July 18, 2021
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.
Sara Suarez-Manzano, Alberto Ruiz-Ariza, Manuel La Torre-Cruz, Emilio J. MartiÌnez-LoÌpez, "Acute and chronic effect of physical activity on cognition and behavior in young people with ADHD: A systematic review of intervention studies," Research in Developmental Disabilities, vol. 77, 12-23(2018).
What are we to make of adults who exhibit the diagnostic criteria for ADHD, but are nevertheless high-functioning and successful? A trio of British investigators has just published six case studies that explore this question. It would have been better for them to have conducted a much larger, controlled research study but, in the absence of such data in the area, these case studies are intriguing and may help guide more informative research.
The authors recruited six successful men between the ages of 30 and 65 from a National Health Service tertiary service in London. Four were in long-term relationships, with children. All had good jobs.
In open-ended taped interviews of up to an hour in length, each was asked three questions:
1. What do you think are the advantages and disadvantages of having ADHD?
2. Please describe a time when you felt that your ADHD helped you to achieve something?
3. What aspects of your ADHD would you miss if it went away?
Hyper-focus in ADHD is generally considered a deficit, inset-shifting, and task-switching. But the authors report that participants associated it with productivity. One said, “I think the energy that the ADHD brain seems to have....it’s unfocused, quite scattered, chaotic and a bit random...but give that brain something that you can tune into, and it’s your interest, then all that random stuff just goes boom... I get this incredible intense concentration and that’s great for work.”
Participants also saw advantages in divergent thinking, with one stating, “I’m an artist.... a creative type... a Bohemian.... you are most likely to be a creative person if you are a divergent thinker....and not convergent... I am very creative and that’s through and through... I’m a fine art graduate, a musician, a published poet, an entrepreneur, a performer.”
All the participants reported being seen as nonconformists. Depending on a viewpoint, that can be seen as either detrimental or advantageous.
Impulsivity is a core symptom of ADHD. Participants however related it to bravery, and more specifically adventurousness, spontaneity, and thrill-seeking. One said, “thrill-seeking is an ADHD thing... I can list in my life have done white water rafting, bungee jumping, hand-glider pilot … I have done a lot in my life and achieved a lot and experienced a lot... Furthermore, I would see a lot of that as being quite positive, and a lot of that is ADHD drive.”
Another common theme was high energy and “spirit.” One participant said, “I’ve got all this energy.... a lot of energy... whatever it's to do with... nature/nurture/spiritual stuff.”
These testimonials are useful as a check on the usual narrative of impairment. ADHD does not predestine all it afflicts to an unfulfilling life. Many, often assisted by medication, still lead exciting, successful, rewarding lives. Yet, we must be cautious in concluding that these individuals were successful because of their ADHD. It is possible, even likely, that they had other strengths such as high intelligence that compensated for their ADHD symptoms. We can not know from this report if their lives had been even more fulfilling or successful in the absence of ADHD. See, for example, my blog about highly intelligent people with ADHD: https://www.linkedin.com/pulse/20141126141502-65669938-smart-people-can-have-adhd-too/.
While the authors concede that “generalizing the findings of this study is not easy to do,” they inexplicably “also argue that the positive aspects we found are relevant to other adults with ADHD regardless of sample size, age, gender or ethnicity.” It is not possible to draw such a definitive conclusion without a much larger sample.
On a hopeful note, they conclude, “This is a study that reaches out to people with lived experience of ADHD: service users, patients, family members, carers, partners, to say that not all symptoms of ADHD are maleficent. Recovery, high functionality, and flourishing with ADHD are possible. Too often people with lived experience hear about ADHD deficits, functional impairments, and associations with substance misuse, criminality, or other disadvantages on almost every level of life (school, work, relationships). … This study affirms the positive human qualities, assets, and attributes in ADHD that can promote and sustain high functioning and flourishing.” I fully endorse the idea that those with ADHD can have wonderful lives, especially if they receive appropriate treatment, both medical and psychological.
China is the outstanding economic growth story of the early twenty-first century. According to the World Bank, China has “experienced the fastest sustained expansion by a major economy in history – and has lifted more than 800 million people out of poverty.”
That expansion has been accompanied by major investments in medical research, and medical treatment capability, especially in the major urban centers that have spearheaded the boom. Life expectancy has risen from 71 in 2000 to 77 in 2019, nearing the U.S. level of 79.
Yet when it comes to pharmaceutical treatment of ADHD, China is an outlier, as revealed by a new study exploring the data in the two main medical insurance programs for its urban population.
The Urban Employee Basic Medical Insurance(UEBMI) covers both employers and employees in public and private workplaces, while the Urban Residents Basic Medical Insurance (BMI) covers the unemployed. As of 2014, these programs cover over 97% of urban residents. The China Health Insurance Research Association (CHIRA) database is a random sampling database from the UEBMI and UBMI databases.
The study population consisted of residents of the 63 cities in the CHIRA database from 2013 through 2017. Prescription prevalence was calculated by dividing the total number of patients prescribed ADHD medications in the CH IRA database by the urban population of the included cities, which was two hundred million as of 2017.
Other studies have found the prevalence of ADHD among Chinese children and adolescents to be about 6.5%, comparable to North American and European countries. Yet, the prescription prevalence of ADHD medications was 0.036% among those aged 0–14 years in 2017 in China. In other words, only about one in every two hundred youths with ADHD were being prescribed pharmaceutical treatments.
For further context, among other economically prosperous countries in Asia, Australia, North America, and Europe, the lowest prescription prevalence of ADHD medications is 0.27% in France, which is still over seven times higher than the Chinese level.
Among Chinese urban dwellers from 15 through 64 years of age, ADHD prescription prevalence in 2017 dropped by a further order of magnitude (over tenfold) to 0.003%, and among those 65 and older, to a scant 0.001%.
The Chinese study team suggested several likely contributing factors:
Sleep disorders are one of the most commonly self-reported comorbidities of adults with ADHD, affecting 50 to 70 percent of them. A team of British researchers set out to see whether this association could be further confirmed with objective sleep measures, using cognitive function tests and electroencephalography (EEG).
Measured as theta/beta ratio, EEG slowing is a widely used indicator in ADHD research. While it occurs normally in non-ADHD adults at the conclusion of a day, during the day it signals excessive sleepiness, whether from obstructive sleep apnea or neurodegenerative and neurodevelopmental disorders. Coffee reverses EEG slowing, as do ADHD stimulant medications.
Study participants were either on stable treatment with ADHD medication (stimulant or non-stimulant medication) or on no medication. Participants had to refrain from taking any stimulant medications for at least 48 hours prior to taking the tests. Persons with IQ below 80 or with recurrent depression or undergoing a depressive episode were excluded.
The team administered a cognitive function test, The Sustained Attention to Response Task (SART). Observers rated on-task sleepiness using videos from the cognitive testing sessions. They wired participants for EEG monitoring.
Observer-rated sleepiness was found to be moderately higher in the ADHD group than in controls. Although sleep quality was slightly lower in the sleepy group than in the ADHD group, and symptom severity slightly greater in the ADHD group than the sleepy group, neither difference was statistically significant, indicating extensive overlap.
Omission errors in the SART were strongly correlated with sleepiness level, and the strength of this correlation was independent of ADHD symptom severity. EEG slowing in all regions of the brain was more than 50 percent higher in the ADHD group than in the control group and was highest in the frontal cortex.
Treating the sleepy group as a third group, EEG slowing was highest for the ADHD group, followed closely by the sleepy group, and more distantly by the neurotypical group. The gaps between the ADHD and sleepy groups on the one hand, and the neurotypical group on the other, were both large and statistically significant, whereas the gap between the ADHD and sleepy groups was not. EEG slowing was both a significant predictor of ADHD and of ADHD symptom severity.
The authors concluded, “These findings indicate that the cognitive performance deficits routinely attributed to ADHD … are largely due to on-task sleepiness and not exclusively due to ADHD symptom severity. … we would like to propose a simple working hypothesis that daytime sleepiness plays a major role in cognitive functioning of adults with ADHD. … As adults with ADHD are more severely sleep deprived compared to neurotypical control subjects and are more vulnerable to sleep deprivation, in various neurocognitive tasks they should manifest larger sleepiness-related reductions in cognitive performance. … One clear testable prediction of the working hypothesis would be that carefully controlling for sleepiness, time of day, and/or individual circadian rhythms would result in a substantial reduction in the neurocognitive deficits in replications of classic ADHD studies.”
