August 19, 2021
Behavioral disinhibition is a trait associated with both ADHD and several genes that affect dopamine signaling. A new study by three American medical researchers set out to examine how these ADHD risk genes - DRD4 (dopamine 4 receptor density), DAT1 (dopamine 1 transporter), and DBH(dopamine beta-hydroxylase) - affect estimated life expectancy in young adulthood.
The method used was a longitudinal study of 131 hyperactive children and 71 matched controls through early adulthood. The original evaluations were done in 1979-1980, when both groups were children in the 4 to 12 age range. They were reevaluated in1987-1988 as adolescents aged 12 to 20. The next follow-up was in 1992-1996 in early adulthood, aged 19 to 25. The final follow-up was in 1998-2004, for adults aged 24 to 32. All agreed to physical examinations that formed the basis for calculating estimated life expectancy using actuarial tables that factor in the effects of smoking, body mass index, alcohol, and other risk factors of on expected longevity. Participants also provided blood samples that enabled gene typing.
For the DAT1 gene, participants who had the homozygous-repeat allele (9/9) had a five-year reduction in estimated life expectancy relative to those with the ten-repeat allele (10/10). Those with the intermediate (9/10) configuration had a three-year reduction in estimated life expectancy.
For the DBH Taq1 gene, those with a heterozygous (A1/A2) combination had almost a three-year reduction in estimated life expectancy relative to those with homozygous (A1/A1 or A2/A2)configurations.
For DRD4, on the other hand, no significant differences were found in estimated life expectancy.
In a related study, several background traits were found to be significantly predictive of variance estimated life expectancy. The largest of these was behavioral disinhibition, followed by verbal IQ, self-rated hostility, and a nonverbal fluency test. But no significant differences were found between any of the gene polymorphisms on any of these four measures, indicating that the present gene associations were independent of the background traits.
The researchers next sought to determine which variables used in the estimated life expectancy calculations were associated with the two significant genes. For DBH, one variable stood out. Those with the A1/A2 heterozygous pairings had almost twice the alcohol consumption of those with homozygous pairings (p = 0.023).
For DAT1, two variables stood out. Overall, the 9/9 pairings smoked two and a half times as much as the 10/10pairings, with the 9/10 pairings midway between the extremes (p = 0.036). They were also 73 percent more likely to be smokers relative to the 10/10 pairings, and 61 percent more likely relative to the 9/10 pairings. They also had significantly less education than the 10/10 pairings, with the 9/10 pairings again being intermediate (p = 0.027).
An obvious limitation of the study was its small sample size. The authors cautioned, our findings should be considered quite preliminary and in need of much greater research before being given much weight in the literature or public policy.
"With these limitations in mind, they concluded, the present study demonstrated that two ADHD risk genes (DB Hand DAT1) independently contributed to a reduction in ELE [estimated life expectancy] beyond the second-order variables of behavioral disinhibition, IQ, hostility, and nonverbal fluency that contributed in the related study to variation in ELE. The gene polymorphisms seemed to be influencing ELE through their affiliation with first-order or more proximal factors related to ELE such as education, smoking, alcohol use, and possibly exercise."
Russell A. Barkley, Karen Müller Smith, and Mariellen Fischer, ADHD risk genes involved in dopamine signaling and metabolism are associated with reduced estimated life expectancy at young adult follow-up in hyperactive and control children, American Journal of Medical Genetics(2019), DOI:10.1002/aiming.b.32711.
Given the persistence of ADHD and its adverse effects on children and adolescents, one might expect caregivers to face greater parenting challenges, with potential effects on their own mental health.
To what extent do parenting stress, depression, and – at the extreme – even suicidal ideation manifest themselves among caregivers of ADHD patients as opposed to caregivers of children and adolescents without ADHD?
A pair of Korean researchers made use of their country’s single-payer health insurance system, which maintains records on virtually the entire population, to perform a nationwide population study. They used data from the Korean National Health and Nutrition Examination Surveys (KNHANES) covering the decade from 2011 to 2020. KNHANES is an annual survey using a sophisticated sampling design conducted by the Korean Ministry of Health and Welfare to represent the entire population of South Korea.
The analysis included 14,428 individuals who had children younger than 19 at the time of participation. All were asked whether their child had ever been diagnosed with ADHD by a physician. The mental health problems of the parents were assessed in terms of perceived stress, depressive symptoms, and suicidality.
Of the 14,428 participants, 8,298 (57.5 %) were mothers and 6,130 (42.5 %) were fathers. Of the mothers, 116 (1.4 %) had a child with ADHD, and of the fathers, 86 (1.4 %) had a child with ADHD.
The researchers adjusted for the following confounders: age of caregiver, education level, household income, area of residence, employment status, alcohol consumption, smoking status, cohabitation status, number of children, and child’s age.
After adjustment, mothers of ADHD patients fared significantly worse than mothers of typically developing children on all three categories of mental health problems. They were 67% more likely to report higher stress, three times as likely to report symptoms of depression, and 2.5 times more likely to report suicidal ideation.
Yet that pattern did not carry over to fathers, where there was no significant difference in mental health indicators between fathers of children with ADHD and fathers of children without ADHD.
The authors concluded, “Parents of children with ADHD, especially mothers, need community support and public health attention to help alleviate their mental health problems.”
Background:
ADHD is commonly accompanied by psychiatric comorbidities that complicate its diagnosis and treatment. Roughly two out of three affected children and adolescents have one or more comorbid psychiatric disorder.
Because the peak age of ADHD onset is typically a decade or more earlier than those for schizophrenia, depressive disorder, or bipolar disorder, it is essential to explore these comorbidities over an extended period. Populations studies help researchers identify broader patterns and trends within an entire population and includes adults as well as children. This type of study provides unique insights into the population at large, rather than a sample group.
In earlier studies the maximum follow-up period was twelve years, insufficient in view of the roughly ten years between onset of ADHD and onset of major psychiatric disorders. Also, previous nationwide population studies have included less than 150,000 participants.
This study, relying on data from South Korea’s universal single-payer health insurance system, included over one and a half million individuals. Persons previously diagnosed with depression, bipolar disorder, tic disorder, or schizophrenia were excluded.
382,434 individuals had been diagnosed with ADHD, while 1,169,279 were without an ADHD diagnosis.
Propensity score matching ensured that potential confounders, both sociodemographic and clinical, were equalized for the ADHD and control groups. After matching, there were 353,898 individuals in each group.
After these adjustments, individuals in the ADHD group were at least an order of magnitude more likely to subsequently be diagnosed with psychiatric disorders than their peers without an ADHD diagnosis:
Conclusion:
The Korean study team concluded, “Overall, our findings suggest that upon prolonged examination, the risk of subsequent diagnoses of other psychiatric disorders in individuals with ADHD appears to be higher than that reported previously. … Therefore, patients with ADHD should be carefully screened for the presence of other psychiatric symptoms on a regular basis from an earlier age … It is advisable to have a follow-up period extending beyond 10 years to sufficiently identify the occurrence of comorbid disorders in patients with ADHD.”
Children with ADHD often face challenges in social interactions, leading to long-term consequences if not properly addressed. While various interventions exist, many fail to consider the broader social context in which these children interact. A recent study conducted in Bergen, Norway, explored how primary school teachers perceive their role in supporting children with ADHD who struggle socially and the strategies they use to assist them.
Researchers conducted semi-structured interviews with five focus groups of primary school teachers. Using reflexive thematic analysis, they identified two major themes:
Rather than relying on standardized interventions, teachers tailored their strategies to foster an inclusive and supportive social environment. Their methods included both active participation in social situations and behind-the-scenes efforts to encourage peer inclusion and understanding.
This study underscores the need to move beyond labels and recognize children with ADHD as individuals with distinct social needs. Teachers play a crucial role in shaping these children’s experiences, using flexible and personalized approaches to promote positive social interactions. By integrating social context and individualized support, educators can help children with ADHD build meaningful connections and navigate their social world more effectively.
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