Meta-analysis Reports No Significant Evidence for Efficacy of Neuromechanistic Treatments for Adult ADHD

The Background on ADHD Treatments, rTMS and tDCS:

Methylphenidate is known as the gold-standard treatment for ADHD, increasing dopamine concentrations and helping to focus. However, these psychostimulants may be less well-tolerated in adults. Adverse effects include decreased appetite, nausea, racing heartbeat, restlessness, nervousness, and insomnia. 

Neurofeedback is a non-pharmaceutical treatment that combines cognitive behavioral therapy techniques like conditioning and positive reinforcement with electroencephalography (EEG) feedback. Electrodes are placed on specific brain areas, guiding patients to regulate their brainwave activity. 

Repetitive transcranial magnetic stimulation (rTMS) uses electromagnetism to induce an electric field by passing a magnetic field through the scalp. Transcranial direct current stimulation (tDCS), on the other hand, directly applies an electric current through the scalp. Both repetitive transcranial magnetic stimulation (rTMS) and tDCS primarily target the outermost layers of neurons, as they are non-invasive methods. Nevertheless, both techniques are believed to affect deeper layers through interconnected neuronal networks.  

The Study:

A French research team conducted a systematic search of the peer-reviewed medical literature to perform a meta-analysis to explore the efficacy of these experimental treatment techniques. 

Eight studies – four using rTMS and another four using tDCS – met the inclusion criteria. Studies had to be randomized controlled trials (RCTs), and had to involve multiple sessions of treatment. Participants had to be adults previously diagnosed with ADHD.  

Outcomes were measured through self-rated scales, neuropsychological tests, and electrophysiological pre-post evaluations. 

Separate meta-analyses of the four tDCS RCTs combining 154 participants and of the four rTMS RCTs encompassing 149 participants likewise reported no significant improvements. In all cases variation in outcomes between studies was moderate, and there were no signs of publication bias. 

The Conclusion on Neuromechanistic Treatments for ADHD:

Meta-analysis of all eight studies with a combined total of 421 participants reported no significant improvements over controls. Narrowing down to studies that used sham controls likewise produced no significant improvements. So, despite the title of this study, these neuromechanistic treatments do not appear to be the future of treatment for adult ADHD.

Margaux Courrèges, Marie Hoareau, Carole Levenes, and Hassan Rahioui, “Comparative efficacy of neurofeedback, tDCS, and TMS: The future of therapy for adults with ADHD. A systematic review and meta-analysis,” Journal of Affective Disorders (2025), 388: 119585, https://doi.org/10.1016/j.jad.2025.119585

Related posts

Transcranial Direct Current Stimulation: Can It Treat ADHD?

How effective and safe is transcranial direct current stimulation for treating ADHD?

ADHD is hypothesized to arise from 1) poor inhibitory control resulting from impaired executive functions which are associated with reduced activation in the dorsolateral prefrontal cortex and increased activation of some subcortical regions; and 2)hyperarousal to environmental stimuli, hampering the ability of the executive functioning system, particularly the medial frontal cortex, orbital and ventromedial prefrontal areas, and subcortical regions such as the caudate nucleus, amygdala, nucleus accumbens, and thalamus, to control the respective stimuli.

These brain anomalies, rendered visible through magnetic resonance imaging, have led researchers to try new means of treatment to directly address the deficits. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that uses a weak electrical current to stimulate specific regions of the brain.

Efficacy:

A team of researchers from Europe and ran performed a systematic search of the literature and identified fourteen studies exploring the safety and efficacy of tDCS. Three of these studies examined the effects on ADHD symptoms. They found a large effect size for the inattention subscale and a medium effect size for the hyperactivity/impulsivity. Yet, as the authors cautioned, "a definite conclusion concerning the clinical efficacy of tDCS based on the results of these three studies is not possible."

The remaining studies investigated the effects on specific neuropsychological and cognitive deficits in ADHD:

  •  Working memory was improved by anodal stimulation - but not cathodal stimulation - of the left dorsolateral prefrontal cortex. Anodal stimulation of the right inferior frontal gyrus had no effect.
  •  Response inhibition: Anodal stimulation of the left or right dorsolateral prefrontal cortex was more effective than anodal stimulation of the bilateral prefrontal cortex.
  • Motivational and emotional processing was improved only with stimulation of both the dorsolateral prefrontal cortex and orbitofrontal cortex.

The fact that heterogeneity in the methodology of these studies made meta-analysis impossible means these results, while promising, cannot be seen as in any way definitive.

Safety:

Ten studies examined childhood ADHD. Three found no adverse effects either during or after tDCS. One study reported a feeling of "shock" in a few patients during tDCS. Several more reported skin tingling and itching during tDCS. Several also reported mild headaches.

The four studies of adults with ADHD reported no major adverse events. One study reported a single incident of acute mood change, sadness, diminished motivation, and tension five hours after stimulation. Another reported mild instances of skin tingling and burning sensations.

To address side effects such as tingling and itching, the authors suggested reducing the intensity of the electrical current and increasing the duration. They also suggested placing electrodes at least 6 cm apart to reduce current shunting through the ski. For children, they recommended the use of smaller electrodes for better focus in smaller brains.

The authors concluded, "The findings of this systematic review suggest at least a partial improvement of symptoms and cognitive deficits in ADHD by tDCS. They further suggest that stimulation parameters such as polarity and site are relevant to the efficacy of tDCS in ADHD. Compared to cathodal stimulation, Anodal tDCS seems to have a superior effect on both the clinical symptoms and cognitive deficits. However, the routine clinical application of this method as an efficient therapeutic intervention cannot yet be recommended based on these studies ..."

January 10, 2022

What the MAHA Report Gets Right—and Wrong—About ADHD and Children's Health

The U.S. government released a sweeping document titled The MAHA Report: Making Our Children Healthy Again, developed by the President’s “Make America Healthy Again” Commission. Chaired by public figures and physicians with ties to the current administration, the report presents a broad diagnosis of what it calls a national health crisis among children. It cites rising rates of obesity, diabetes, allergies, mental illness, neurodevelopmental disorders, and chronic disease as signs of a generation at risk.

The report's overarching goal is to shift U.S. health policy away from reactive, pharmaceutical-based care and toward prevention, resilience, and long-term well-being. It emphasizes reforming the food system, reducing environmental chemical exposure, addressing lifestyle factors like physical inactivity and screen overuse, and rethinking what it calls the “overmedicalization” of American children.

While some of the report’s arguments are steeped in political rhetoric and controversial claims—particularly around vaccines and mental health diagnoses—others are rooted in well-established public health science. This blog aims to highlight where the MAHA Report gets the science right, especially as it relates to childhood health and ADHD.

Some of the Good Ideas in the MAHA Report:

Although the MAHA Report contains several debatable assertions, it also outlines six key public health priorities that are well-supported by decades of research. If implemented thoughtfully, these recommendations might make a meaningful difference in the health of American children:

Reduce Ultra-Processed Food (UPF) Consumption

UPFs now make up nearly 70% of children’s daily calories. These foods are high in added sugars, refined starches, unhealthy fats, and chemical additives, but low in nutrients. Studies—including a 2019 NIH-controlled feeding study—show that UPFs promote weight gain, overeating, and metabolic dysfunction.  What can help: Tax incentives for fresh food retailers, improved school meals, front-of-pack labeling, and food industry regulation.

Promote Physical Activity and Limiting Sedentary Time

Most American children don’t get the recommended 60 minutes of physical activity per day. This contributes to obesity, cardiovascular risk, and even mental health issues. Physical activity is known to improve attention, mood, sleep, and self-regulation.   What can help: Mandatory daily PE, school recess policies, walkable community infrastructure, and screen-time education.

Addressing Sleep Deprivation

Teens today sleep less than they did a decade ago, in part due to screen use and early school start times. Sleep loss is linked to depression, suicide risk, poor academic performance, and metabolic problems.  What can help: Later school start times, family education about sleep hygiene, and limits on evening screen exposure.

Improving Maternal and Early Childhood Nutrition

The report indirectly supports actions that are backed by strong evidence: encouraging breastfeeding, supporting maternal whole-food diets, and improving infant nutrition. These are known to reduce chronic disease risk later in life.

What MAHA Says About ADHD:

ADHD is one of the most discussed neurodevelopmental disorders in the MAHA Report, but many of its claims about ADHD are misleading, oversimplified, or inconsistent with decades of scientific evidence, much of which is described in the International Consensus Statement on ADHDand other references given below.

✔️ Accurate: ADHD diagnoses are increasing.

This is true. Diagnosis rates have risen over the past two decades, due in part to better recognition, broadened diagnostic criteria, and changes in healthcare access.  Diagnosis rates in some parts of the country are too high, but we don’t know why.  That should be addressed and investigated.  MAHA attributes increasing diagnoses to ‘overmedicalization’.   That is a hypothesis worth testing but not a conclusion we can draw from available data.

❌ Misleading: ADHD is caused by processed food, screen time, or chemical exposures.

These have been associated with ADHD but have not been documented as causes. ADHD is highly heritable, with genetic factors accounting for 70–80% of the risk.   Unlike genetic studies, environmental risk studies are compromised by confounding variables.   There are good reasons to address these issues but doing so is unlikely to reduce diagnostic rates of ADHD. 

❌ Inaccurate: ADHD medications don’t work long-term.

The report criticizes stimulant use but fails to note that ADHD medications are among the most effective psychiatric treatments, especially when consistently used.  They cite the MTA study’s long term outcome study of kids assigned to medication vs. placebo as showing medications don’t work in the long term.  But that comparison is flawed because during the follow-up period, many kids on medication stopped taking them and many on placebo started taking medications.   Many studies document that medications for ADHD protect against many real-world outcomes such as accidental injuries, substance abuse and even premature death.

How the MAHA Report Could Still Help People with ADHD:

Despite the issues discussed above, the MAHA Report can indirectly help children and adults with ADHD by pushing for systemic changes that reduce ultra-processed food consumption, increase physical activity, and motivate better sleep practices.

In other words, you don’t need to reject the diagnosis of ADHD to support broader changes in how we feed, educate, and care for children. A more supportive, less toxic environment benefits everyone—including those with ADHD.

May 28, 2025

Meta-analysis finds improvements in executive functioning in children and adolescents from non-pharmacological treatments, but with methodological shortcomings

Meta-analysis Finds Improvements in Executive Functioning From Some Non-Pharmacological ADHD Treatments

ADHD is associated with impaired executive functioning. Executive functions are a set of mental skills that include working memory, flexible thinking, and self-control. These are skills we use every day to learn, work, and manage daily life. Trouble with executive function can make it hard to focus, follow directions, and handle emotions. 

A Chinese study team searched for studies on non-pharmacological treatments of children and adolescents with ADHD aged 5 to 18 years intended to improve their executive functioning. 

An initial methodological weakness was the decision to combine studies using formal ADHD diagnoses based on professional psychiatric manuals (DSM 3/4/5 and ICD 10/11) and studies relying on other methods such as parent reports.

This lack of rigor in identifying ADHD is surprising given that the team used studies that directly measured executive functioning through neurocognitive tasks, excluding those that relied on parent- or teacher-reported questionnaires. 

67 studies involving 74 training interventions met the criteria. Meta-analysis of all these studies, encompassing a total of 3,101 participants, suggested medium-to-large effect size improvements in executive functioning. There was evidence of publication bias, but trim-and-fill adjustment increased the estimated effect size to large.

Nevertheless, there were further methodological shortcomings:

  • The meta-analysis mixed studies of substantially different interventions: cognitive training, executive function-specific curriculum, game-based training, neurofeedback, mindfulness, and physical exercise.
  • There was tremendous variation (heterogeneity) between study outcomes. Such inconsistency casts doubt on the outcome unless subgroup analysis can explain it. 

In this case, subgroup analysis mostly failed to explain the heterogeneity, with a single exception. Meta-analysis of the 16 studies with 744 participants that explored executive function-specific curriculum found small-to-medium effect size improvements, with no heterogeneity. 

Unfortunately, the team did not perform a separate publication bias analysis on this subgroup, just as it failed to do so on any of the other subgroups.

By far the strongest evidence of benefit came from meta-analysis of the 17 studies with 558 participants evaluating physical exercise. Here the outcome pointed to very large effect size improvements in executive functioning. Yet once again, heterogeneity was extremely high. Breaking this down further between aerobic exercise and cognitively engaged physical exercise made no difference. Both types had the same very high effect size, with very wide heterogeneity. Again, there was no separate evaluation of publication bias on this group.

Meta-analyses of thirteen studies of neurofeedback combining 444 participants, and fifteen studies of cognitive training encompassing 727 participants, both pointed to just-short-of-large effect size improvements in executive function. Meta-analysis of twelve studies of game-based training with 598 participants indicated medium effect size gains. But again, in all three subgroups there was great variation between studies, and no analysis of publication bias.

While these meta-analyses are suggestive of efficacy, especially for physical exercise interventions, their methodological shortcomings mean we will have to await more rigorous meta-analyses to draw any more settled conclusions. Moreover, these meta-analyses did not evaluate the adequacy of the control groups used in the trials, which is a big shortcoming given prior work showing that the effect of non-pharmacologic treatments are very weak or non-existent when adequate controls are used.

March 13, 2024

Untreated ADHD Nearly Doubles Risk of Motor Vehicle Crashes

Untreated ADHD nearly doubles risk of motor vehicle crashes, new meta-analysis finds

The Background:

Motor vehicle crashes remain one of the most significant public health challenges in the United States. In 2022 alone, nearly 44,000 people died on American roads, and more than 2.6 million crash-related injuries required emergency care. Most people are familiar with the usual suspects: drunk driving, speeding, and distracted driving from phones. These risks are well-documented and the focus of ongoing public safety campaigns. 

But a serious risk factor has been flying under the radar: untreated ADHD. Despite receiving little attention from the public, policymakers, or transportation safety agencies, it may belong in the same conversation as these better-known dangers. 

ADHD is not currently recognized by the National Highway Traffic Safety Administration as a driving risk factor; yet inattention and impulsivity, two of its defining features, are consistently cited as common contributors to crashes. Beyond these core symptoms, adults with ADHD may also experience emotional dysregulation, which can further impair driving behavior. 

The Research:

Prior studies on ADHD and crash risk have produced estimates ranging from a 5% to a 70% increase. This massive heterogeneity has made it difficult to draw firm conclusions. This new meta-analysis set out to offer some clarity on these numbers. 

Researchers focused specifically on adults aged 18 to 65 with a formal ADHD diagnosis who were not receiving treatment, comparing them to controls without ADHD. Four studies met these criteria, collectively covering more than 2.75 million people. 

The Results:

The findings were striking: untreated ADHD was associated with a 93% increase in crash risk (95% confidence interval: 88%–99%). There was no evidence of publication bias. Although there was meaningful variation across studies, most of it stemmed from the smallest study  (just 36 participants)  which reported an outlier estimate of a 16-fold increase. 

To put the 93% figure in context: a separate meta-analysis found that alcohol use is associated with a 150% increase in crash risk. Another way to understand just how significant this risk really is, untreated ADHD raises crash risk by more than half as much as alcohol does.

The analysis also found a dose-response relationship between ADHD symptom severity and crash risk: each incremental increase in symptom severity corresponded to a 5–6% higher crash risk. At the highest severity levels, crash risk approached that associated with alcohol use. This gradient reinforces that we're not looking at a binary distinction between “has ADHD” and “doesn’t” — the worse the symptoms, the greater the danger on the road. 

The Takeaway:

These findings have practical implications for patients, families, clinicians, and policymakers alike. Untreated ADHD is not a minor footnote in the driving safety literature; rather, it is a substantial, measurable, and potentially modifiable risk factor. The question of whether and how it should be factored into licensing policy, clinical practice, and public health messaging deserves serious attention. 

August 28, 2026

Childhood Exposure to Noise and Air Pollution and ADHD: A Meta-analysis

As populations grow, more children are growing up surrounded by traffic noise and polluted air.   In most cities, these two factors tend to go hand-in-hand; yet, most previous research has examined these exposures separately. Many reviews focused on a single pollutant (such as fine particulate matter, PM2.5), or on a single developmental window, such as pregnancy or early childhood. Few have asked how noise and air pollution compare as risk factors, or how prenatal and postnatal exposures differ in their effects. 

A new meta-analysis set out to address those gaps. It examined evidence on both environmental noise and several major air pollutants in relation to ADHD, compared exposures before versus after birth, and pooled data across countries and regions. Eligible studies involved children and adolescents under 18, used objective measures of environmental exposure, and assessed ADHD using either clinical diagnosis or standardized rating scales. 

Noise 

Nine studies, combining data from over 100,000 children and adolescents  (all in European countries and Canada) found that high noise exposure was associated with 3% greater odds of ADHD. Prenatal noise exposure showed no effect; childhood exposure alone drove the association, at 4% greater odds. This is a negligible effect size that could easily reflect unmeasured confounding factors rather than a true causal relationship. 

Nitrogen dioxide 

Thirteen studies covering nearly one million children and adolescents in Europe, Canada, China, and South Korea found that nitrogen dioxide (NO₂) exposure was associated with 11% greater odds of ADHD. As with noise, prenatal exposure showed no independent effect. When the analysis was restricted to the five studies that used clinical diagnoses alone — generally considered the most reliable measure — the estimated odds rose to between 20% and 80% higher. The wide range reflects substantial variation across studies. 

Pollutants with no significant effect 

Four studies (97,500 participants) examining nitric oxide (NO), three studies (over 63,000 participants) on ozone, and three studies (over 28,000 participants) on sulfur dioxide found no significant associations with ADHD. 

Particulate matter 

The strongest associations emerged for particulate matter. Twelve studies involving nearly 160,000 participants in China, the US, Canada, and Europe found that exposure to fine particles (PM2.5, 2.5 microns in diameter) was associated with 30% greater odds of ADHD. Ten studies covering more than a quarter of a million participants in India, China, South Korea, and Europe found that coarser particles (PM10, 10 microns) were associated with 50% greater odds. In both cases, prenatal exposure showed no association, which is consistent with the fact that fetuses do not breathe air through developed lungs. When restricted to clinically diagnosed ADHD, PM2.5 was associated with roughly 50% greater odds, and PM10 with more than double the odds. 

The Results

Across all exposures examined, particulate matter showed the clearest and strongest associations with ADHD, followed by nitrogen dioxide. Noise reached statistical significance but at a trivially small effect size. Nitric oxide, ozone, and sulfur dioxide showed no significant associations. 

The authors found no evidence of publication bias which strengthens confidence in the overall pattern. However, there was marked heterogeneity across individual studies: results varied considerably, which urges caution in treating any single estimate as definitive. These are associations, not proven causal relationships, and the possibility that unmeasured factors explain part of the signal cannot be ruled out.

New Expert Guidance on "Deprescribing" Stimulants for Adults with ADHD

The Background: 

Over the past two decades, diagnostic rates for adult ADHD have roughly doubled, and stimulant prescriptions in the United States skyrocketed by more than 50% between 2012 and 2023, particularly among girls and women. While these medications help many individuals manage their symptoms, a landmark 2026 article published in European Neuropsychopharmacology tackles an important question that is rarely discussed: When should doctors and patients consider stopping them?  

The Discussion: 

To answer this, the American Society of Clinical Psychopharmacology (ASCP) gathered a task force of 45 international experts spanning 12 countries. Through a rigorous evaluation process, they reached an overwhelming agreement on a framework for "deprescribing", the planned, supervised reduction or cessation of a medication. Here are the core insights from these ground-breaking guidelines and what they mean for adults navigating long-term ADHD treatment.  

When the Treatment Isn’t Yielding Benefits 

One of the most straightforward reasons to consider stopping a stimulant is if it simply isn’t doing its job. The task force agreed that if a patient does not experience an optimal response, measured by actual symptom reduction, improved daily functioning, and a better quality of life, even after trying a high, optimized dose, it may be time to step back and look at alternative options.  

Sometimes, the issue goes back to the initial evaluation. The criteria for diagnosing ADHD have expanded over the years, and brief psychiatric evaluations can occasionally lead to diagnostic inaccuracies. If a thorough reevaluation reveals that the original ADHD diagnosis was incorrect, the expert consensus is clear: stimulant deprescribing is appropriate unless another stimulant-responsive condition is evident. Furthermore, if a patient develops a persistent tolerance to the drug that cannot be resolved by safe dose adjustments, a temporary taper or drug holiday may be recommended.  

When the Risks to Health Outweigh the Rewards 

Our bodies and health needs naturally shift over time, meaning a medication that worked safely years ago might pose a threat to your health today. The experts concluded that deprescribing should be heavily considered if stimulants exacerbate a concurrent medical or psychiatric illness. For example, although rare, stimulants can unintentionally trigger mania or psychosis in adults with unstable or unrecognized comorbid bipolar disorder.  

Physical health developments are equally critical. If an adult develops a newly arising or unstable cardiovascular condition, such as a cardiac arrhythmia, ischemia, or cardiomyopathy, the risk-benefit balance changes dramatically. Additionally, if severe side effects occur that cannot be managed by reducing the dosage, or if dangerous new drug-drug interactions emerge, stopping the medication under medical supervision protects the patient's long-term well-being.  

Addressing Misuse and the Complex Role of Cannabis 

Because stimulant medications target brain reward and wakefulness circuitry, they can foster a propensity for misuse. Studies indicate that more than 1 in 5 adults prescribed stimulants have misused them, and 1 in 6 have diverted their medication to others. The task force emphasizes that deprescribing is warranted if a patient persistently takes doses higher than prescribed against medical advice, uses the medication purely for unauthorized performance enhancement, or has an untreated, coexisting substance use disorder.  

And what about cannabis? This topic sparked the most debate among the experts, falling just short of an official consensus with 71% agreement that regular cannabis use alone shouldn't automatically trigger a stimulant stoppage. Recognizing the complexity, such as how chronic cannabis use can overlap with ADHD executive function deficits, the task force proposed a structured monitoring approach instead of an immediate cutoff. Clinicians are encouraged to track the patient every 1 to 3 months using standardized symptom tools and random urine drug screens to verify whether cannabis use is actively neutralizing the stimulant's therapeutic benefits.  

The Path Forward: Safe Tapering and Lifestyle Support 

If you and your doctor decide that stopping a stimulant is the right path, it shouldn’t happen overnight. The task force strongly recommends that medications be gradually tapered off at a rate tailored to the individual to minimize potential disruptions and distinguish between transient withdrawal and a true return of ADHD symptoms.  

Crucially, stopping a medication doesn't mean stopping treatment. The experts highlight that the success of any deprescribing plan is significantly enhanced when patients focus on optimizing modifiable lifestyle factors. Prioritizing sleep hygiene, staying physically active, and implementing structured behavioral strategies can support executive functioning and help sustain your cognitive gains even as the medication is reduced or eliminated.  

The Takeaway: 

The decision to continue or stop an ADHD medication is a deeply personal one that requires balancing real-world efficacy, safety, and individual health changes. These new consensus recommendations provide an essential roadmap to help adults navigate their long-term mental health journeys safely and effectively.  

Are you or a loved one currently evaluating your long-term relationship with ADHD medication? Consider scheduling a check-in with your healthcare provider to discuss whether your current treatment plan still perfectly matches your health needs today.