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May 22, 2025
Background
A meta-analysis examined whether noninvasive brain stimulation (NIBS) techniques could help reduce core symptoms of ADHD and improve cognitive function. NIBS refers to techniques that stimulate brain activity using low electrical or magnetic currents applied from outside the head. They studied transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), while newer methods like tRNS (random noise) and tACS (alternating current) lacked enough studies to be included in the analysis.
Methods
Only randomized controlled trials (RCTs)—considered the gold standard in clinical research—were included in the review. For tDCS, the results were promising:
-A meta-analysis of 12 studies (582 participants) showed small but statistically significant improvements in inhibitory control (the ability to stop or delay responses).
-Nine studies (390 participants) showed small-to-medium improvements in working memory.
-Two smaller studies (94 participants) hinted at improvement in cognitive flexibility, but the results were not strong enough to be considered reliable.
-Seven studies (277 participants) found medium-to-large improvements in linattention, though results varied significantly between studies.
Hyperactivity and impulsivity showed some improvement, but again, the number of studies was too small to draw firm conclusions.
For rTMS, however, the results were not as encouraging. A meta-analysis of three studies (137 participants) found no significant improvement in ADHD symptoms.
Conclusion
While the results suggest that tDCS may offer some benefit for executive functions and attention in people with ADHD—especially when targeting specific brain areas like the F3/F4 regions (roughly over the dorsolateral prefrontal cortex)—the authors emphasize the need for further research. Most studies didn’t include long-term follow-up, and there’s still a lack of consistency in how stimulation is applied across studies. Moreover, even when positive findings emerged for executive functions is not clear how these translate into changes that are meaningful for the patient.
Importantly, this study doesn’t suggest that NIBS should replace standard treatments. Although the paper highlights challenges with medication adherence and side effects, ADHD medications and behavior therapies remain the most well-established and effective treatments for most patients. The improvements seen with NIBS so far are relatively small and preliminary in comparison.
Instead, the findings support the idea that NIBS could one day serve as a complementary tool—especially for individuals who don’t respond well to existing treatments. But until more rigorous and long-term studies are done, NIBS should be viewed as an experimental approach, not a substitute.
Yao Yin, Xueke Wang, and Tingyong Feng, “Noninvasive Brain Stimulation for Improving Cognitive Deficits and Clinical Symptoms in Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis,” Brain Sciences (2024), 14, 1237, https://doi.org/10.3390/brainsci14121237.
It sounds like science fiction, but scientists have been testing computerized methods to train the brains of ADHD people to reduce both ADHD symptoms and cognitive deficits such as difficulties with memory or attention.
Two main approaches have been used: cognitive training and neurofeedback. Cognitive training methods ask patients to practice tasks aimed at teaching specific skills, such as retaining information in memory or inhibiting impulsive responses.
Currently, results from ADHD brain studies suggest that the ADHD brain is not very different from the non-ADHD brain, but that ADHD leads to small differences in the structure, organization, and functioning of the brain. The idea behind cognitive training is that the brain can be reorganized to accomplish tasks through a structured learning process. Cognitive retraining helps people who have suffered brain damage, so it was logical to think it might help the types of brain differences seen in ADHD people. Several software packages have been created to deliver cognitive training sessions to ADHD people.
Neurofeedback was applied to ADHD after it had been observed, in many studies, that people with ADHD have unusual brain waves as measured by the electroencephalogram (EEG). We believe that these unusual brain waves are caused by the different ways that the ADHD brain processes information. Because these differences lead to problems with memory, attention, inhibiting responses, and other areas of cognition and behavior, it was believed that normalizing the brain waves might reduce ADHD symptoms.
In a neurofeedback session, patients sit with a computer that reads their brain waves via wires connected to their heads. The patient is asked to do a task on the computer that is known to produce a specific type of brain wave. The computer gives feedback via sound or a visual on the computer screen that tells the patient how 'normal' their brainwaves are. By modifying their behavior, patients learn to change their brain waves. The method is called neurofeedback because it gives patients direct feedback about how their brains are processing information.
Both cognitive training and neurofeedback have been extensively studied. If you've been reading my blogs about ADHD, you know that I play by the rules of evidence-based medicine. My view is that the only way to be sure that a treatment works is to see what researchers have published in scientific journals. The highest level of evidence is a meta-analysis of randomized controlled clinical trials. This ensures that many rigorous studies have been conducted and summarized with a sophisticated mathematical method.
Although both cognitive training and neurofeedback are rational methods based on good science, meta-analyses suggest that they do not help reduce ADHD symptoms. They may be helpful for specific problems, such as problems with memory, but more work is needed to be certain if that is true. The future may bring better news about these methods if they are modified and become more effective. You can learn more about non-pharmacologic treatment for ADHD from a book I recently edited: Faraone, S. V. &Antshel, K. M. (2014). ADHD: Non-Pharmacologic Interventions. Child Adolesc Psychiatr Clin N Am 23, xiii-xiv.
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:
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 ..."
A two-year study examined the effect of digital media use on ADHD symptoms in over 2500 adolescents. An earlier meta-analysis found that traditional media use (TV and video console games) was modestly associated with ADHD-like behaviors (Nikkelen et al 2014). The current study extends the examination to a large sample, with modern digital media delivery of high-intensity stimuli, including mobile platforms.
The authors used the Current Symptom Self-Report Scale (Barkley R 1998) to establish ADHD symptoms at baseline and six-month assessments over 24 months. None of the subjects reported having ADHD, study entry. Subjects were considered to be ADHD symptom-positive (the primary binary outcome) if they had greater than or equal to six inattentive and/or hyperactive-impulsive symptoms rated on this frequency-based scale (0-3). Modern digital media use was surveyed on a frequency basis for 14 media activities(including checking social media sites, texting, browsing, downloading or streaming music, posting pictures, online chatting, playing games, online shopping, and video chatting). The most common media activity was the high-frequency checking of social media. Of note, high-frequency engagement in each of the digital media activities was significantly, but moderately, associated with having ADHD symptoms at each six-month follow-up (OR 1.10), even after adjusting for covariates. High-frequency media use at baseline seemed to be associated with the development of ADHD symptoms.
Among the 495 students who reported no high-frequency media use at baseline, 4.6% met ADHD symptom criteria at follow-up. Among 114 students scoring 7 for high-frequency media use at baseline, 9.5% met the symptoms criteria. For the 51 students with a score of 14 for high-frequency media use at baseline, the rate was 10.5% (both comparisons were statistically significant).
This study is important in that it notes that an association between high-frequency digital media use (in current platforms and modalities) may be associated with the development of ADHD-like symptoms. A significant limitation of the study, as noted by the authors, is that ADHD-like symptoms do not establish a diagnosis of ADHD and do not assess impairment; therefore, these results must be interpreted with some caution. It does highlight that even with the current level of understanding, it might be prudent for clinicians to recommend limiting high-frequency media use for adolescent patients.
Stimulant medications, such as methylphenidate (Ritalin) and amphetamines (Adderall), are among the most widely prescribed drugs in the world. In the United States alone, prescription rates have climbed more than 50% over the past decade, driven largely by growing awareness of ADHD in both children and adults. Yet stimulants also have a long history of non-medical use, and concerns about their psychological risks persist among patients, families, and clinicians alike.
Two major studies now offer the clearest picture yet of what that risk actually looks like, and who it may affect.
The Background:
Before turning to the research, it helps to understand the landscape. A notable share of stimulant users misuse their medication: roughly one in four takes it in ways other than prescribed, and about one in eleven meets criteria for Prescription Stimulant Use Disorder (PSUD). Counterintuitively, most people with PSUD aren’t obtaining drugs illicitly — they’re misusing their own prescriptions.
This distinction between therapeutic and non-therapeutic use turns out to be critical when evaluating psychosis risk.
The Study:
A comprehensive meta-analysis by Jangra and colleagues pooled data across more than a dozen studies to compare psychotic outcomes in people using stimulants therapeutically versus non-therapeutically. The contrast was striking.
Among therapeutic users (more than 220,000 individuals taking stimulants at prescribed doses under medical supervision), psychotic episodes occurred in roughly one in five hundred people. When symptoms did appear, they typically emerged after prolonged treatment or in individuals with pre-existing psychiatric vulnerabilities, and they usually resolved when the medication was stopped.
Among non-therapeutic users (over 8,000 participants across twelve studies, many using methamphetamine or high-dose amphetamines), nearly one in three experienced psychotic symptoms. These episodes tended to be more severe, involving persecutory delusions and hallucinations, with faster onset and a greater likelihood of recurrence or persistence.
The biology underlying this difference is well understood. When stimulants are taken orally at guideline-recommended doses, they produce moderate, gradual changes in neurotransmitter activity central to attention and executive functions. The brain tolerates these changes relatively well. Non-therapeutic use, by contrast, often involves much higher doses that are frequently delivered through non-oral routes such as injection or smoking. This produces a rapid, excessive surge in dopamine activity, which is precisely the neurochemical pattern associated with psychotic symptoms.
The takeaway here is not that therapeutic stimulant use is risk-free, but that risk is strongly modulated by dose, route of administration, and individual psychiatric history. Clinicians are advised to monitor patients with pre-existing mood or psychotic disorders, particularly carefully.
A Nationwide Study Focuses on Methylphenidate Specifically:
Where the meta-analysis cast a wide net, a large-scale population study by Healy and colleagues drilled into a specific and clinically pressing question: does methylphenidate (the most commonly prescribed ADHD medication, also known as Ritalin) increase the risk of developing a psychotic disorder?
To find out, the researchers analyzed Finland's national health insurance database, tracking nearly 700,000 individuals diagnosed with ADHD. Finland's single-payer system made this kind of comprehensive, long-term tracking possible in a way that fragmented healthcare systems rarely allow.
Critically, the team adjusted for a range of confounding factors that have clouded previous research, including sex, parental education, parental history of psychosis, and the number of psychiatric visits and diagnoses prior to the ADHD diagnosis itself (a proxy for illness severity). After these adjustments, they found no significant difference in the risk of schizophrenia or non-affective psychosis between patients treated with methylphenidate and those who remained unmedicated. This held true even among patients with four or more years of continuous methylphenidate use.
The Take-Away:
When considered together, these studies offer meaningful reassurance without encouraging complacency.
For patients and families weighing ADHD treatment, the evidence suggests that methylphenidate used as prescribed does not increase psychosis risk, even over years of use. The rare cases of stimulant-associated psychosis in therapeutic settings are typically linked to high doses, pre-existing vulnerabilities, or both, and tend to resolve with discontinuation.
For clinicians, the findings reinforce the importance of baseline psychiatric assessment before initiating stimulant therapy, ongoing monitoring in patients with mood or psychotic disorder histories, and clear patient education about the risks of dose escalation or non-oral use.
The picture that emerges is one of a meaningful distinction between a medication used carefully within its therapeutic window and a drug misused outside of it. This distinction matters enormously when communicating risk to patients, policymakers, and the public.
ADHD is commonly treated with medication, but these treatments frequently cause side effects such as reduced appetite and disrupted sleep. Psychological and behavioral therapies exist as alternatives, but they tend to be expensive, hard to scale, and generally do little to address the motor difficulties that many children with ADHD experience — things like clumsy movement, poor handwriting, or difficulty with coordination.
Physical exercise has attracted attention as a more accessible option. But research findings have been mixed, partly because studies vary so widely in how exercise is delivered and what outcomes they measure. This meta-analysis, drawing on 21 studies involving 850 children and adolescents aged 5–20 with a clinical ADHD diagnosis, tries to cut through that noise.
Two types of motor skills
The researchers separated motor skills into two broad categories:
The Data:
Gross motor skills (16 studies, 613 participants)
Overall, exercise produced medium-to-large improvements in gross motor skills. The strongest gains were in:
No significant gains were found in balance or flexibility.
Fine motor skills (13 studies, 553 participants):
Exercise also produced medium-to-large improvements in fine motor skills, specifically:
The Results: What Kind of Exercise Works Best?
Two factors stood out consistently across both gross and fine motor skills: session length and frequency.
The type of exercise mattered; structured programs with clear motor-skill components (rather than unstructured physical activity) yielded stronger results.
These results are not without caveats, however. The authors urge caution in interpreting these findings. A few key limitations include:
The Bottom Line
This meta-analysis provides tentative moderate evidence that structured physical exercise can meaningfully support motor skill development in children and adolescents with ADHD — particularly when sessions run longer than 45 minutes and occur at least three times a week. The benefits appear most robust for object control, locomotion, handwriting, and manual dexterity.
That said, the evidence base still has real gaps. The authors call for better-designed, fully randomized controlled trials with consistent methods, standardized ways of measuring exercise intensity, and greater inclusion of children and adolescents who are not on medication — all of which would help clarify when, how, and for whom exercise works best.
Treatment guidelines for childhood ADHD recommend medications as the first-line treatment for most youth with ADHD. Still, concerns about side effects and long-term outcomes have increased interest in non-pharmacological approaches. Researchers at Saudi Arabian Armed Forces hospitals recently conducted a network meta-analysis comparing several interventions, including mindfulness-based therapy, cognitive behavioral therapy, behavioral parent training, neurofeedback, yoga, virtual reality programs, and digital working memory training.
Although the authors aimed to “provide a rigorous methodological approach to combine evidence from multiple treatment comparisons,” the study illustrates several pitfalls that arise when network meta-analysis is applied to a thin and heterogeneous evidence base.
What Network Meta-analysis Can and Cannot Do:
Network meta-analysis extends conventional meta-analysis by combining:
When the evidence network is large and well-connected, this approach can provide useful estimates of comparative effectiveness among many treatments.
This method is not always best, however, as many networks are sparse. This is especially true in areas such as complementary or behavioral therapies. In sparse networks, estimates rely heavily on indirect comparisons, and single studies can exert disproportionate influence over the results.
Conventional meta-analysis focuses on heterogeneity, meaning differences in results across studies within the same comparison.
Network meta-analysis must additionally evaluate consistency, whether the direct and indirect evidence agree.
However, when comparisons are supported by only one or two studies and the network is weakly connected, statistical tests for heterogeneity and consistency have very little power. In practice, this means the analysis often cannot detect problems even if they are present.
Sparse networks also make publication bias difficult to evaluate. This concern is particularly relevant in fields dominated by small trials and emerging therapies.
Why Such Treatment Rankings Are Appealing, but Potentially Problematic:
Many network meta-analyses summarize results using SUCRA, which estimates the probability that each treatment ranks best.
SUCRA, or Surface Under the Cumulative Ranking, is a key statistical metric in network meta-analyses. It is used to rank treatments by efficacy or safety. This is achieved by summarizing the probabilities of a treatment's rank into a single percentage, where a higher SUCRA value indicates a superior treatment. Ultimately, SUCRA helps pinpoint the most effective intervention among the ones compared.
Again, in well-supported networks, SUCRA can provide a useful summary of comparative effectiveness. But in sparse networks, rankings can create an illusion of precision, because treatments supported by a single small study may appear highly ranked simply due to random variation.
What Did this New Network Meta-analysis Study?
The study includes 16 trials with a total of 806 participants. But the structure of the evidence network is far weaker than this headline number suggests.
Based on the underlying studies:
This produces a very thin network, in which several interventions rely entirely on single studies.
Another challenge is that the included trials measure different outcomes. Some evaluate ADHD symptom severity, while others measure parental stress.
When studies use different outcome scales, meta-analysis typically relies on standardized measures such as the standardized mean difference to allow comparisons across studies. However, the analysis reports only mean-average differences, making it difficult to interpret the relative effect sizes.
Study Issues (including Limited Evidence and Risk of Bias):
The intervention supported by the largest number of studies (family mindfulness-based therapy) was one of the two approaches reported as producing statistically significant results. The other was BrainFit, which is supported by only a single previous trial.
Despite this limited evidence base, the study ranks interventions using SUCRA:
Notably, none of the runner-up interventions demonstrated statistically significant efficacy.
The authors acknowledge methodological limitations in the included studies:
“Blinding of participants and personnel (performance bias) exhibited notable concerns, as blinding for active treatment was not applicable in most studies.”
Such limitations are common in behavioral intervention trials, but they further increase uncertainty in already small evidence networks.
Conclusions:
The study ultimately concludes:
“This network meta-analysis supports MBT and BPT as effective non-pharmacological treatments for ADHD.”
However, the evidence underlying these claims is limited. Some analyses rely on very small numbers of studies and participants, and the network structure depends heavily on indirect comparisons.
Network meta-analysis can be a powerful tool when applied to a large, consistent, and well-connected body of evidence. When the evidence base is sparse, however, the resulting rankings and comparisons may appear statistically sophisticated while resting on a fragile evidentiary foundation.
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