data were analyzed to prevent carryover effects.
Ten trials with 852 participants met the standards, but meta-analysis showed no significant results. The outcomes varied widely, suggesting a need to distinguish among vitamins.
Results:
Of the five trials involving 347 participants that specifically evaluated vitamin D supplementation, results indicated a large effect size improvement in ADHD symptoms and executive function measures. The other five studies did not show any observable improvement.
Key limitations include:
The team concluded, “This meta-analysis supports the use of vitamin supplementation as a promising adjunctive treatment for ASD and ADHD. Vitamin B showed greater benefits in improving symptoms of ASD, while vitamin D was more effective in managing ADHD-related behaviors. These findings suggest that specific vitamins may target disorder-specific symptoms. Despite limitations such as the lack of trials on other vitamins and limited understanding of underlying mechanisms, vitamin therapy remains a low-cost, accessible option.”
An important limitation of this work is that the positive results for vitamin D were due to two studies from Iran. So far, no positive study has emerged from a non-Iranian study.
Interpretation:
The vitamin D findings are intriguing and could be important if replicated outside of Iran. Since supplementation is already widely recommended to those with limited sunlight exposure, clinicians may want to consider monitoring their patients’ vitamin D intake, especially in the winter months. It should be noted, however, that due to the limitations of this study, the results are by no means conclusive, and vitamin D should not be taken as a stand-alone treatment for ADHD.
Claims-based real-world data can reveal population-level trends in health among people with neurodevelopmental disorders. This new study examined the prevalence, demographics, and chronic comorbidities of adults and of children and adolescents with ADHD in a large national health plan. It also compared healthcare use and costs between those with and without ADHD.
A research team in the United States conducted an observational cohort study using claims data from more than 1.9 million adults and nearly 500,000 children and adolescents, comparing individuals diagnosed with ADHD to those without the diagnosis.
ADHD was diagnosed in 4% of adults and in 5% of children and adolescents.
Comorbidities By The Numbers:
Disruptive childhood disorders are behavioral problems marked by ongoing defiance, uncooperativeness, and aggression that affect a child's daily life and relationships. The main types, oppositional defiant disorder (ODD) and conduct disorder (CD), involve persistent anger and argumentativeness in ODD, and more severe actions like aggression, cruelty, and criminal behavior in CD. Without treatment, these common childhood disorders can continue into adulthood and raise the risks of substance use, violence, incarceration, and early death.
Disruptive childhood disorders were twenty times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and fifteen times more frequent among adults with ADHD.
Bipolar disorder was twelve times more common among children and adolescents with ADHD than those without ADHD, and seven times more common among adults with ADHD.
Schizophrenia was eleven times more prevalent among children and adolescents with ADHD than those without ADHD, and three-and-a-half times more common among adults with ADHD.
Anxiety was nine times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and more than five times more frequent among adults with ADHD.
Depression was eight times more common among children and adolescents with ADHD than those without ADHD, and more than five times more common among adults with ADHD.
Suicidal ideation was eight times more prevalent, and suicide attempt seven times more prevalent, among children and adolescents with ADHD than those without ADHD. Both suicidal ideation and suicide attempt were five times more common among adults with ADHD.
Gender dysphoria was almost six times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and five times more frequent among adults with ADHD.
Eating disorders were over four times more common among children and adolescents with ADHD than those without ADHD, and five times more common among adults with ADHD.
Substance-related disorders were over six times more prevalent, and alcohol use disorder was six times more prevalent among children and adolescents with ADHD than those without ADHD, and four and three times more prevalent among adults with ADHD.
Increased Costs of Medical Care:
These comorbidities and ADHD led to higher medical costs. Children and adolescents with ADHD spent $610 more annually on healthcare than those without, while adults with ADHD had $1,684 higher average yearly expenditures than non-ADHD adults.
The Take-Away:
This large claims-based analysis of a national commercial insurer found ADHD diagnoses in roughly 4% of adults and 5% of children. It documented substantially higher rates of co-occurring behavioral-health conditions and markedly greater healthcare utilization and expenditures among those with ADHD. The authors report increased odds for several co-occurring diagnoses, as well as higher per-member-per-month (PMPM) spending and per-thousand-per-month (PTPM) utilization, largely driven by greater use of behavioral health services.
Importantly, these results come from cross-sectional, claims data within a commercially insured population: they describe associations, not causal relationships, and may not generalize to uninsured, publicly insured, or otherwise different populations. These findings, therefore, warrant cautious interpretation and highlight the need for longitudinal and more representative studies to clarify drivers of the increased burden and to inform care and policy.
Background:
Since the first in vitro fertilization (IVF) in 1978, assisted reproductive technology (ART) has led to over 10 million births worldwide.
There are four types of embryo transfers, depending on whether they are fresh or frozen, and on their developmental stage.
Fresh cleavage stage embryos are transferred on day 2 or 3 following fertilization and typically contain four to eight relatively large, undifferentiated cells. Fresh blastocyst embryos are transferred on day 5 or 6 after fertilization. At this point, they have developed over a hundred cells and have differentiated into two types: the inner cell mass, which develops into the fetus, and the outer cell layer, which forms the placenta.
Globally, more children are now born through assisted reproductive technology using frozen-thawed embryo transfer than fresh embryo transfer.
Research suggests that ART-conceived offspring may face increased risks of cardiovascular, musculoskeletal, chromosomal, urogenital diseases, and cancers. Might they also be at increased risk for ADHD?
Study:
Taiwan’s single-payer health insurance covers over 99% of people and records all their healthcare activity. Since 1998, it has kept an ART database for all couples registered for IVF treatment.
A Taiwanese research team reviewed all records for the five-year period from 2013 through 2017, ultimately analyzing 3,125 live singleton births from fresh cleavage stages, 1,332 from fresh blastocysts, 1,465 from frozen cleavage stages, and 4,708 from frozen blastocysts, alongside 878,643 naturally conceived singleton births.
The team controlled for the following potential confounders: pregnancy-induced hypertension, chronic hypertension, diabetes mellitus, gestational diabetes mellitus, unhealthy lifestyle, placenta previa, placenta abruption, preterm premature rupture of membrane, and postpartum hemorrhage.
Results:
With these adjustments, cleavage stage embryo transfers, whether fresh or frozen, were associated with a seven-fold higher rate of ADHD diagnosis in offspring than natural conception.
Frozen blastocyst embryo transfers were likewise linked to a seven-fold increase in ADHD diagnoses in offspring compared to natural conception. Notably, fresh blastocyst transfers showed a 19-fold increase, likely due to the smaller number of cases in this category.
The team concluded, “Compared to natural conception, ART is associated with higher risks, particularly for preterm birth, ADHD, and developmental delay.”
Conclusion:
This large national cohort suggests that ART-conceived singletons face higher rates of several adverse outcomes, including preterm birth, ADHD, and developmental delay. Clinicians and prospective parents should therefore weigh these potential associations when counseling and planning care, prioritize optimized ART protocols and perinatal management, and ensure early developmental surveillance for ART-conceived children so concerns can be identified and addressed promptly.
It is important to note that the findings also point to the likely contribution of underlying parental infertility in these developmental outcomes. Future research should aim to disentangle parental- versus procedure-related risks to clarify absolute risk magnitudes. As always, associations of this time should not be interpreted as causal due to the inability of observational studies to rule out all possible confounding factors.
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