June 4, 2024

Understanding the Role of Disinhibition in ADHD and the Impact of Physical Activity

ADHD often includes a problem called disinhibition. This means that the brain struggles to control attention, thoughts, emotions, and behavior, which can lead to negative outcomes. Normally, inhibition helps people stay focused and avoid distractions, but when it fails, it's called disinhibition.

Children with ADHD who have problems with inhibition may face issues like substance abuse, self-harm, and antisocial behavior. Improving their inhibition can help them better manage themselves, do well in school, and have better relationships.

A team of researchers from China and South Korea explored whether physical activity could improve inhibition in children with ADHD. They reviewed studies and excluded those without control groups, those with poor quality assessments, and those involving other interventions like cognitive training or supplements. Their final analysis included 11 studies with 713 participants.

Key Findings on Physical Activity

  1. Frequency and Duration: Physical activity had to be done at least twice a week to show significant improvement in inhibition. Sessions needed to last between 45 minutes to an hour for noticeable benefits, with sessions over an hour showing even greater improvements.
  2. Consistency: Regular, long-term physical activity was more effective than single sessions.
  3. Intensity: Moderate-to-vigorous activities were better than moderate activities alone.
  4. Type of Activity:some text
    • Open-skilled sports (like ping-pong or taekwondo) which involve reacting to changing environments, showed the most significant improvements.
    • Closed-skill sports (like running or swimming) showed smaller improvements.
    • Exergaming (exercise using video games) had moderate benefits.
  5. Specific Improvements:some text
    • Improvements in response inhibition (the ability to control impulsive responses) were small to medium.
    • Improvements in interference suppression (preventing distractions from affecting working memory) were large.

Conclusion

The research concluded that physical activity can significantly improve the inhibition in children with ADHD, especially with regular, moderate-to-vigorous, open-skilled exercise done at least twice a week for an hour or more. Future studies should continue to explore this with high-quality methods to confirm these findings.

Meng Wang, Xinyue Yang, Jing Yu, Jian Zhu, Hyun-Duck Kim, and Angelita Cruz, “Effects of Physical Activity on Inhibitory Function in Children with Attention Deficit Hyperactivity Disorder: A Systematic Review and Meta-Analysis,” International Journal of Environmental Research and Public Health (2023) 20, 1032, https://doi.org/10.3390/ijerph20021032.

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Immediate and Long-term Effects of Exercise on ADHD Symptoms and Cognition

Immediate and Longer-term Effects of Exercise on ADHD Symptoms and Cognition

A team of Spanish researchers has published a systematic review of 16 studies with a total of 728 participants exploring the effects of physical exercise on children and adolescents with ADHD. Fourteen studies were judged to be of high quality, and two of medium quality.

Seven studies looked at the acute effects of exercise on eight to twelve-year-old youths with ADHD. Acute means that the effects were measured immediately after periods of exercise lasting up to 30 minutes. Five studies used treadmills and two used stationary bicycles, for periods of five to 30 minutes. Three studies "showed a significant increase in the speed of reaction and precision of response after an intervention of 20-30 min, but at moderate intensity (50-75%)." Another study, however, found no improvement in mathematical problem-solving after 25 minutes using a stationary bicycle at low (40-50%) or moderate intensity (65-75%). The three others found improvements in executive functioning, planning, and organization in children after 20- to 30-minute exercise sessions.

Nine studies examined longer-term effects, following regular exercise over many weeks. One reported that twenty consecutive weekly yoga sessions improved attention. Another found that moderate to vigorous physical activity (MVPA) led to improved behavior beginning in the third week, and improved motor, emotional and attentional control, by the end of five weeks. A third study reported that eight weeks of starting the school day with 30 minutes of physical activity led to improvement in Connor's ADHD scores, oppositional scores, and response inhibition. Another study found that twelve weeks of aerobic activity led to declines in bad mood and inattention. Yet another reported that thrice-weekly 45-minute sessions of MVPA over ten weeks improved not only muscle strength and motor skills, but also attention, response inhibition, and information processing.

Two seventy-minute table tennis per week over twelve weeks improved executive functioning and planning, in addition to locomotor and object control skills.

Two studies found a significant increase in brain activity. One involved two hour-long sessions of rowing per week for eight weeks, the other three 90-minute land-based sessions per week for six weeks. Both studies measured higher activation of the right frontal and right temporal lobes in children, and lower theta/alpha ratios in male adolescents.

All 16 studies found positive effects on cognition. Five of the nine longer-term studies found positive effects on behavior. No study found any negative effects. The authors of the review concluded that physical activity "improves executive functions, increases attention, contributes to greater planning capacity and processing speed and working memory, improves the behavior of students with ADHD in the learning context, and consequently improves academic performance." Although the data are limited by a lack of appropriate controls, they suggest that, in addition to the well-known positive effects of physical activity, one may expect to see improvements in ADHD symptoms and associated features, especially for periods of sustained exercise.

July 18, 2021

How Effective Is Exercise in Treating ADHD?

New meta-analysis explores effectiveness of physical exercise as treatment for ADHD

Noting that "Growing evidence shows that moderate physical activity (PA) can improve psychological health through enhancement of neurotransmitter systems," and "PA may play a physiological role similar to stimulant medications by increasing dopamine and norepinephrine neurotransmitters, thereby alleviating the symptoms of ADHD," a Chinese team of researchers performed a comprehensive search of the peer-reviewed journal literature for studies exploring the effects of physical activity on ADHD symptoms.

They found nine before-after studies with a total of 232 participants, and fourteen two-group control studies with a total of 303 participants, that met the criteria for meta-analysis.

The meta-analysis of before-after studies found moderate reductions in inattention and moderate-to-strong reductions in hyperactivity/impulsivity. It also reported moderate reductions in emotional problems and small-to-moderate reductions in behavioral problems.

The effect was even stronger among unmediated participants. There was a very strong reduction in inattention and a strong reduction in hyperactivity/impulsivity.

The meta-analysis of two-group control studies found strong reductions in inattention, but no effect on hyperactivity/impulsivity. It also found no significant effect on emotional and behavioral problems.

There was no sign of publication bias in any of the meta-analyses.

The authors concluded, "Our results suggest that PA intervention could improve ADHD-related symptoms, especially inattention symptoms. However, due to a lot of confounders, such as age, gender, ADHD subtypes, the lack of rigorous double-blinded randomized-control studies, and the inconsistency of the PA program, our results still need to be interpreted with caution."

February 21, 2022

Meta-analysis suggests regular exercise improves core symptoms and executive functions in child and adolescent ADHD

Meta-analysis Suggests Regular Exercise Improves Core Symptoms and Executive Functions in Child and Adolescent ADHD

A Chinese study team has performed an updated meta-analysis of randomized clinical trials (RCTs) published through July 2022, looking specifically at the effects of chronic exercise on ADHD core symptoms and executive functions in children and adolescents.

The researchers defined chronic to mean exercise interventions lasting at least six weeks, with the longest clocking in at well over a year (72 weeks). 

They only included RCTs with blinding of all assessors who measured the primary outcomes, to guard against any conscious or unconscious bias.

A total of 22 studies met criteria for inclusion in the series of meta-analyses they performed. The RCTs were widely distributed, with four from North America, three from Africa, three from Europe, eleven from Asia, and one from Oceania.

Three studies were rated as being at low risk of bias, the other 19 at moderate risk of bias.

Meta-analysis of eleven RCTs with a combined 514 participants reported a small-to-medium reduction in ADHD core symptoms. Between-study variation (heterogeneity) was moderate, and there was no indication of publication bias.

Breaking that down by age group, for children (eight RCTs, 357 children) the reduction in core symptoms was likewise small-to-medium, versus a medium effect size reduction among adolescents (three RCTs, 157 adolescents), with no heterogeneity.

When the control group received no treatment or was sedentary (8 RCTs, 422 participants), the effect size remained small-to-medium, whereas when the control group received education, it became large (two RCTs, 58 participants). 

Improvements in executive functions were even more pronounced. Meta-analysis of 17 RCTs with a combined 795 participants yielded a medium-to-large effect size reduction in executive functions overall. Heterogeneity was moderate, with absolutely no sign of publication bias.

More specifically, there was a medium effect size improvement in working memory (10 RCTs, 290 participants), a medium-to-large effect size improvement in cognitive flexibility (8 RCTs, 206 participants), and a large effect size improvement in inhibition (12 RCTs, 299 participants). 

Once again, adolescents benefited more than children. Whereas children showed medium effect size improvements in executive function (14 RCTs, 659 children), adolescents registered enormous improvements (3 RCTs, 136 adolescents).

One note of caution, though. Among RCTs rated low risk of bias, effect size improvements in both ADHD core symptoms (3 RCTs, 180 participants) and executive functions (2 RCTs, 86 participants) were small and did not reach statistical significance. That suggests a need for more and better RCTs to reach a more settled verdict.

For now, the authors concluded, “This meta-analysis suggests that CEIs [chronic exercise interventions] have small-to-moderate effects on overall core symptoms and executive functions in children and adolescents with ADHD.”

February 12, 2024

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.

May 16, 2025

How Early Parent–Child Interactions May Shape the Expression of ADHD Traits: A Longitudinal Study

We know that Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition with strong biological and genetic underpinnings; However, emerging research suggests that early environmental influences—particularly parent–child interactions—may shape how ADHD traits, such as impulsivity and delay aversion, are expressed during development.

This longitudinal study explored whether negative parental reactions during moments of delay contribute to the intensification of ADHD-related behaviors in preschool-aged children. A total of 112 mother–child pairs from the UK and Hong Kong participated. Children were screened for ADHD traits using the Strengths and Difficulties Questionnaire, ensuring a range of symptom severity. 

The experimental task—the Parent–Child Delay Frustration Task (PC-DeFT)—was designed to assess how children responded to brief, unpredictable waiting periods during a game-like activity, and how parents reacted in turn. During the task, children operated a button to change a red light to green, allowing their parent to retrieve a toy item. While most trials had no delay, six included unexpected 5–10 second pauses, creating mild frustration. Trained observers recorded children’s behavioral responses and parents' emotional reactions.

At follow-up (12–18 months later), teacher ratings revealed that children whose parents showed more negative reactions during delay trials (e.g., impatience, criticism) were more likely to exhibit increases in ADHD traits—especially impulsivity and difficulty waiting. Importantly, this link was mediated by increases in delay aversion, a motivational style where the child seeks to avoid frustrating waiting experiences. No such associations were found in free play or non-delay tasks, underscoring the specificity of this interaction.

The study’s findings suggest that, while these interactions do not cause ADHD, early social environments can influence how and when symptoms manifest. Interventions aimed at supporting positive parent–child interactions—particularly in challenging contexts like waiting—may help shape the developmental trajectory of children predisposed to ADHD.

May 15, 2025

Study Finds LSD Microdosing No More Effective Than Placebo For ADHD

Double-blind Randomized Clinical Trial Finds LSD Microdosing No More Effective Than Placebo in Treating ADHD Symptoms

Background:

Stimulants, such as methylphenidate and amphetamines, are currently considered effective medications for treating ADHD. However, approximately one-third of patients do not have an adequate response to these treatments. Additionally, long-term adherence is relatively low, with only about half of the patients still using methylphenidate after six years. 

Recently, there has been increasing attention to the concept of microdosing with psychedelic drugs such as psilocybin and LSD. A microdose typically ranges from one-tenth to one-twentieth of a recreational dose and does not produce noticeable perceptual effects or interfere with daily activities.  

The Study:

A European research team recently published the findings of the first double-blind, placebo-controlled randomized clinical trial examining the safety and efficacy of repeated low doses of LSD in adults diagnosed with ADHD. 

The six-week trial took place at University Hospital in Basel, Switzerland, and Maastricht University, Netherlands. Participants, aged 18 to 65, had clinical diagnoses of ADHD with moderate to severe symptoms.  

The team excluded persons with a past or present diagnosis of psychotic disorders, substance use disorders, or other psychiatric or somatic disorders likely to require hospitalization or treatments. 

Participants were randomly assigned in a 1:1 ratio to receive either LSD or placebo. Neither study staff nor participants were aware of the assignments until the conclusion of the trial. 

During the six-week trial, participants received twice-weekly doses on-site, amounting to a total of 12 doses. Following the first and final doses, participants were asked to determine whether they had been administered LSD or a placebo in order to assess blinding. Four weeks after the conclusion of the microdosing period, participants returned for an evaluation of the treatment's safety and efficacy. 

Twenty-seven of the 53 participants were randomized to receive the LSD microdosing treatment in a liquid solution, and 26 to receive placebo. Placebo consisted of the same drinking solution, minus the microdose of LSD. 

The average age was 37, and 42% of participants were female. Forty-six of the 53 participants completed the study. 

Out of 29 participants, 21 from the LSD group and eight from the placebo group correctly guessed their allocation, totaling 63% overall.  

As assessed through the Adult ADHD Investigator Symptom Rating Scale, ADHD symptoms improved by 7.1 points in the LSD group and 8.9 points in the placebo group, with no significant difference between them. 

Regarding safety, the LSD group experienced nearly double the adverse events compared to the placebo group. None of the events in either group were classified as serious. The five most frequent adverse events were headache, nausea, fatigue, insomnia, and visual alterations, occurring around three times more frequently in the LSD group than in the placebo group. 

The team concluded, “although repeated low-dose LSD administration was safe in an outpatient setting, it failed to demonstrate efficacy compared with placebo in improving ADHD symptoms among adults.” 

Conclusion: Microdosing with LSD did not offer significant advantages over placebo in treating ADHD symptoms, despite being physically safe and well tolerated in the trial setting. This suggests that further research is needed to explore alternative treatments for ADHD.

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April 23, 2025