March 9, 2022
Previous meta-analyses have found an association between cesarean delivery (CD) and subsequent ADHD in children delivered in that manner. Some have theorized that by bypassing the birth canal, children delivered via CD may acquire their first microbiota from the hospital environment rather than from their mothers, which could disturb the normal development of the nervous system, including the brain.
Nevertheless, earlier studies have not fully explored the role of confounding factors.
A team of Swedish researchers availed themselves of the country's all-encompassing system of national population and health care registers to examine a cohort of over a 1.1 million single births from 1990 through 2003 and followed up through 2013.
They distinguished between planned CD and intrapartum (i.e., during the act of birth) CD. The latter is performed in response to complications with childbirth. This distinction could matter both because of different levels of exposure to the maternal gut microbiota, and because "intrapartum CD is often the result of complications during pregnancy (e.g., preeclampsia) or delivery (e.g., fetal distress), which could affect brain development."
Of 1,179,341 individuals, 1,048,838 were delivered vaginally, 59,514 were delivered by planned CD, and 70,989 were delivered by intrapartum CD.
After adjusting for the child's year of birth, gestational age, age of mother and father at birth, parity, mother's highest education level at birth, maternal smoking during pregnancy, maternal and paternal history of psychiatric disorders, maternal hypertension, maternal diabetes, maternal infections during pregnancy, fetal MAL presentation, large for gestational age, polyhydramnios, oligohydramnios, preeclampsia, and pelvic disproportion, children born by planned CD were 17% more likely to have ADHD.
After adjusting for all previously listed variables plus placenta disorders, dystocia failed induction, and fetal distress, children born by intrapartum CD were 10% more likely to have ADHD.
So far, the analysis confirmed results from previous meta-analyses.
But by exploring such a large cohort, it also became possible to compare ADHD prevalence, not only among unrelated individuals, but also among siblings and cousins, and thereby assess the role of confounders arising from genetics or shared environment.
Whether between full siblings or full maternal cousins, the associations between both types of CD and subsequent ADHD became weak and statistically non-significant.
The authors concluded, "The findings of this study suggest that the association between CD and increased risk of neurodevelopmental disorders in the children was most likely explained by unmeasured familial confounding."
Tianyang Zhang, Gustaf Brander, Ängla Mantel, RalfKuja-Halkola, Olof Stephansson, Zheng Chang, Henrik Larsson, David Mataix-Cols, Lorena Fernández de la Cruz, "Assessment of Cesarean Delivery and neurodevelopmental and Psychiatric Disorders in the Children of population-Based Swedish Birth Cohort,". JAMA Network Open(2020)4(3):e210837,https://doi:10.1001/jamanetworkopen.2021.0837.
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.”
