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November 1, 2021
Both Taiwan and Sweden have universal single-payer health insurance systems that in effect track their entire national populations. With detailed health and other records on millions of individuals, with no significant exclusions, one can essentially eliminate sampling error, and also explore how associations vary by degree of familial/genetic relationship.
A Taiwanese research team used the Taiwan National Health Insurance Research Database to follow 708,517 family triads (father-mother-child) from 2001 through 2011. That's a total of over 2.1 million persons. The database covers over 99% of Taiwan's population.
Noting that previous studies had found links between maternal autoimmune diseases and ADHD in their offspring and that research on associations with paternal autoimmune diseases had been inconclusive, they were particularly interested in exploring the latter.
Children born from 2001 through 2008 were enrolled in the study. The investigators then noted the presence or absence of any autoimmune disease in their parents from 1996 through childbirth.
In Taiwan, expert panels review diagnostic information of severe systemic autoimmune diseases to confirm the diagnosis. Once confirmed, patient co-payments are waived. ADHD diagnoses are by board-certified psychiatrists.
To reduce the effect of confounding variables, adjustments were made for family demographic data (income level and residence), parental ages, parental mental disorders, and sex of children.
The presence of any maternal autoimmune diseases was associated with a 60% greater risk of ADHD in offspring. The risk was especially elevated for inflammatory bowel diseases (2.4 times the risk) and ankylosing spondylitis (twice the risk).
The presence of any paternal autoimmune diseases was also associated with an elevated risk of ADHD in offspring, although only about half as much as for maternal autoimmune diseases, with a 33% greater risk overall. The association was especially pronounced for psoriasis and ankylosing spondylitis, both doubling the risk of ADHD in offspring.
Meanwhile, half a world away, a joint Swedish, Norwegian, and U.S. team used the Swedish national registries to dig further into these associations. They did this by examining data not only from mothers and fathers, but from full siblings, aunts, uncles, and cousins as well, to probe genetic links.
The team used the Swedish registers to identify 5,178,225 individuals born in Sweden between 1960 and 2010 for whom the identity of the biological mother was known, excluding all who died or emigrated before age 10. They then used the registers to identify the aforementioned relatives.
The researchers only included autoimmune diseases with at least two thousand diagnosed individuals in the cohort, to avoid small sample effects.
They adjusted for sex and year of birth, but not "for another covariate that is often adjusted for (e.g. maternal education, family income, parental psychiatric disorder, parental AD [autoimmune disease] as these are likely not true confounders of the association between ADHD and ADD, but may rather represent either mediator between ADHD and AD's, or proxies of ADHD and/or AD risk or alternatively proxies for the associations we aim to measure."
The team found statistically significant associations between ADHD and autoimmune diseases in all categories of relatives. Mothers of children with ADHD were 29% more likely to have an autoimmune disease than those of typically developing children; fathers were 14% more likely to have an autoimmune disease; full siblings 19% more likely; aunts 12% more likely; uncles 7% more likely; and cousins 4% more likely.
Quantitative genetic modeling produced a significant genetic correlation, but no significant environmental correlation. Genetic correlation explained most, if not all, the covariance between ADHD and any autoimmune disease.
The authors concluded, "ADHD was to some degree more strongly associated with maternal than paternal AD's, but by using aunts and uncles in a genetically informative study design, we demonstrate that this difference cannot be readily explained by AD-mediated maternal effects. Quantitative genetic modeling further indicates that the familial co-aggregation of ADHD and ADs is partly due to shared genetic factors. In addition, biological aunts, uncles, and cousins must be assumed to share the little environment with the index individuals, in further support of shared genetic factors underlying the familial co-aggregation. Moreover, both epidemiological and molecular genetics studies have demonstrated positive genetic correlations between ADHD and ADs, in agreement with our findings."
The authors emphasize that these results do not warrant screening for autoimmune diseases among asymptomatic individuals with ADHD.
Tor-Arne Hegvik, Qi Chen, Ralf Kuja-Halkola, Kari Klungsøyr, Agnieszka Butwicka, Paul Lichtenstein, Catarina Almqvist, Stephen V Faraone, Jan Haavik, Henrik Larsson. "Familial co-aggregation of attention-deficit/hyperactivity disorder and autoimmune diseases: a cohort study based on Swedish population-wide registers," International Journal of epidemiology (2021), published online, https://doi.org/10.1093/ije/dyab151.
Hsuan Lee, Ju-Wei Hsu, Shih-Jen Tsai, Kai-Lin Huang, Ya-MeiBai, Tung-Png Su, Tzeng-Ji Chen, Mu-Hong Chen, "Risk of attention deficit hyperactivity and autism spectrum disorders among the children of parents with autoimmune diseases: a nationwide birth cohort study," European Child &Adolescent Psychiatry (2021), published online, https://doi.org/10.1007/s00787-021-01860-0.
Background:
ADHD treatment includes medication, behavioral therapy, dietary changes, and special education. Stimulants are usually the first choice but may cause side effects like appetite loss and stomach discomfort, leading some to stop using them. Cognitive behavioral therapy (CBT) is effective but not always sufficient on its own. Research is increasingly exploring non-drug options, such as transcranial direct current stimulation (tDCS), which may boost medication effectiveness and improve results.
What is tDCS?
tDCS delivers a weak electric current (1.0–2.0 mA) via scalp electrodes to modulate brain activity, with current flowing from anode to cathode. Anodal stimulation increases neuronal activity, while cathodal stimulation generally inhibits it, though effects vary by region and neural circuitry. The impact of tDCS depends on factors such as current intensity, duration, and electrode shape. It targets cortical areas, often stimulating the dorsolateral prefrontal cortex for ADHD due to its role in cognitive control. Stimulation of the inferior frontal gyrus has also been shown to improve response inhibition, making it another target for ADHD therapy.
There is an ongoing debate about how effective tDCS is for individuals with ADHD. One study found that applying tDCS to the left dorsolateral prefrontal cortex can help reduce impulsivity symptoms in ADHD, whereas another study reported that several sessions of anodic tDCS did not lead to improvements in ADHD symptoms or cognitive abilities.
New Research:
Two recent meta-analyses have searched for a resolution to these conflicting findings. Both included only randomized controlled trials (RCTs) using either sham stimulation or a waitlist for controls.
Each team included seven studies in their respective meta-analyses, three of which appeared in both.
Both Wang et al. (three RCTs totaling 97 participants) and Wen et al. (three RCTs combining 121 participants) reported very large effect size reductions in inattention symptoms from tDCS versus controls. There was only one RCT overlap between them. Wang et al. had moderate to high variation (heterogeneity) in individual study outcomes, whereas Wen et al. had virtually none. There was no indication of publication bias.
Whereas Wen et al.’s same three RCTs found no significant reduction in hyperactivity/impulsivity symptoms, Wang et al. combined five RCTs with 221 total participants and reported a medium effect size reduction in impulsivity symptoms. This time, there was an overlap of two RCTs between the studies. Wen et al. had no heterogeneity, while Wang et al. had moderate heterogeneity. Neither showed signs of publication bias.
Turning to performance-based tasks, Wang et al. reported a medium effect size improvement in attentional performance from tDCS over controls (three RCTs totaling 136 participants), but no improvement in inhibitory control (five RCTs combining 234 persons).
Wang et al. found no significant difference in adverse events (four RCTs combining 161 participants) between tDCS and controls, with no heterogeneity. Wen et al. found no significant difference in dropout rates (4 RCTs totaling 143 individuals), again with no heterogeneity.
Wang et al. concluded, “tDCS may improve impulsive symptoms and inattentive symptoms among ADHD patients without increasing adverse effects, which is critical for clinical practice, especially when considering noninvasive brain stimulation, where patient safety is a key concern.”
Wen et al. further concluded, “Our study supported the use of tDCS for improving the self-reported symptoms of inattention and objective attentional performance in adults diagnosed with ADHD. However, the limited number of available trials hindered a robust investigation into the parameters required for establishing a standard protocol, such as the optimal location of electrode placement and treatment frequency in this setting. Further large-scale double-blind sham-controlled clinical trials that include assessments of self-reported symptoms and performance-based tasks both immediately after interventions and during follow-up periods, as well as comparisons of the efficacy of tDCS targeting different brain locations, are warranted to address these issues.”
The Take-Away:
Previous studies have shown mixed results on the benefits of this therapy on ADHD. These new findings suggest that tDCS may hold some real promise for adults with ADHD. While the technique didn’t meaningfully shift hyperactivity or impulsivity, it was well-tolerated and showed benefit, especially in self-reported symptoms. However, with only a handful of trials to draw from, it would be a mistake to suggest tDCS as a standard treatment protocol. Larger, well-designed studies are the next essential step to clarify where, how, and how often tDCS works best.
Background:
The development of ADHD is strongly associated with functional impairments in the prefrontal cortex, particularly the dorsolateral prefrontal cortex, which plays a key role in maintaining attention and controlling impulses. Moreover, imbalances in neurotransmitters like dopamine and norepinephrine are widely regarded as major neurobiological factors contributing to ADHD.
Executive functions are a group of higher-order cognitive skills that guide thoughts and actions toward goals. “Executive function” refers to three main components: inhibitory control, working memory, and cognitive flexibility. Inhibitory control helps curb impulsive actions to stay on track. Working memory allows temporary storage and manipulation of information for complex tasks. Cognitive flexibility enables switching attention and strategies in varied or demanding situations.
Research shows that about 89% of children with ADHD have specific executive function impairments. These difficulties in attention, self-control, and working memory often result in academic and social issues. Without timely intervention, these issues can lead to emotional disorders like depression, anxiety, and irritability, further affecting both physical health and social development.
Currently, primary treatments for executive function deficits in school-aged children with ADHD include medication and behavioral or psychological therapies, such as Cognitive Behavioral Therapy (CBT). While stimulant medications do improve executive function, not all patients are able to tolerate these medications. Behavioral interventions like neurofeedback provide customized care but show variable effectiveness and require specialized resources, making them hard to sustain. Safer, more practical, and long-lasting treatment options are urgently needed.
Exercise interventions are increasingly recognized as a safe, effective way to improve executive function in children with ADHD. However, systematic studies on school-aged children remain limited.
Moreover, there are two main scoring methods for assessing executive function: positive scoring (higher values mean better performance, such as accuracy) and reverse scoring (lower values mean better performance, such as reaction time). These different methods can affect how results are interpreted and compared across studies. This meta-analysis explored how different measurement and scoring methods might influence results, addressing important gaps in the research.
The Study:
Only randomized controlled trials (RCTs) involving school-aged children (6–13 years old) diagnosed with ADHD by DSM-IV, DSM-5, ICD-10, ICD-11, or the SNAP-IV scale were included. Studies were excluded if the experimental group received non-exercise interventions or exercise combined with other interventions.
Cognitive Flexibility
Using positive scoring, exercise interventions were associated with a narrowly non-significant small effect size improvement relative to controls (eight RCTs, 268 children). Using reverse scoring, however, they were associated with a medium effect size improvement (eleven RCTs, 452 children). Variation (heterogeneity) in individual RCT outcomes was moderate, with no sign of publication bias in both instances.
Inhibitory Control
Using positive scoring, exercise interventions were associated with a medium effect size improvement relative to controls (ten RCTs, 421 children). Using reverse scoring, there was an association with a medium effect size improvement (eight RCTs, 265 children). Heterogeneity was moderate with no sign of publication bias in either case.
Working Memory
Using positive scoring, exercise interventions were associated with a medium effect size improvement relative to controls (six RCTs, 321 children). Using reverse scoring, the exercise was associated with a medium effect size improvement (five RCTs, 143 children). Heterogeneity was low with no indication of publication bias in both instances.
Conclusion:
The team concluded, “Exercise interventions can effectively improve inhibitory control and working memory in school-aged children with ADHD, regardless of whether positive or reverse scoring methods are applied. However, the effects of exercise on cognitive flexibility appear to be limited, with significant improvements observed only under reverse scoring. Moreover, the effects of exercise interventions on inhibitory control, working memory, and cognitive flexibility vary across different measurement paradigms and scoring methods, indicating the importance of considering these methodological differences when interpreting results.”
Although this work is intriguing, it does not show that exercise significantly improves the symptoms of ADHD in children. This means that exercise, although beneficial for many reasons, should not be viewed as a replacement for evidence-based treatments for the disorder.
A recent Wall Street Journal article raised alarms by concluding that many children who start medication for ADHD will later end up on several psychiatric drugs. It’s an emotional topic that will make many parents, teachers, and even doctors worry: “Are we putting kids on a conveyor belt of medications?”
The article seeks to shine a light on the use of more than one psychiatric medication for children with ADHD. My biggest worry about the article is that it presents itself as a scientific study because they analyzed a database. It is not a scientific study. It is a journalistic investigation that does not meet the standards of a scientific report..
The WJS brings attention to several issues that parents and prescribers should think about. It documents that some kids with ADHD are on more than one psychiatric medication, and some are receiving drugs like antipsychotics, which have serious side effects. Is that appropriate? Access to good therapy, careful evaluation, and follow-up care can be lacking, especially for low-income families. Can that be improved? On that level, the article is doing something valuable: it’s shining a spotlight on potential problems.
It is, of course, fine for a journalist to raise questions, but it is not OK for them to pretend that they’ve done a scientific investigation that proves anything. Journalism pretending to be science is both bad science and bad journalism.
Journalism vs. Science: Why Peer Review Matters
Journalists can get big datasets, hire data journalists, and present numbers that look scientific. But consider the differences between Journalism and Science. These types of articles are usually checked by editors and fact-checkers. Their main goals are:
Is this fact basically correct?
Are we being fair?
Are we avoiding legal problems?
But editors are not qualified to evaluate scientific data analysis methods. Scientific reports are evaluated by experts who are not part of the project. They ask tough questions like:
Exactly how did you define ADHD?
How did you handle missing data?
Did you address confounding?
Did you confuse correlation with causation?
If the authors of the study cannot address these and other technical issues, the paper is rejected.
The WSJ article has the veneer of science but lacks its methodology.
Correlation vs. Causation: A Classic Trap
The article’s storyline goes something like this: A kid starts ADHD medication. She has additional problems or side effects caused by the ADHD medications. Because of that, the prescriber adds more drugs. That leads to the patient being put on several drugs. Although it is true that some ADHD youth are on multiple drugs, the WSJ is wrong to conclude that the medications for ADHD cause this to occur. That simply confuses correlation with causation, which only the most naïve scientist would do.
In science, this problem is called confounding. It means other factors (like how severe or complex a child’s condition is) explain the results, not just the thing we’re focused on (medication for ADHD).
The WSJ analyzed a database of prescriptions. They did not survey the prescribers who made the prescriptions of the patients who received them. So they cannot conclude that ADHD medication caused the later prescriptions, or that the later medications were unnecessary or inappropriate.
Other explanations are very likely. It has been well documented that youth with ADHD are at high risk for developing other disorders such as anxiety, depression, and substance use. The kids in the WSJ database might have developed these disorders and needed several medications. A peer-reviewed article in a scientific journal would be expected to adjust for other diagnoses. If that is not possible, as it is in the case of the WSJ’s database, a journal would not allow the author to make strong conclusions about cause-and-effect.
Powerful Stories Don’t Always Mean Typical Stories
The article includes emotional accounts of children who seemed harmed by being put on multiple psychiatric drugs. Strong, emotional stories can make rare events feel common. They also frighten parents and patients, which might lead some to decline appropriate care.
These stories matter. They remind us that each data point is a real person. But these stories are the weakest form of data. They can raise important questions and lead scientists to design definitive studies, but we cannot use them to draw conclusions about the experiences of other patients. These stories serve as a warning about the importance of finding a qualified provider, not as against the use of multiple medications. That decision should be made by the parent or adult patient based on an informed discussion with the prescriber.
Many children and adults with ADHD benefit from multiple medications. The WSJ does not tell those stories, which creates an unbalanced and misleading presentation.
Newspapers frequently publish stories that send the message: “Beware! Doctors are practicing medicine in a way that will harm you and your family.” They then use case studies to prove their point. The title of the article is, itself, emotional clickbait designed to get more readers and advertising revenue. Don’t be confused by such journalistic trickery.
What Should We Conclude?
Here’s a balanced way to read the article. It is true that some patients are prescribed more than one medication for mental health problems. But the article does not tell us whether this prescribing practice is or is not warranted for most patients. I agree that the use of antipsychotic medications needs careful justification and close monitoring. I also agree that patients on multiple medications should be monitored closely to see if some of the medications can be eliminated. Many prescribers do exactly that, but the WSJ did not tell their stories.
It is not appropriate to conclude that ADHD medications typically cause combined pharmacotherapy or to suggest that combined pharmacotherapy is usually bad. The data presented by the WSJ does not adequately address these concerns. It does not prove that medications for ADHD cause dangerous medication cascades.
We have to remember that even when a journalist analyzes data, that is not the same as a peer-reviewed scientific study. Journalism pretending to be science is both bad science and bad journalism.
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