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August 23, 2021
A Canadian team has published a systematic review examining the effectiveness of Mindfulness-Based Interventions (MBIs) for treating adults with ADHD. MBIs usually involve three forms of meditation “ body scan, sitting meditation, and mindful yoga “ that are intended to cultivate nonjudgmental awareness of the present-moment experience. The team reviewed thirteen studies.
Three were single-group studies with no control group. One used dialectical behavior therapy (DBT). It reported mild to moderate improvements in ADHD symptoms, and substantial improvements in neurocognitive function (with standardized mean difference effect sizes from .99 to 2.22). A second enrolled both adults and adolescents in a mindful awareness program (MAP)which included a psychoeducational component. It found improvements in itself-reported ADHD symptoms, with standardized mean difference (SMD) effect sizes running from .50 to.93. Following training, it also reported improvement in attentional conflict (.93) set-shifting (.43). The third study also used DBT, which focused on acceptance, mindfulness, functional behavioral analysis, and psychoeducation. ADHD symptoms showed mild improvement (.22), and functional impairment was slightly reduced (.15) and remained stable at the 3-month follow-up.
The other ten studies used control groups. One used MAP and carefully stratified participants based on their ADHD medication status, then randomly assigned them to mindfulness treatment or waitlist. It reported large effect sizes in the improvement of self-reported and clinician ratings of ADHD symptoms (1.35 to 3.14), executive functioning (1.45 to 2.67), and self-reported emotion regulation (1.27 to 1.63). Another study non randomly assigned adults to either mindfulness-based training (MBT) or skills training. Effect sizes were small to medium (.06 to .49), with 31% of MBT participants showing some improvement, versus only 11% of skills training participants.
Another study involved a controlled trial of college students with ADHD, randomized to receive either MBT or skills treatments. Treatment response rates were higher for MBT (59-65%, vs. 19-25%). In follow-up, the effect size for MBT on ADHD symptoms was large (.84), and similarly large on executive functioning (.81).
Another study tried a year's worth of mindfulness training for poor responders to medication. Participants who received the treatment were compared to others who were waitlisted. The study reported a medium effect size(.63) in reducing the severity of ADHD.
Another looked at the impact of MAP on affective problems and impaired attention. It compared adults with ADHD and healthy controls who participated in MAP sessions with similar patients and controls who did not. The authors reported that MAP improved sustained attention and mood, with medium to large effect sizes (.50 to .80).
A recent study explored the impact of MAP on neurocognitive performance with a randomized controlled trial. Following an 8-week mindfulness training, researchers found a significant decrease in ADHD symptoms and significant improvement in task performance in both the MAP and the psychoeducation comparison group post- versus pre-intervention but did not find evidence for a significant main effect of treatment or a significant interaction effect on any ADHD symptoms (self-and observer-rated) nor on task performance (WM).
Another study randomly assigned adults with ADHD either to the waitlist or mindfulness-based cognitive therapy (MBCT). It found that MBCT led to a medium-to-large reduction in self-reported ADHD symptoms (.64) and a large reduction in investigator-reported symptoms (.78). It also found large(.93) improvements in executive functioning.
An 11th study looked at the effects of MBCT on neuropsychological correlates (event-related potentials (ERPs)) of performance monitoring in adults with ADHD. Half the patients were randomly assigned tomb cut, and the other half to the waitlist. MBCT produced reduced inattention, hyperactivity/impulsivity, and global ADHD index symptoms with medium to large effect sizes (.49 to .93).
A 12th study randomly assigned college students to MBCT or waitlist. At follow-up, participants who had received MBCT exhibited large (1.26) reductions in ADHD symptoms as well as greater treatment response rates (57%-71% vs. 23%-31%) versus waitlist. They also registered a greater improvement in most neuropsychological performance and attentional scores.
Finally, another study compared the efficacy of MBCT plus treatment as usual (TAU) versus TAU only in reducing core symptoms in adults with ADHD. Participants were randomly assigned to an 8-weekly group therapy including meditation exercises, psycho-education, and group discussions, or TAU only, including pharmacotherapy and/or psychoeducation. At 6-month follow-up, MBCT+TAU patients reported large (SMD = .79) improvements in ADHD symptoms relative to patients.
Overall, these are promising results of mindfulness-based interventions, and all the more so for those who do not respond well to drug therapy. Nevertheless, they must be seen as tentative. The total of participants overall in thirteen studies was just 753, or an average of only 58 per study. There was too much variation in the studies to perform a meta-analysis. Only one of the studies included a healthy (non-ADHD) control group. And only one study received a perfect score from Cochrane Collaboration standards. Most studies did not use a suitable control group, i.e., one in which there was an expectation of benefit from participating. As the authors noted, "Attrition bias was found to have high or unclear risk in more than a half of the studies. The reason for dropout of participants was not always clearly specified in those studies, so it is difficult to decide if it might be related to adverse effects or some discomfort with treatment or instead to some incidental reasons."
HeÌleÌ€nePoissant, Adrianna Mendrek, NadineTalbot, Bassam Khoury, and Jennifer Nolan, "Behavioral and Cognitive Impacts of mindfulness-Based Interventions on Adults with Attention-Deficit HyperactivityDisorder: A Systematic Review," Behavioural Neurology, Vol. 2019, ArticleID 5682050, 16 pages, https://doi.org/10.1155/2019/5682050.
The Background:
Meta-analyses have previously suggested a link between maternal thyroid dysfunction and neurodevelopmental disorders (NDDs) in children, though some studies report no significant difference. Overweight and obesity are more common in children and adolescents with NDDs. Hypothyroidism is often associated with obesity, which may result from reduced energy expenditure or disrupted hormone signaling affecting growth and appetite. These hormone-related parameters could potentially serve as biomarkers for NDDs; however, research findings on these indicators vary.
The Study:
A Chinese research group recently released a meta-analysis examining the relationship between neurodevelopmental disorders (NDDs) and hormone levels – including thyroid, growth, and appetite hormones – in children and adolescents.
The analysis included peer-reviewed studies that compared hormone levels – such as thyroid hormones (FT3, FT4, TT3, TT4, TSH, TPO-Ab, or TG-Ab), growth hormones (IGF-1 or IGFBP-3), and appetite-related hormones (leptin, ghrelin, or adiponectin) – in children and adolescents with NDDs like ADHD, against matched healthy controls. To be included, NDD cases had to be first-diagnosis and medication-free, or have stopped medication before testing. Hormone measurements needed to come from blood, urine, or cerebrospinal fluid samples, and all studies were required to provide both means and standard deviations for these measurements.
Meta-analysis of nine studies encompassing over 5,700 participants reported a medium effect size increase in free triiodothyronine (FT3) in children and adolescents with ADHD relative to healthy controls. There was no indication of publication bias, but variation between individual study outcomes (heterogeneity) was very high. Further analysis showed FT3 was only significantly elevated in the predominantly inattentive form of ADHD (three studies), again with medium effect size, but not in the hyperactive/impulsive and combined forms.
Meta-analysis of two studies combining more than 4,800 participants found a small effect size increase in thyroid peroxidase antibody (TPO-Ab) in children and adolescents with ADHD relative to healthy controls. In this case, the two studies had consistent results. Because only two studies were involved, there was no way to evaluate publication bias.
The remaining thyroid hormone meta-analyses, involving 6 to 18 studies and over 5,000 participants in each instance, found no significant differences in levels between children and adolescents with ADHD and healthy controls.
Meta-analyses of six studies with 317 participants and two studies with 192 participants found no significant differences in growth hormone levels between children and adolescents with ADHD and healthy controls.
Finally, meta-analyses of nine studies with 333 participants, five studies with 311 participants, and three studies with 143 participants found no significant differences in appetite-related hormone levels between children and adolescents with ADHD and healthy controls.
The Conclusion:
The team concluded that FT3 and TPO-Ab might be useful biomarkers for predicting ADHD in youth. However, since FT3 was only linked to inattentive ADHD, and TPO-Ab’s evidence came from just two studies with small effects, this conclusion may overstate the meta-analysis results.
Our Take-Away:
Overall, this meta-analysis found only limited evidence that hormone differences are linked to ADHD. One thyroid hormone (FT3) was higher in children with ADHD—mainly in the inattentive presentation—but the findings varied widely across studies. Another marker, TPO-Ab, showed a small increase, but this came from only two studies, making the result less certain. For all other thyroid, growth, and appetite-related hormones, the researchers found no meaningful differences between children with ADHD and those without. While FT3 and TPO-Ab may be worth exploring in future research, the current evidence is not strong enough to consider them reliable biomarkers.
Background:
Recent progress in reproductive medicine has increased the number of children conceived via assisted reproductive techniques (ART). These include:
Although ART helps with infertility, there are concerns about its long-term effects on offspring, especially regarding neurodevelopment. Factors such as hormonal treatments, gamete manipulation, altered embryonic environments, as well as parental age and infertility, may influence brain development and raise the risk of neurodevelopmental and mental health disorders.
With previous studies finding conflicting results on a possible association between ART and increased risk of mental health disorders, an Indian research team has just published a new meta-analysis exploring this topic.
The Study:
Studies were eligible if they were observational (cohort, case-control, or cross-sectional), reported confounder-adjusted effect sizes for ADHD, and were published in English in peer-reviewed journals.
A meta-analysis of eight studies encompassing nearly twelve million individuals indicated a 7% higher prevalence of ADHD in offspring conceived via IVF/ICSI compared to those conceived naturally. The heterogeneity among studies was minimal, and no evidence of publication bias was observed.
The study’s 95% confidence interval ranged from 4% to 10%. Further analysis of five studies comprising almost nine million participants that distinguished outcomes by sex revealed that the increase in ADHD risk among female offspring was not statistically significant. In contrast, the elevated risk in male offspring persisted, though it was marginally significant, with the lower bound of the confidence limit at only 1%.
Results:
A meta-analysis of three studies (1.4 million participants) found a 13% higher rate of ADHD in children conceived via ovulation induction/intrauterine insemination (OI/IUI) compared to natural conception. The effect size, though doubled, remains small. Minimal heterogeneity and no publication bias were observed.
The team concluded, “The review found a small but statistically significant moderate certainty evidence of an increased risk of ADHD in those conceived through ART, compared to spontaneous conception. The magnitude of observed risk is small and is reassuring for parents and clinicians.”
Our Take-Away:
Overall, the meta-analysis points to a small, but measurable increase in ADHD diagnoses among children conceived through ART, but the effect sizes are modest and supported by moderate-certainty evidence. And we must always keep in mind that the researchers who wrote the original articles could not correct for all possible confounds. These findings suggest that while reproductive technologies may introduce slight variation in neurodevelopmental outcomes, the effects are small and uncertain. For families and clinicians, the results are generally reassuring: ART remains a safe and effective avenue to parenthood, and the results of this study should not be viewed as a prohibitive concern. Thoughtful developmental monitoring and open, evidence-based counseling can help ensure that ART-conceived children receive support that caters to their individual needs.
The Background:
Myopia is a growing global health concern linked to conditions like macular degeneration, glaucoma, and retinal detachment. Its prevalence has surged in recent decades; by 2050, an estimated 5 billion people will have myopia. The increase is especially marked in Asia – a survey in Taiwan reports that 84% of students aged 15 to 18 are myopic, with 24% severely affected.
Dopamine is an important neurotransmitter in the retina, involved in eye development, visual signaling, and refractive changes. The dopamine hypothesis, suggesting that retinal dopamine release helps prevent myopia, has emerged as a leading theory of myopia control.
Most studies show ADHD is highly heritable, often involving dopamine system genes. ADHD is strongly associated with dopaminergic abnormalities, especially in dopamine transporter function and release dynamics.
Medications for ADHD, like methylphenidate, atomoxetine, and clonidine, help regulate dopamine to reduce symptoms.
The Study:
Given dopamine’s critical involvement in both ADHD and myopia, a Taiwanese research team hypothesized that medications for ADHD that influence dopaminergic pathways may have a significant effect on myopia risk.
To evaluate this hypothesis, the team conducted a nationwide cohort study using data from Taiwan’s National Health Insurance (NHI) program, which covers 99% of the nation’s 23 million residents and provides access to comprehensive eye care and screenings. Taiwan requires visual acuity screenings beginning at age four, with annual examinations for school-aged children to promote the early detection of visual anomalies such as myopia.
Furthermore, ADHD medication and diagnosis are tracked through compulsory diagnostic codes. This permits an accurate assessment of the effects of dopaminergic medications on myopia risk.
Propensity score allocation using a multivariable logistic regression model was applied to reduce bias from confounding influences, pairing cohorts based on similar scores.
The Results:
Comparing 133,945 individuals with ADHD with an equal number without ADHD, untreated ADHD was associated with a 22% greater risk of myopia.
However, after adjusting for covariates (gender, age, insured premium, comorbidities, location, and urbanization level), the ADHD cohort receiving medication treatment showed a 39% decreased risk of myopia relative to the untreated ADHD cohort.
Narrowing this further to the ADHD cohort receiving dopaminergic medications reduced the risk of myopia by more than half (52%) relative to the untreated ADHD cohort.
Treatment with two dopaminergic medications reduced the risk by well over two-thirds (72%) relative to the untreated ADHD cohort.
There were no significant differences between methylphenidate, atomoxetine, and clonidine. Each reduced risk by about 50%.
The team did not directly compare the ADHD cohort receiving dopaminergic medications with the non-ADHD cohort. But if there were 122 cases of myopia in the ADHD cohort for every 100 cases in the non-ADHD cohort, and dopaminergic medications halved the cases in the ADHD cohort to about 60, that would represent a roughly 40% reduction in myopia risk relative to the non-ADHD cohort.
The team concluded, “our research indicates that pharmacologically treated ADHD children have a reduced risk of myopia. Conversely, untreated ADHD children are at a heightened risk relative to those without ADHD. Moreover, the cumulative effects of ADHD medications were found to notably decrease myopia incidence, emphasizing the protective influence of dopaminergic modulation in these interventions.”
The Take-Away:
Children with untreated ADHD are more likely to develop myopia, but those receiving dopaminergic medications had a substantially lower risk. The findings suggest that ADHD medications may help protect against myopia by boosting dopamine signaling. More research is needed before firmly drawing this conclusion, but this research could open the door to new approaches for preventing myopia in at-risk children.
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