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October 31, 2025
Background:
Pharmacotherapies, such as methylphenidate, are highly effective for short-term ADHD management, but issues remain with medication tolerability and adherence. Some patients experience unwanted side effects from stimulant medications, leaving them searching for alternative ADHD treatments. Alternative treatments such as cognitive training, behavioral therapies, psychological interventions, neurofeedback, and dietary changes have, so far, shown limited success. Thus, there is a critical need for non-pharmacological options that boost neurocognitive performance and address core ADHD symptoms.
First— What Are NIBS (Non-Invasive Brain Stimulation) Techniques?
Non-invasive brain stimulation (NIBS) techniques, including transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), transcranial alternating current stimulation (tACS), and repetitive transcranial magnetic stimulation (rTMS) are generating growing attention within the scientific community.
NIBS techniques are methods that use external stimulation, such as magnets or electrical currents, to affect brain activity without any invasive procedures. In transcranial alternating current stimulation (tACS), for example, small electrodes are placed on the scalp of the patient, and a weak electrical current is administered.
The theory behind these techniques is that when a direct current is applied between two or more electrodes placed on specific areas of the head, it makes certain neurons more or less likely to fire. This technique has been successfully used to treat conditions like depression and anxiety, and to aid recovery from stroke or brain injury.
The Study:
Previous meta-analyses have produced conflicting indications of efficacy. A Chinese research team consisting of sports and rehabilitative medicine professionals has just published a network meta-analysis to explore this further, through direct comparison of five critical outcome domains: inhibitory control, working memory, cognitive flexibility, inattention, hyperactivity and impulsivity.
To be included, randomized controlled trials needed to have participants diagnosed with ADHD, use sham control groups, and assess ADHD symptoms and executive functions – such as inhibitory control, working memory, cognitive flexibility, inattention, hyperactivity, and impulsivity – using standardized tests.
A total of thirty-seven studies encompassing 1,615 participants satisfied the inclusion criteria. It is worth noting, however, that the authors did not specify the number of randomized controlled trials nor the number of participants included in each arm of the network meta-analysis.
Furthermore, the team stated, “We checked for potential small study effects and publication bias by conducting comparison-adjusted funnel plots,” but did not share their findings. They also did not provide information on outcome variation (heterogeneity) among the RCTs.
Results:
Ultimately, none of the interventions produced significant improvements in ADHD symptoms, whether in inattention symptoms or hyperactivity/impulsivity symptoms. Likewise, none of the interventions produced significant improvements in inhibitory control. Some tDCS interventions enhanced working memory and cognitive flexibility, but details about trial numbers and participants were missing. The team concluded, “none of the NIBS interventions significantly improved inhibitory control compared to sham controls. … In terms of working memory, anodal tDCS over the left DLPFC plus cathodal tDCS over the right DLPFC … and anodal tDCS over the right inferior frontal cortex (rIFC) plus cathodal tDCS over the right supraorbital area ... were associated with significant improvements compared to sham stimulation. For cognitive flexibility, only anodal tDCS over the left DLPFC plus cathodal tDCS over the right supraorbital area demonstrated a statistically significant benefit relative to sham. ... Compared to the sham controls, none of the NIBS interventions significantly improved inattention. ... Compared to the sham controls, none of the NIBS interventions significantly improved hyperactivity and impulsivity.”
How Should We Interpret These Results?
In a word, skeptically.
If one were to read just the study’s abstract, which states, “The dual-tDCS and a-tDCS may be considered among the preferred NIBS interventions for improving cognitive function in ADHD”, it might seem that the takeaway from this study is that this combination of brain stimulation techniques might be a viable treatment option for those with ADHD. Upon closer inspection, however, the results do not suggest that any of these methods significantly improve ADHD symptoms. Additionally, this study suffers from quite a few methodological flaws, so any results should be viewed critically.
Xinwen Liang, Xiaoyu Wei, Yan Huang, Jing Li, Huan Feng, Jingyuan Fan, Longguo Zhang,
Zhijiang Wang, Xin Zhao, Weimin Pan, and Rui Liu, “Comparative efficacy of non-invasive
brain stimulation for attention-deficit/hyperactivity disorder: a systematic review and network
meta-analysis,” Frontiers in Neurology (2025), https://doi.org/10.3389/fneur.2025.1650154
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 ..."
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.
Noting that "despite a lack of solid evidence for their use, rTMS [repetitive transcranial magnetic stimulation]and tDCS [transcranial direct current stimulation] are already offered clinically and commercially in ADHD," and that a recent meta-analysis of ten tDCS studies found small but significant improvements in outcomes, but had several methodological shortcomings and did not include two studies reporting mostly null effects, a team of British neurologists performed a meta-analysis of all twelve sham-controlled, non-open-label, studies found in a comprehensive search of the peer-reviewed literature.
Ten of the twelve randomized-controlled trials used anodal stimulation of the dorsolateral prefrontal cortex, while the other two used anodal stimulation of the right inferior frontal cortex.
The trials explored several measures of cognition. The research team carried out a meta-analysis of all twelve trials, with a total of 232 participants, and found no significant improvement in attention scores from CDC, relative to sham stimulation. A second meta-analysis, of eleven trials with a total of 220 participants, assessed the efficacy of tDCS on improving inhibition scores, and again found no significant effect. A third meta-analysis, encompassing eight trials with a total of 124 participants, evaluated the efficacy of tDCS on improving processing speed scores, once again finding no significant effect.
The latter two meta-analyses approached the border of significance, prompting the authors to speculate that larger sample sizes could bring the results just over the threshold of significance. Even so, effect sizes would be small.
It is also possible that the trials focused on regions of the brain suboptimal for this objective, and thus the authors "cannot rule out the possibility that stimulation of other prefrontal regions (such as the right hemispheric inferior frontal cortex or dorsolateral prefrontal cortex or parietal regions), multiple session tDCS or tDCS in combination with cognitive training could improve clinically or cognitive functions in ADHD."
As to concerns about safety, on the other hand, "stimulation was well-tolerated overall."
The authors concluded that based on current evidence, tDCS of the dorsolateral prefrontal cortex cannot yet be recommended as an alternative Neurotherapy for ADHD.
Background:
Traditional measures of obesity, like body mass index (BMI) and waist circumference, have been linked to ADHD risk — but they aren’t great at capturing where fat is actually stored in the body. A newer index called relative fat mass (RFM), which combines height and waist circumference, does a better job of estimating overall body fat and predicting metabolic risks like heart disease and metabolic syndrome. Because those conditions share some underlying biological mechanisms with ADHD, researchers wondered whether RFM might also help explain the relationship between obesity and ADHD — particularly in children.
That question is complicated by the fact that ADHD doesn't look the same in boys and girls. Boys tend to display more hyperactive and impulsive behavior, making their ADHD easier to spot. Girls more often show inattention, which is quieter and frequently goes undiagnosed.
The Study:
A new study set out to test whether RFM is associated with ADHD in children, and whether that association differs between sexes. Using data from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2004, the researchers narrowed a large initial pool of over 31,000 participants down to 5,089 children and adolescents aged 6 to 14 who had complete data on height, waist circumference, ADHD screening, and other relevant variables.
After adjusting for age, race/ethnicity, Poverty-Income Ratio, maternal age at delivery, maternal smoking during pregnancy, health insurance coverage, and birth weight, the results revealed a striking split along sex lines.
In boys, higher RFM was associated with lower odds of ADHD. Compared to boys in the lowest fat-mass quartile, those in the second quartile had about 10% lower odds of ADHD, rising to over 30% lower in the third quartile and nearly 40% lower in the highest. In girls, the pattern reversed entirely. While girls in the second quartile showed similar odds to those with the lowest RFM, girls in the third and fourth quartiles had 60% to 70% greater odds of ADHD.
Conclusion & Why This Matters:
In recent years, the relationship between obesity and ADHD has become an increasingly important focus in pediatric neurodevelopmental research. Studies have reported higher rates of ADHD symptoms among children and adolescents with obesity compared with their non-obese peers, and difficulties with peer relationships have also been linked to increased obesity risk (Sönmez et al., 2019). From a neurobiological standpoint, both conditions may involve shared underlying mechanisms, particularly dysfunction in dopaminergic pathways.
The authors concluded that higher body fat levels appear to lower ADHD risk in boys while raising it in girls. This finding highlights why sex-specific analysis matters in ADHD research. The underlying biological reasons for this divergence, however, remain an open question and open the door for future research.
While ADHD is a developmental disorder, shaped by biology and genetics, growing evidence shows that it is also influenced by the social and environmental conditions in which children grow up. Research on the social determinants of health emphasizes that development is shaped not only by biology but also by factors such as family income, access to healthcare, neighborhood safety, and material stability. These factors can affect both how developmental challenges appear and whether they are recognized and diagnosed.
Children facing socioeconomic disadvantage consistently show higher risks of developmental and behavioral difficulties. Chronic stress linked to poverty – including financial strain, food insecurity, and limited access to resources – has been associated with problems in attention, emotional regulation, and daily functioning. Children from lower-income families also tend to experience more severe ADHD symptoms and face greater barriers to ongoing care.
Neighborhood conditions matter as well. Unsafe environments can limit opportunities for play and social interaction while increasing caregiver stress, all of which may influence children’s behavior and development. Material hardships, such as food insecurity, can further undermine stability at home.
The Study:
The study analyzed six years of data from the National Survey of Children’s Health (2018–2023), covering more than 205,000 U.S. children aged 3 to 17. After accounting for age, sex, race and ethnicity, region, family structure, survey year, and other social factors, the researchers found a strong income gradient in ADHD prevalence. Compared with children in households earning at least four times the federal poverty level, those in households earning two to four times that level had 28 percent higher odds of ADHD. Odds rose to 70 percent higher in households earning one to two times the poverty level, and more than doubled among children living below the poverty line.
Parental education showed a similar pattern. Compared with children whose parents had completed college, ADHD odds were 20 percent higher among those whose parents had some college education, 40 percent higher among those whose parents had only a high school education, and 80 percent higher among those whose parents had not finished high school.
Children living in unsafe neighborhoods had nearly twice the odds of ADHD compared with those in safe neighborhoods, and food insecurity was also linked to almost double the odds.
By contrast, race and ethnicity alone were associated with much smaller differences. Compared with non-Hispanic White children, children in non-Hispanic Black households had an 18 percent higher likelihood of ADHD, while children in Hispanic households had a 25 percent lower likelihood. No substantial differences were observed for children from other or multiracial households.
Conclusion and Takeaway:
The study team concluded, “Children living in lower-income households, experiencing food insecurity, and residing in unsafe neighborhoods consistently showed higher prevalence and higher adjusted odds of both conditions. … Overall, these findings reinforce the need to view neurodevelopmental disorders within a broader social and structural framework.”
It should be noted that this study is not aiming to name social factors as direct causes of ADHD. Rather, it points to socioeconomic disparities as contributing to the way ADHD develops and how it is treated. This type of research, as well as acknowledging barriers to care, is crucial for clinicians, counselors, teachers, etc., to consider when working with youth with ADHD.
Counting umbilical cord vessels is standard in prenatal ultrasounds and confirmed at birth. Single umbilical artery (SUA) occurs in about 1 in 200 cases, with roughly 10% associated with anomalies, including central nervous system defects. Isolated SUA (iSUA) means one artery is missing without other structural issues.
Research on SUA, especially isolated iSUA, and childhood neurodevelopmental disorders (NDD) is limited and inconclusive. iSUA is linked to preterm birth and small-for-gestational age (SGA), both of which are NDD risk factors.
This Norwegian nationwide population study aimed to assess NDD risk in children with iSUA at birth, the influence of sex, and how preterm birth and SGA mediate this relationship.
The nation’s universal single-payer health insurance and comprehensive population registries made it possible to analyze all 858,397 single births occurring from 1999 to 2013, with follow-up continuing through 2019. Among these cases, 3,532 involved iSUA.
After adjusting for confounders such as parental age, education, and maternal health factors, no overall link was found between iSUA and later ADHD diagnosis. However, females with iSUA had about a 40% higher risk of subsequent ADHD compared to those without iSUA, even after adjustment.
The authors concluded, “The present study indicates that iSUA is weakly associated with ID [intellectual disability] and ADHD, and these associations are influenced by sex. This association is mediated negligibly through preterm birth and SGA. The associations were not clinically significant, and the absence of associations of iSUA with other NDD is reassuring. This finding can be useful in the counseling of expectant parents of fetuses diagnosed with iSUA.”
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