February 28, 2021
Behavioral disinhibition is a trait associated with both ADHD and several genes that affect dopamine signaling. Anew study by three American medical researchers set out to examine how threaded risk genes – DRD4 (dopamine 4 receptor density), DAT1 (dopamine 1transporter), 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, as 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 on expected longevity. Participants also provided blood samples that enabled gene typing.
For the DAT1gene, participants who had the homozygous nine-repeat allele (9/9) had an 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 DBHTaq1 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 for estimated life expectancy.
In a related study, several background traits were found to be significantly predictive of variance in 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 10/10 pairings, 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 9/10pairings 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 in public policy.
“With these limitations in mind,” they concluded, “the present study demonstrated that two ADHD risk genes (DBH and 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 MariellenFischer, “ADHD risk genes involved in dopamine signaling and metabolism are associated with reduced estimated life expectancy at young adult follow-up hyperactive and control children,” American Journal of Medical Genetics (2019), DOI: 10.1002/ajmg.b.32711.
Prevalence of cannabis use among pregnant women is on the rise with the spread of legalization. The most frequently reported reasons for use are to relieve stress or anxiety, nausea or vomiting, pain, and for recreation.
Given that the primary psychoactive ingredient of cannabis, ∆9-tetrahydrocannabinol (THC) is a small fat-soluble molecule that can easily cross the placenta, an Israeli-U.S. research team conducted a systematic search of the peer-reviewed medical literature for studies exploring possible neuropsychiatric effects on offspring.
They included not only studies evaluating likelihood of ADHD, but also autism spectrum disorder, anxiety, depression, and psychotic symptoms. For each of these, adjustment was made for known confounding variables.
With that adjustment, meta-analysis of six studies with a total of over half a million (503,661) participants reported a 13% increase in the odds of ADHD in offspring of mothers using cannabis during pregnancy compared with offspring of mothers not using cannabis while pregnant.
That is generally considered a small effect size increase in risk. But there are multiple reasons to question even this minimal finding:
Meta-analysis of two studies with a total of 741 individuals reported a 20% increase in offspring use of cannabis among mothers who used cannabis during pregnancy, but once again this was subject to methodological shortcomings:
Some studies have suggested a link between cannabis and psychotic symptoms. But meta-analysis of four studies combining over nineteen thousand persons found no significant association between maternal cannabis use during pregnancy and offspring psychotic symptoms.
Many studies have pointed to commonalities in the etiology of ADHD and autism spectrum disorder (ASD). Yet meta-analysis of five studies encompassing over half a million participants found absolutely no association between maternal prenatal cannabis use and ASD.
The remaining meta-analyses also reported no association with depression or anxiety.
With the caution that absence of evidence is not the same as evidence of absence, it is by no means clear from what is presently known that prenatal cannabis exposure has any significant neuropsychiatric effects on offspring. And if further research finds any effects, they are likely to be minor.
Dasotraline is a serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI) that had been under development by Sunovion for treating ADHD and binge eating disorder.
An Indian research team conducted a systematic search of the peer-reviewed medical literature to perform meta-analyses of the quantitative outcomes of clinical trials.
Meta-analysis of five double-blinded randomized clinical trials (RCTs) with a combined total of 1,498 participants reported a small-to-medium effect size reduction in ADHD symptoms in patients given dasotraline as opposed to those given placebo.
There were, however, strong indications of publication bias. Using the trim-and-fill procedure to correct for that bias yielded a small effect size reduction in ADHD symptoms in patients given dasotraline compared with those given placebo.
Insomnia were more than four times more frequent among patients given dasotraline than among those given placebo. There was no evidence of the frequency of insomnia being dose-dependent.
Similarly, patients given dasotraline were more than four times more likely to report decreased appetite than those receiving placebo. In this case, however, the effect was clearly dose-dependent, rising from 3x for 2mg to 4x for 4mg to 5x for 6mg and almost 8x for 8mg.
The authors concluded, “dasotraline can reduce the core symptoms of ADHD, that is, hyperactivity/impulsivity and inattentiveness, leading to an overall improvement of ADHD compared to placebo. Dasotraline can also improve clinician-determined patients’ global functioning compared to the placebo. The most common adverse drug reactions related to dasotraline were insomnia and decreased appetite. However, to fill the knowledge gap, multicentric randomized active-controlled clinical trials are warranted in this domain for a successful translation into clinical practice.”
Weighing these less than impressive initial results against the cost of further RCTs, Sunovion withdrew its application for approval by the Food and Drug Administration, stating, “while Sunovion considers dasotraline to be a promising, novel treatment for binge eating disorder and ADHD, we believe that further clinical studies would be needed to support a regulatory approval for dasotraline in these indications.”
Children and adolescents with ADHD are known to have difficulties in relating to family members, peers, and teachers. Over the long run this can contribute to anxiety or even delinquency.
Several cognitive functions that allow individuals to process social information and interact with others contribute to shaping everyday social interactions. These include:
A European research team performed a systematic search of the peer-reviewed medical literature to conduct meta-analyses of ToM, Empathy, Facial and Non-Facial Emotion Recognition in children and adolescents with ADHD when compared to typical development. As a comparison measure, they also included Everyday Social Skills (using self, parent, teacher, or clinician questionnaires/interviews of social skills) as an outcome.
The search yielded 142 case-control studies (including dissertations) with a total of 16,283 participants.
Meta-analysis of 82 studies with a combined total of 10,770 participants found a very large effect size impairment in everyday social skills among children and adolescents with ADHD when compared with typically developing peers. Adjusting for covariates only strengthened the finding. There was no sign of publication bias.
This was mirrored in three out of five measures of social cognition:
The team concluded, “Our findings show that children and adolescents with ADHD have deficits in ToM, Facial Emotion Recognition, and Everyday Social Skills, three domains that warrant clinical attention.”
_logo%201.svg)
