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January 9, 2024
A commonly reported risk associated with ADHD medication is reduced growth in height. But studies to date have generally not adequately described or measured possible confounders, such as genetic factors, prenatal factors, or socioeconomic factors. What if ADHD were associated with reduced height even in the absence of medications?
An international study team explored this question by performing a nationwide population study comparing data from before (1968-1991) and after (1992-2020) the adoption of stimulant therapy for ADHD in Sweden.
The country’s single-payer health insurance system that connects patient records with all other national registers through unique personal identification numbers makes such analysis possible. Sweden also has military service conscription, which records the heights of 18-year-old males.
The participants were all 14,268 Swedish males with a diagnosis of ADHD who were drafted into military service at any time from 1968 through 2020.
Up to five non-ADHD controls were identified for each ADHD case, matched by sex (they had to be male), birth year, and county. The total number of controls was 71,339.
Among 34,586 participants in the period before adoption of stimulant medications (1968-1991), those diagnosed with ADHD had roughly 30% greater odds of being shorter than normal (166-172 vs. 173-185 cm) than typically developing controls. That dropped to 20% greater odds among the 34,714 participants in the cohort following adoption of stimulant medications.
The odds of those diagnosed with ADHD being much shorter than normal (150-165 vs. 173-185 cm) remained identical (about 55% greater) among the almost 30,000 participants in both cohorts.
In other words, there was no increase in the odds of ADHD individuals being shorter than normal after adoption of stimulant therapy in Sweden compared with before such adoption.
Furthermore, after adjusting for known confounders, including birth weight, inflammatory bowel disease, celiac disease, hypothyroidism, anxiety disorders, depression, substance use disorder, and highest parental education, the odds of those diagnosed with ADHD being shorter than normal or much shorter than normal in the 1992-2020 cohort dropped to roughly 10% and 30% greater, respectively.
Could it be the disorder itself rather than stimulant treatment that is associated with reduced height in individuals diagnosed with ADHD?
To address effects of environmental and familial/genetic confounding, the team then compared the entire cohort of males diagnosed with ADHD from 1968 through 2020 with typically developing male relatives, ranging from first cousins to full siblings.
Among full siblings, the odds of those with ADHD diagnoses being shorter (over 90,000 participants) or much shorter (over 77,000 participants) were a statistically significant 14% and 18%, respectively.
The authors concluded, “Our findings suggest that ADHD is associated with shorter height. On a population level, this association was present both before and after ADHD-medications were available in Sweden. The association between ADHD and height was partly explained by prenatal factors, psychiatric comorbidity, low SES [socioeconomic status] and a shared familial liability for ADHD.”
Rickard Ahlberg, Miguel Garcia-Argibay, Ebba Du Rietz, Agnieszka Butwicka, Samuele Cortese, Brian M. D’Onofrio, Jonas F. Ludvigsson, and Henrik Larsson, “Associations Between Attention-Deficit/Hyperactivity Disorder (ADHD), ADHD Medication and Shorter Height: A Quasi-Experimental and Family-based Study,” Journal of the American Academy of Child & Adolescent Psychiatry (2023), https://doi.org/10.1016/j.jaac.2023.03.015.
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.
Oppositional Defiant Disorder (ODD)—a pattern of chronic irritability, anger, arguing, or defiance—is one of the most challenging behavioral conditions families and clinicians face.
A new study involving 2,400 children ages 3–17 offers one of the clearest pictures yet. Using parent-reported data from the Pediatric Behavior Scale, researchers compared how often ODD appears in Autism spectrum disorder (ASD), ADHD-Combined presentation (ADHD-C), ADHD-Inattentive presentation (ADHD-I), and those with both ASD and ADHD.
Results:
Children with ADHD-Combined presentation show both hyperactivity/impulsivity and inattention. They had the highest ODD rates of any single diagnosis: 53% of kids with ADHD-Combined met criteria for ODD.
But when autism was added to ADHD-Combined, the prevalence jumped to 62%. This group also had the highest overall ODD scores, suggesting more severe or more impairing symptoms.
This synergy matters: while autism alone increases ODD risk, the presence of ADHD-Combined is what pushes prevalence into the majority range. Other groups showed lower, but still significant, rates of ODD:
These findings echo what clinicians often see: children with inattentive ADHD, while struggling significantly with attention and learning, tend to show fewer behavioral conflict patterns than those with hyperactive/impulsive symptoms.
It is important to note that ODD is considered to have two main components. Across all diagnostic groups, ODD consistently broke down into these two components: either Irritable/Angry (emotion-based) or Oppositional/Defiant (behavior-based). But the balance between these components differed depending on diagnosis. Notably, Autism + ADHD-Combined showed higher levels of the irritable/angry component than ADHD-Combined alone. The oppositional/defiant component did not differ much between groups. This suggests that autism elevates the emotional side of ODD more than the behavioral side, which is important for clinicians to note before tailoring interventions.
The study notes that autism, ADHD, and ODD often cluster together, with 55–90% comorbidity in some combinations.
As the authors explain, “The high co-occurrence of ADHD-Combined in autism (80% in our study) largely explains the high prevalence of ODD in autism.”
Clinical Implications: Why This Study Matters
The researchers point to a straightforward recommendation: clinicians shouldn’t evaluate these conditions in isolation. A child referred for autism concerns might also be struggling with ADHD. A child referred for ADHD might have undiagnosed ODD. And ignoring one disorder can undermine treatment for the others.
Evidence-based interventions (behavioral therapy, parent training, school supports, and/or medication) can reduce symptoms across all three diagnoses while improving long-term outcomes, including overall quality of life.
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