February 11, 2022
Methylphenidate, a psychostimulant, is among the drugs most frequently prescribed to children with ADHD.
Using magnetic resonance imaging(MRI), studies have shown that as children mature, those with ADHD differ from controls in developing regionally thinner cortices (the folded outer layer of the cerebrum that is essential to rational thought) and smaller lower basal ganglia(structures linked to the thalamus in the base of the brain and involved in the coordination of movement). The cortical differences were found in the right medial frontal motor region, the left middle/inferior frontal gyrus, and the right posterior parieto-occipital region in children with ADHD who were not taking psychostimulants.
A Dutch/Norwegian team of researchers conducted a randomized, double-blind, placebo-controlled trial with 96 males recruited from Dutch clinical programs. 48 were boys aged 10-12 years, and 47 were men between the ages of 23 and 40. None had previously been on methylphenidate. There were no significant differences in baseline age, ADHD symptom severity, estimated intelligence quotient, the proportion of right-handedness, or region of interest brain characteristics between the placebo and medication groups.
The trial was carried out during the standard 17-week waiting list time for evaluation and treatment to begin so that those receiving a placebo during the trial would not ultimately be at a disadvantage. The same MRI scanner was used for all measurements, both before and after treatment.
Among the boys, the methylphenidate group showed increased thickness in the right medial cortex, while the placebo group showed cortical thinning. In adults, both groups showed cortical thinning. When converted into an estimated mean rate of change in cortical thickness for the right medial cortex, boys taking methylphenidate could expect to lose about 0.01 mm per year, versus about 0.14 mm for boys not on methylphenidate.
In the right posterior cortex, scans also showed reduced thinning in the methylphenidate treatment group, though to a lesser extent. But there was no reduced thinning in the left frontal cortex.
The authors noted several limitations. The sample size was small. Second, "because we did not detect significant relationships between changes in cortical [regions of interest] and changes in symptom severity, the functional significance remains uncertain." Third, the follow-up period was relatively short, not allowing any assessment of the longer-term effects of the medication. Fourth, the differences in effects on the three brain regions examined were uneven, contrary to what had been expected from previous studies. They recommended replication with larger groups and longer follow-ups.
K.B. Walhovd, I.Amlien, A. Schrantee,D.A. Rohani, I. Groote, A. Bjørnerud, A.M. Fjell, and L.Reneman, "Methylphenidate Effects on Cortical Thickness in Children and Adults with Attention-Deficit/Hyperactivity Disorder: A Randomized Clinical Trial," American journal of Neuroradiology(2020)41 (5) 758-765,http://dx.doi.org/10.3174/ajnr.A6560.
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.”
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