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May 16, 2025

Seven New Meta-analyses Suggest Wide Range of Benefits from Exercise for Persons with ADHD

Seven New Meta-analyses Suggest Wide Range of Benefits from Exercise for Persons with ADHD

ADHD is associated with deficits in executive functions. These are mental processes that enable individuals to plan, focus attention, manage tasks, and regulate emotions. These skills encompass working memory, cognitive flexibility, and inhibitory control, which are crucial for goal-directed behavior and decision-making. 

Working memory, which temporarily stores and processes information, contributes to language development by helping individuals make sense of what they read or hear.  

Cognitive flexibility refers to the ability to change perspectives, adapt thinking strategies, adjust to changing needs and priorities, recognize errors, and grasp opportunities.  

Inhibition switching involves intentional control of attention and emotions, suppressing automatic responses when necessary to prevent inappropriate behavior.  

These elements are critical to academic, social, and professional success. 

An international study team (Li et al.) conducted a meta-analysis of randomized controlled trials (RCTs) to explore the efficacy of physical activity for improving executive functions among children with ADHD aged 6 to 12. 

Meta-analysis of eleven RCTs encompassing 388 children reported a medium-to-large effect size improvement in cognitive flexibility. However, it found no benefit from aerobic exercise (such as running, jumping). When limited to the nine studies with 301 children that focused on cognitively engaging exercise (such as soccer and water sports that require constant monitoring of other players and strategizing), it found a large effect size improvement. Correcting for possible publication bias had no effect on the outcome. 

Meta-analysis of nine RCTs totaling 398 children reported a large effect size improvement in working memory. Once again, it found no benefit from aerobic exercise. Focusing on the seven RCTs with 288 children that used cognitively engaging exercise, it found a very large effect size improvement. There was no sign of publication bias. 

Meta-analysis of fourteen RCTs combining 579 children reported a small-to-medium effect size improvement in inhibition switching. But whereas it found a medium effect size improvement for shorter interventions of less than an hour (eight RCTs, 334 children), it found no benefit from interventions lasting an hour or more (six RCTs, 245 children. Again, there was no sign of publication bias. 

The team concluded, “Our study shows that physical activity interventions have a positive effect on improving executive function in school-age children with ADHD, with cognitive-engaging exercises showing greater benefits across three executive function measures.” 

A Chinese study team (Yang et al.) performed a related meta-analysis on the effect of exercise on inhibitory control in adults. Combining eight RCTs with a total of 372 participants, it reported a very large effect size improvement in inhibitory control, primarily from regular exercise. However, the effects were heavily influenced by a couple of outliers. The team claimed to have performed a sensitivity analysis but offered no evidence. Likewise, they noted signs of publication bias but did not use the standard trim-and-fill analysis to correct for it. 

Another Chinese study team (Xiangqin Song et al.) examined the effect of exercise on working memory in children and adolescents.  

Meta-analysis of 17 RCTs encompassing 419 participants found a medium effect size improvement in working memory. The large effect size improvement for cognitive aerobic exercise (4 RCTs, 233 participants) was twice the effect size for simple aerobic exercise (8 RCTs, 397 participants), though this meta-analysis still found a small-to-medium effect size gain from the latter. There was no sign of publication bias.  

The team concluded, “The results indicate that cognitive-aerobic exercise and ball sports are significantly more effective than other types of exercise interventions in improving working memory. This difference may be attributed to the varying cognitive load, task complexity, and the degree of activation of executive functions across different exercise types. The findings suggest that when designing exercise interventions for children with ADHD, priority should be given to exercise types with higher cognitive load in order to more effectively enhance working memory.” 

A joint Australian-U.S. team (Singh et al.) conducted a meta-meta-analysis on the effect of exercise on executive functions, that is, a meta-analysis of previous meta-analyses of RCTs.  

Combining ten separate meta-analyses with well over 2,800 children and adolescents with ADHD, it reported large effect size improvements in executive functions overall. There was no further breakdown by type of executive function and type of physical activity.  

The team concluded, “While exercise was seen to have a moderate and similar positive impact across all populations with respect to general cognition and memory, benefits for executive function were particularly marked in individuals with ADHD. This subgroup was unique in demonstrating a large effect size. This could be attributed to the task selection and the fact that many ADHD studies involved children. While the exact reason for this finding is unclear, there is evidence to suggest that impairments in executive function are common among individuals with ADHD. As such, it is plausible that this population may have a greater capacity for improvement due to starting from a lower baseline, compared with those with ‘normal’ executive function.” 

Another Chinese study team (Yagang Song et al.) performed a meta-analysis of RCTs examining the effects of physical exercise on anxiety, depression, and emotion regulation among children and adolescents with ADHD.  

Meta-analysis of eleven studies with a combined total of 384 participants reported a medium effect size reduction in symptoms of anxiety, with a dose-effect response. Physical exercise once a week had no significant effect, while twice a week was associated with a medium effect size reduction, and three or more times a week with a very large effect size improvement. Moderate intensity exercise was three times more effective than low intensity exercise.  

Meta-analysis of seven studies encompassing 187 individuals similarly reported a medium effect size reduction in symptoms of depression. Once again, moderate intensity was far more effective than low intensity exercise. 

Meta-analysis of seven studies totaling 429 children and adolescents reported a very large effect size improvement in emotion regulation, especially for physical exercise conducted at least twice a week

There was no sign of publication bias in the anxiety, depression, or emotion regulation findings. 

The team concluded, “Physical exercise demonstrated a substantial overall impact on enhancing anxiety, depression, and emotional regulation in children with ADHD, exhibiting a dose-response effect correlated with the period, frequency, duration, and intensity of the exercise. This investigation ... presents an additional evidence-based therapeutic approach for the considerable number of children with ADHD who are not appropriate candidates for pharmacological intervention.” 

A joint U.S.-Hong Kong study team (Liu et al.) performed a meta-analysis exploring the effect of physical exercise on motor proficiency. Motor proficiency includes both gross motor skills (like walking and running) and fine motor skills (like writing and buttoning).  

Meta-analysis of ten studies encompassing 413 children and adolescents with ADHD reported a very large effect size improvement in motor proficiency from physical exercise. The gains for object control, fine manual control, and manual coordination were roughly twice the gains for body coordination. There was no sign of publication bias. 

Finally, a Spanish research team (González-Devesa et al.) conducted a meta-analysis examining the effect of exercise on objectively measured sleep status among persons with ADHD. 

Meta-analysis of three RCTs with a combined total of 131 individuals that used accelerometers to measure sleep duration reported no significant effect one way or the other from exercise

The team concluded, “The existing evidence regarding the use of exercise to manage sleep problems in individuals with ADHD remains inconclusive. Preliminary findings from this review suggest a potential positive effect of exercise on self-reported sleep quality; however, its efficacy in improving sleep duration could not be confirmed.” 

The Take-Away:

An ideal exercise regimen for children with ADHD should focus on cognitively engaging physical activities rather than simple aerobic exercise. Sports and activities that require strategic thinking, attention to others’ actions, and rapid decision-making—such as soccer, martial arts, or water-based team sports—gave the best results, especially for working memory and cognitive flexibility. These types of exercise also show strong benefits for emotional regulation, reducing anxiety and depression, and enhancing motor proficiency.

To maximize benefits, the regimen should include moderate-intensity sessions at least two to three times per week, each lasting less than an hour, as longer durations appear less effective for improving inhibitory control. This structured, cognitively demanding approach offers an evidence-based, non-pharmacologic treatment option for children with ADHD, particularly for those who cannot or prefer not to use medication.  We need, however, more work to determine if exercise will provide the same symptom reduction and protection from adverse outcomes as has been shown for medications.

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The Economic Burden of ADHD

The Economic Burden of ADHD

ADHD, especially when untreated, impairs patients and creates difficulties in families.  

Although these are the proximal targets of treatment, ADHD also burdens society due, for example, to underemployment and the use of health resources.   A recent study assessed the economic burden using the Danish population registries, researchers, which link medical information with employment, education, crime, and social care registers while maintaining confidentiality. They identified 5,269 adults with adult ADHD who had not been diagnosed with ADHD in childhood and, we can assume, were probably not treated for the disorder. They excluded patients with other psychiatric diagnoses and cases without a same-sex sibling free of any diagnosed psychiatric diagnoses. That left 460 pairs of same-sex siblings, one with an adult with ADHD and the other with no psychiatric diagnosis. They selected the non-ADHD sibling closest in age to the ADHD sibling. Using siblings mitigated the effects of genetics and upbringing between the ADHD group and normally developing controls.

Looking at personal income (combining work income and public transfers), adults with ADHD on average brought home about 12,000 Euros less - almost a third less - than their sibling counterparts. They also paid 40% less tax. Balancing that out, their after-tax income was roughly 7,500 Euros less than their siblings. With the additional personal cost of prescribed medication(prescriptions are relatively inexpensive in Denmark, and co-payments even more so) the net personal cost to adults with ADHD was 7,700 Euros.

The net public costs were considerably greater. That was primarily due to the reduction in taxes paid (about 4,500 Euros) and the increase in income replacement transfers (just over 5,500 Euros). The cost of additional crimes committed by adults with ADHD added another 1,000 Euros. Additional primary and secondary health care costs contributed another 1,000 Euros. Subsidies for prescribed medicines added 661 Euros, but that was partly counterbalanced by a reduction of 344 Euros in education costs. There were no significant differences in costs from traffic accidents or adult continuation of foster care. Overall, the net per capita public cost of adults with ADHD was just over 12,400 Euros each year.

Combining public and private costs, the per capita economic burden of adult ADHD was just over 20,000 Euros each year.

The study could not evaluate the extent to which ADHD treatment may reduce the economic burden, but given many studies that show treatment for ADHD reduces impairments, we would expect treatment to have a positive impact on the economic burden.  These results are extremely important for policymakers and for those who control the allocation of treatment in healthcare systems.  Although treating ADHD incurs costs, not treating it incurs even greater costs in the long run

May 5, 2023
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Driving, Safety, and ADHD

How to Improve Driving Safety for Teens and Adults With ADHD

Drivers with ADHD are far more likely to be involved in crashes, to be at fault in crashes, to be in severe crashes, and to be killed in crashes. The more severe the ADHD symptoms, the higher the risk. Moreover, ADHD is often accompanied by comorbid conditions such as oppositional-defiant disorder, depression, and anxiety that further increase the risk.

What can be done to reduce this risk? A group of experts has offered the following consensus recommendations:

·        Use stimulant medications. While there is no reliable evidence on whether-stimulant medications are of any benefit for driving, there is solid evidence that stimulant medications are effective in reducing risk. But there is also a “rebound effect” in many individuals after the medication wears off, in which performance becomes worse than it had been before medication. It is therefore important to time the taking of medication so that its period of effectiveness corresponds with driving times. If one has to drive right after waking up, it makes sense to take a rapid-acting form. The same holds for late-night driving that may require a quick boost.
·        Use a stick shift vehicle wherever possible. Stick shifts make drivers pay closer attention than automatic transmissions. The benefits of alertness are most notable in city traffic. But using a stick shift is far less beneficial in highway driving, where shifting is less frequent.
·        Avoid cruise control. Highways can be monotonous, making drivers more prone to boredom and distraction. That is even more true for those with ADHD, so it is best to keep cruise control turned off.
·        Avoid alcohol. Drinking and driving is a bad idea for everyone, but, once again, it’s even worse for those with ADHD. Parents should consider the no-questions-asked policy of either picking up their teenager anytime and anywhere or setting up an account with a ride-sharing service.
·        Place the smartphone out of reach and hearing. Cell phone use is as about as likely to impair as alcohol. Hands-free devices only reduce this risk moderately, because they continue to distract. Texting can be deadly. Sending a short text or emoticon can be the equivalent of driving 100 yards with one’s eyes closed. Either turn on Do Not Disturb mode or, for even greater effectiveness, place the smartphone in the trunk.
·        Make use of automotive performance monitors. These can keep track of maximum speeds and sudden acceleration and braking, to verify that a teenager is not engaging in risky behaviors.
·        Take advantage of “graduated driver’s licensing laws” wherever available. These laws forbid the presence of peers in the vehicle for the first several (for example, six) months of driving. Parents can extend that period for teenagers with ADHD, or set it as a condition in states that lack such laws.
·        Encourage practicing after obtaining a learner’s permit. Teenagers with ADHD generally require more practice than those without. A “pre-drive checklist” can be a good place to start. For example: check the gas, check the mirrors, make sure the view through the windows is unobstructed, put your cell phone in Do not disturb mode and place it out of reach, put on a seatbelt, and scan for obstacles.
·        Consider outsourcing. Look for a driving school with a professional to teach good driving skills and habits.

Experts do not agree on whether to delay licensing for those with ADHD. On the one hand, teenagers with ADHD are 3-4 years behind in the development of brain areas responsible for executive functions that help control impulses and better guide behavior. Delaying licensing can reduce risk by about 20 percent. On the other hand, teens with ADHD are more likely to drive without a license, and no one wants to encourage that, however inadvertently. Moreover, graduated driver’s licensing laws only have a legal effect on teens who get their licenses at the customary age.

August 13, 2021
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Can College Students Trying to Fake ADHD be Detected

Can College Students Trying to Fake ADHD be Detected

Many college students truly have ADHD and deserve to be treated, but some attempt to fake ADHD symptoms to get stimulant medications for nonmedical uses, such as studying and getting high.  Some students who fake ADHD also seek to gain accommodations that would give them additional time to complete exams. To address this issue, two psychologists examined data from 514 university students being assessed for ADHD to evaluate the ability of assessment tools to detect students who fake ADHD symptoms.

All participants had asked to be assessed to determine whether they could qualify for disability services. This was therefore by no means a random sample of university students, and could be expected to include some non-ADHD individuals seeking the benefits of an ADHD diagnosis. But this offered a good opportunity to explore which combination of tools would yield the best accuracy, and be best at excluding malingerers.

That was achieved by using both multiple informants and multiple assessment tools and comparing results. Self-assessment was supplemented by assessment by other informants (e.g. parent, partner, friend, or another relative). These were supplemented with symptom validity tests to check for telltale highly inconsistent symptom reporting, or symptom exaggeration, which could signal false positives.

On the other hand, some individuals with ADHD have executive functioning problems that may make it difficult for them to reliably appraise their symptoms on self-assessment tests, which can lead to false negatives. Performance validity tests were therefore also administered, to detect poor effort during evaluation, which could lead to false negatives.

Observer reporting was found to be more reliable than self-reporting, with significantly lower inconsistency scores (p < .001), and significantly higher exaggeration scores (p < .001). More than twice as many self-reports showed evidence of symptom exaggeration as did observer reports. This probably understates the problem when one considers that the observer reports were performed not by clinicians but by parents and partners who may themselves have had reasons to game the tests in favor of an ADHD diagnosis.

Even so, the authors noted, "External incentives such as procurement of a desired controlled substance or eligibility for the desired disability accommodation are likely to be of more perceived value to those who directly obtain them." They suggested compensating for this by making ADHD diagnoses only based on positive observer tests in addition to self-reports: "Applying an 'and' rule-one where both self-and observers reports were required to meet the diagnostic threshold-generally cut the proportions meeting various thresholds at least in half and washed out the differences between the adequate and inadequate symptom validity groups."

They also recommended including formal tests of response validity, using both symptom validity tests and performance validity tests. Overall, they found that just over half of the sub-sample of 410 students administered performance validity tests demonstrated either inadequate symptom or performance validity.

Finally, they recommended "that clinicians give considerable weight to direct, objective evidence of functional impairment when making decisions about the presence of ADHD in adults. The degree to which symptoms cause significant difficulty functioning in day-to-day life is a core element of the ADHD diagnostic criteria (American Psychiatric Association,2013), and it cannot be assumed that significant symptoms cause such difficulty, as symptoms are only moderately associated with such functional impairment. ... we urge clinicians to procure objective records (e.g., grade transcripts, work performance evaluations, disciplinary and legal records) to aid in determining functional impairment in adults assessed for ADHD."

August 9, 2021
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Liquid Medication Options for ADHD Adults with Autism Spectrum Disorder

Long-Acting Liquid Methylphenidate for Treating ADHD in Intellectually Capable Adults with Autism Spectrum Disorder

Treating ADHD With Methylphenidate in Adults With Autism

A team from Harvard Medical School and Massachusetts General Hospital conducted a six-week open-label trial of liquid-formulation extended-release methylphenidate (MPH-ER) to treat ADHD in adults with high-functioning autism spectrum disorder (HF-ASD). ASD is a lifelong disorder with deficits in social communication and interaction and restricted, repetitive behaviors. Roughly half of those diagnosed with ASD also are diagnosed with ADHD.

This was the first stimulant trial in adults with both ASD and ADHD. There were twelve males and three female participants, all with moderate to severe ADHD, and in their twenties, with IQ scores of at least 85.

The use of a liquid formulation enabled doses to be raised very gradually, starting with a daily dose of 5 mg(1mL) and titrating up to 60 mg over the first three weeks, then maintaining that level through the sixth week. Participants were reevaluated for ADHD symptoms every week during the six-week trial. The severity of ASD was assessed at the start, midpoint, and conclusion of the trial, as were other psychiatric symptoms.

Before the trial, researchers agreed on a combination of targets on two clinician-rated scoring systems that would have to be reached for treatment to be considered successful. One is a score of 2 or less on the CGI-S, a measure of illness severity, with scores ranging from 1 (normal, not at all ill) to 7 (most extremely ill). The other is a reduction of at least 30 percent in the AIS RS score, which combines each of 18 symptoms of ADHD on a severity grid (0=not present; 3=severe; overall minimum score: 0; overall maximum score: 54).

After the trial, twelve of the fifteen patients (80 percent) met the preset conditions for success. Fully fourteen (93 percent) saw a ≥ 30 percent reduction in their AISRS score, while twelve scored ≤ 2 on illness severity.

However, when using the patient-rated ASRS scoring system, only five (33 percent) saw a ≥ 30 percent reduction in ADHD severity.

Thirteen participants (87percent) reported at least one adverse event, and nine (60 percent) reported two or more. One reported a serious adverse event (attempted suicide) in a patient with multiple prior attempts. Because the attempt was not deemed due to medication, they continued and completed the trial. Seven participants experienced titration-limiting adverse events (headaches, palpitations, jaw pain, and insomnia). Headache was most frequent (53%), followed by insomnia and anxiety(33% each), and decreased appetite (27%).

During the trial, weight significantly decreased, while pulse significantly increased. There were no significant differences in other vital and cardiovascular measurements.

The authors concluded, "this OLT of short-term MPH-ER therapy documents that acute treatment with MPH-ER in young adults with ASD was associated with significant improvement in ADHD symptoms, mirroring the typically-expected magnitude of response observed in adults with only ADHD. Treatment with MPH-ER was well-tolerated, though associated with a higher than expected frequency of adverse events."

They also cautioned, "The results of this study need to be considered in light of some methodological limitations. This was an open-label study; therefore, assessments were not blind to treatment. We did not employ a placebo control group and, therefore, cannot separate the effects of treatment from time or placebo effects. ... firmer conclusions regarding the safety and efficacy of MPH-ER for the treatment of ADHD in HF-ASD populations await results from larger, randomized, placebo-controlled clinical trials."

August 7, 2021
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How to Identify ADHD in Adults With Alcohol Use Disorder (AUD)

How to identify ADHD in adults with alcohol use disorder (AUD)

ADHD is far more prevalent among persons with AUD (roughly20 percent) than it is in the general population. The most accurate way of identifying ADHD is through structured clinical interviews. Given that this is not feasible in routine clinical settings, ADHD self-report scales offer a less reliable but much less resource-intensive alternative. Could the latter be calibrated in a way that would yield diagnoses that better correspond with the former?

A German team compared the outcomes of both methods on 404 adults undergoing residential treatment for AUD. All were abstinent while undergoing evaluations. First, to obtain reliable ADHD diagnoses, each underwent the Diagnostic Interview for ADHD in Adults, DIVA. If DIVA indicated probable ADHD, two expert clinicians conducted successive follow-up interviews. ADHD was only diagnosed when both experts concurred with the DIVA outcome.

Participants were then asked to use two adult ADHD self-report scales, the six-item Adult ADHD Self Report Scale v1.1 (ASRS) and the 30-item Conner's Adult ADHD Rating Scale (CAARS-S-SR). The outcomes were then compared with the expert interview diagnoses.

Using established cut-off values for the ASRS, less than two-thirds of patients known to have ADHD were scored as having ADHD by the test. In other words, there was a very high rate of false negatives. Lowering the cut-off to a sum score ≥ 11 resulted in an incorrect diagnosis of more than seven out of eight. But the rate of false positives shared to almost two in five. Similarly, the CAARS-S-SR had its greatest sensitivity (ability to accurately identify those with ADHD) at the lowest threshold of ≥ 60, but at a similarly high cost in false positives (more than a third).

The authors found it was impossible to come anywhere near the precision of the expert clinical interviews. Nevertheless, they judged the best compromise to be to use the lowest thresholds on both tests and then require positive determinations from both. That led to successfully diagnosing more than three out of four individuals known to have ADHD, with a false positive rate of just over one in five.

Using this combination of the two self-reporting questionnaires with lower thresholds, they suggest, could substantially reduce the under-diagnosis of ADHD in alcohol-dependent patients.

August 5, 2021
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Pharmacotherapy and ADHD in Adults with Autism Spectrum Disorder

How effective is pharmacotherapy of ADHD in adults with Autism Spectrum Disorder?

Autism spectrum disorder (ASD) is frequently comorbid with ADHD. Among adults with ADHD, as many as half are reported to also have ASD.

A Dutch team set out to answer two questions:


1)    Do adults with ADHD and comorbid ASD experience less effectiveness in pharmacological treatment for ADHD than adults with only ADHD
2)    Do adults with ADHD and comorbid ASD experience different or more severe side effects of pharmacological treatment for ADHD than adults with only ADHD, as measured in side effect scores, blood pressure, heart rate, and weight?

This was a retrospective study, using well-documented medical records, of the effects of drug treatment with methylphenidate (MPH), dexamphetamine (DEX), atomoxetine (ATX), bupropion, or modafinil.

The researchers compared 60 adults with comorbid ASD and ADHD to 226 adults with only ADHD. ADHD symptoms were scored using the Conner's ADHD Rating Scale: Self Report-Short Version (CAA RS: S-S). Side effects of ADHD medication were measured using either a 13-item or 20-item checklist with 4-point scales for item response. Researchers also tracked changes in body weight, blood pressure, and heart rate.

Following treatment, ADHD symptoms among the comorbid group declined by a quarter, and among the ADHD-only group by almost a third. There was no significant difference between men and women. Controlling for age, gender, and ADHD subtype, a comorbid diagnosis of ASD also did not significantly affect ADHD symptom reduction.

Turning to side effects, in the ADHD+ASD group, there were significant increases in decreased appetite and weight loss, and decreases in agitation, anxiety, and sadness/unhappiness. In the ADHD-only group, there were significant increases in decreased appetite, weight loss, and dry mouth, and decreases in sleeping disorder, nervousness, agitation, anxiety, and sadness/unhappiness. Yet there were no significant differences between the two groups. Side effects increased and decreased similarly in both. Likewise, there were no significant differences between the groups in changes in heart rate and blood pressure. The only significant difference in medication dosage was for bupropion, which was higher in the ADHD+ASD group, though without any sign of the difference in side effects.

The authors concluded that this retrospective study "showed pharmacological treatment of adults with diagnoses of ADHD and ASD to be just as successful as the pharmacological treatment of adults with only ADHD," but cautioned that "randomized controlled trial should be conducted to evaluate the effectiveness and possible side effects of pharmacological treatment for ADHD in patients with ASD more reliably."

August 3, 2021
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New Insights Into The Brains of People Living with ADHD and ADHD Symptoms

New insights into the brains of people living with ADHD and those with ADHD symptoms.

In this study, researchers found subtle differences in the cortex of the brains of children with ADHD.

The ENIGMA-ADHD Working Group published a second large study on the brains of people with ADHD in the American Journal of Psychiatry this month. In this second study, the focus was on the cerebral cortex, which is the outer layer of the brain.

 ADHD symptoms include inattention and/or hyperactivity and acting impulsively. The disorder affects more than one in twenty (5.3%) children, and two-thirds of those diagnosed continue to experience symptoms as adults.
In this study, researchers found subtle differences in the brain's cortex when they combined brain imaging data on almost 4,000 participants from 37 research groups worldwide. The differences were only significant for children and did not hold for adolescents or adults. The childhood effects were most prominent and widespread for the surface area of the cortex. More focal changes were found in the thickness of the cortex. All differences were subtle and detected only at a group level, and thus these brain images cannot be used to diagnose ADHD or guide its treatment.


These subtle differences in the brain's cortex were not limited to people with the clinical diagnosis of ADHD: they were also present - in a less marked form - in youth with some ADHD symptoms. This second finding results from a collaboration between the ENIGMA-ADHD Working Group and the Generation Study from Rotterdam, which has brain images of, 2700 children aged 9-11 years from the general population. The researchers found more symptoms of inattention to be associated with a decrease in cortical surface area. Furthermore, siblings of those with ADHD showed changes to their cortical surface area that resembled their affected sibling. This suggests that familial factors such as genetics or shared environment may play a role in brain cortical characteristics.


This is the largest study to date to look at the cortex of people with ADHD. It included 2246 people with a diagnosis of ADHD and 1713 people without, aged between 4 and 63 years old. This is the second study published by the ENIGMA-ADHD Working Group; the first examined structures that are deep in the brain. The ADHD Working Group is one of over 50 working groups of the ENIGMA Consortium, in which international researchers pull together to understand the brain alterations associated with different disorders and the role of genetic and environmental factors in those alterations.


The authors say the findings could help improve understanding of the disorder. 'We identify cortical differences that are consistently associated with ADHD, by combining data from many research groups internationally. We find that the differences extend beyond narrowly-defined clinical diagnoses and are seen, in a less marked manner, in those with some ADHD symptoms and unaffected siblings of people with ADHD. This finding supports the idea that the symptoms underlying ADHD may be a continuous trait in the population, which has already been reported by other behavioral and genetic studies.'. In the future, the ADHD Working Group hopes to look at additional key features in the brain - such as the structural connections between brain areas - and to increase the representation of adults affected by ADHD, on whom limited research has been performed to date.

August 1, 2021
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Are Low Vitamin D Levels a Risk Factor for ADHD?

Are low Vitamin D levels a risk factor for ADHD?

A team of Iranian researchers recently published a meta-analysis seeking to determine what, if any, association there may be between low vitamin D levels and ADHD in children and adolescents.
Combining the results from thirteen studies with 10,334participants, they found that youth with ADHD had "modest but significant" lower serum concentrations of 25-hydroxyvitamin D than normally developing children. The weighted mean difference was just under 7 nanograms per milliliter. The odds of obtaining such a result by chance would be less than one in a thousand(p < .001). There was little to no sign of publication bias. Between-study heterogeneity, however, was very high (I2 = 94).
These results suggest an association. But are low serum levels of vitamin D a cause or effect of ADHD? Causation is vastly more difficult to establish than an association. To begin to tease this out, the researchers identified four prospective studies that compared maternal vitamin D levels with the subsequent development of ADHD symptoms in their children. Two of these used maternal serum levels, and two used umbilical cord serum levels. Together, these studies found that low maternal vitamin D levels were associated with a 40% higher risk of ADHD in their children. Whether maternal serum or umbilical cord serum measurements were used had little or no effect on the outcome. Study heterogeneity was negligible. But the authors noted that this result "should be considered with caution" because it was heavily dependent on one of the prospective studies included in the analysis. All of which suggest a need for further prospective studies
In the meantime, the authors suggest it would be prudent to increase sun exposure and vitamin D supplementation, given the prevalence of vitamin D deficiency.

July 30, 2021
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Is there a relationship between ADHD and Internet Gaming Disorder?

Is there a relationship between ADHD and Internet Gaming Disorder?

A Spanish team of researchers recently completed a comprehensive review of studies looking for links between compulsive video gaming (both online and offline) and a variety of psychological disorders, including anxiety, depression, social phobia, and ADHD. The focus was on behavior "of sufficient severity to result in significant impairment in personal, family, social, educational, occupational or other important areas of functioning."

The team identified 24 studies, of which eight with a combined total of 16,786 participants looked for associations with either ADHD or its hyperactivity component. Participants included children, adolescents, and adults. One large longitudinal study, with 3,034 participants, found no association. Another study with 1,095 participants found a small effect. Two more, with a combined total of 11,868 found medium effect sizes. Four studies found large associations, but their combined total number of participants, was789, comprising less than a twentieth of the combined participants.

The authors concluded, "The relationship between Internet Gaming Disorder and ADHD and hyperactivity symptoms were analyzed in eight studies. Seven of them reported full association, with four finding large, two finding small, and one reporting moderate, effect sizes. The studies comprised two case-control, five cross-sectional and one longitudinal design; they later found no association between the two variables."[1]They also emphasized that 87 percent "of the studies describe significant correlations ... with ADHD or hyperactivity symptoms."[2]

Yet they did not note that all the studies with large effect sizes were comparatively small. And while they presented funnel charts evaluating publication bias for anxiety and depression, they did not do so for ADHD, where the small studies with very large effect sizes suggest publication bias (i.e., that evidence for association is exaggerated due to the early publication of positive findings).

Leaving out these small studies, the four high-powered studies with 15,997 participants reported effect sizes ranging from none to medium. Overall, that suggests that there is an association between ADHD and video gaming, though not a particularly strong one.  Moreover, due to the nature of the study designs, this work cannot conclude that the small effect observed is due to playing video games being a risk factor for ADHD or to the possibility that ADHD youth are more attracted to video games than others.

July 28, 2021
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Social and Self-Stigmatization in Adults with ADHD

Social and Self-Stigmatization in Adults with ADHD

A German team recruited 104 adults with ADHD at both inpatient and outpatient ADHD clinics, and from ADHD self-help groups. Just under two-thirds were being treated with ADHD drugs, most with methylphenidate.


Just under a quarter reported high internalized stigma. Two in five reported high levels of alienation, meaning a sense of "not being a fully functioning, valuable member of society." Three in ten reported high levels of social withdrawal.


On the other hand, only two participants reported high levels of stereotype endorsement, meaning personal acceptance of stereotypes associated with mental illness. And more than two-thirds reported high stigma resistance, meaning they were internally resistant to stigmatization. Thus, while most were free of significant internalized stigma, a still substantial minority were not.


Most of the participants expected to be discriminated against and treated unfairly by employers, colleagues at work, neighbors, and teachers should they reveal that they have ADHD. Relatively few expected to be discriminated against by health professionals, family, and friends. Almost half expected discrimination if they confided to strangers they were dating.


Over two-thirds of participants reported they had encountered public stereotypes concerning ADHD. But, on balance, they rated these at low levels of intensity. Nevertheless, among those perceiving such stereotypes, eight out of nine sensed some degree of public doubt about the validity of ADHD as a genuine ailment ("ADHD does not exist in adults"), and three out of four had at some point encountered the argument that "ADHD is invented by drug companies." More than four out of five had heard allegations that ADHD results from bad parenting, and almost three in four had heard the claim that it results from watching too much television or playing too many video games.


These data call for more education of the public about the nature and causes of ADHD. Information reduces stigmatization, so the widespread dissemination of the facts about ADHD is warranted.

April 8, 2024
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