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Noting that “evidence on the association between ADHD and a physical condition associated with obesity, namely type 2 diabetes mellitus (T2D), is sparse and has not been meta-analysed yet,” a European study team performed a systematic search of the peer-reviewed medical literature followed by a meta-analysis, and then a nationwide population study.
Unlike type 1 diabetes, which is an auto-immune disease, type 2 diabetes is believed to be primarily related to lifestyle, associated with insufficient exercise, overconsumption of highly processed foods, and especially with large amounts of refined sugar. This leads to insulin resistance and excessively high blood glucose levels that damage the body and greatly lower life expectancy.
Because difficulty with impulse control is a symptom of ADHD, one might hypothesize that individuals with ADHD would be more likely to develop type-2 diabetes.
The meta-analysis of four cohort studies encompassing more than 5.7 million persons of all ages spread over three continents (in the U.S., Taiwan, and Sweden) seemed to point in that direction. It found that individuals with ADHD had more than twice the odds of developing type 2 diabetes than normally developing peers. There was no sign of publication bias, but between-study variability (heterogeneity) was moderately high.
The nationwide population study of over 4.2 million Swedish adults came up with the same result when adjusting only for sex and birth year.
Within the Swedish cohort there were 1.3 million families with at least two full siblings. Comparisons among siblings with and without ADHD again showed those with ADHD having more than twice the odds of developing type 2 diabetes. That indicated there was little in the way of familial confounding.
However, further adjusting for education, psychiatric comorbidity, and antipsychotic drugs dropped those higher odds among those with ADHD in the overall population to negligible (13% higher) and barely significant levels.
The drops were particularly pronounced for psychiatric comorbidities, especially anxiety, depression, and substance use disorders, all of which had equal impacts.
The authors concluded, “This study revealed a significant association between ADHD and T2D [type 2 diabetes] that was largely due to psychiatric comorbidities, in particular SUD [substance use disorders], depression, and anxiety. Our findings suggest that clinicians need to be aware of the increased risk of developing T2D in individuals with ADHD and that psychiatric comorbidities may be the main driver of this association. Appropriate identification and treatment of these psychiatric comorbidities may reduce the risk for developing T2D in ADHD, together with efforts to intervene on other modifiable T2D risk factors (e.g., unhealthy lifestyle habits and use of antipsychotics, which are common in ADHD), and to devise individual programs to increase physical activity. Considering the significant economic burden of ADHD and T2D, a better understanding of this relationship is essential for targeted interventions or prevention programs with the potential for a positive impact on both public health and the lives of persons living with ADHD.”
Miguel Garcia-Argibay, Lin Li, Ebba Du Rietz, Le Zhang, Honghui Yao, Johan Jendle, Josep A. Ramos-Quiroga, Marta Ribasés, Zheng Chang, Isabell Brikell, Samuele Cortese, Henrik Larsson, “In utero exposure to ADHD medication and long-term offspring outcomes,” Neuroscience and Biobehavioral Reviews (2023), 147:105076, https://doi.org/10.1016/j.neubiorev.2023.105076.
Thanks to improvements in cancer treatment, there is a growing population of childhood and adolescent cancer survivors (CACSs). CACSs are at an increased risk of chronic physical, psychological, and social problems because of their cancer experiences and intensive cancer treatments. These include depression, anxiety, suicidal ideation, and post-traumatic stress disorder (PTSD).
To what extent, if at all, does this also apply to ADHD? Noting that “previous studies … have reported inconsistent findings,” a local research team took advantage of Taiwan’s mandatory single-payer National Health Insurance that covers over 99% of the island’s population. More specifically, the National Health Insurance Research Database (NHIRD) maintains data on the insured population available on formal request for study purposes.
Linking the catastrophic illness database, mental disorders database, and longitudinal health insurance database, they tracked children age younger than 10 years and adolescents aged 11-17 years who were diagnosed with any malignancy (cancer) between 2002 and 2011 with no history of major psychiatric disorders (including ADHD). Parental history of major psychiatric disorders was likewise controlled as a potential confounder.
The team identified 5,121 CACSs, which they matched one to ten with 51,210 age-, sex-, income-, and residence-matched cancer-free controls.
ADHD diagnoses were made by board-certified psychiatrists during the study follow-up period (from enrollment through 2011) based on a comprehensive clinical interview and clinical judgment.
Cancer survivors were diagnosed with ADHD at more than six times the rate of matched controls. Survival duration made no significant difference in this outcome.
Cancers of bone, connective tissue, skin, and breast were associated with a more than threefold increase in risk of an ADHD diagnosis. For cancers of the circulatory system, there was a more than sixfold increased risk of ADHD, and for those of the genitourinary organs, more than sevenfold increased risk.
For brain cancer survivors, the increased risk of ADHD was more than twelvefold. That may be at least in part because the brain itself was targeted for treatment in these instances, which plausibly could cause damage resulting in psychiatric disorders.
The team concluded, “we observed a comparatively higher risk of MPDs [major psychiatric disorders] among CACSs than among controls and likewise found that such risks varied across different cancer types. Survivors of both CNS [central nervous system] and non-CNS cancers have increased risks of MPD diagnoses. Among the enrolled CACSs, ASD [autism spectrum disorder] and ADHD were associated with most types/categories of cancers. Long-term care of this vulnerable population must include psychosocial interventions for patients and their families. Physicians need to be aware of early signs of mental health problems in this high-risk subpopulation and arrange early interventions accordingly.”
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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