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February 2, 2026
The Background:
Concerns remain about how ADHD and methylphenidate (MPH) use might affect children's health and growth, and especially how it may affect their adult height. While some studies suggest disrupted growth and a possible biological mechanism, the impact of ADHD prevalence and MPH use is still unclear. Children with ADHD may develop unhealthy habits – irregular eating, low physical activity, and poor sleep – that can contribute to obesity and reduced height. MPH’s appetite-suppressing effect can lead to skipped meals or overeating. Since growth hormone is mainly released during deep sleep, chronic sleep deprivation could plausibly slow growth and impair height development; however, a clear link between ADHD, MPH use, overweight, and shorter stature has never been firmly established.
The Study:
South Korea has a single payer health insurance system that covers more than 97% of its population. A Korean research team used the National Health Insurance Service database to perform a nationwide population study to explore this topic further.
The study involved 34,850 children, of whom 12,866 were diagnosed with ADHD. Of these children, 6,816 (53%) had received methylphenidate treatment, while 6,050 (47%) had not. Each patient with ADHD was precisely matched 1:1 by age, sex, and income level to a control participant without ADHD. The sex ratio was comparable in all groups.The team used Body Mass Index (BMI) as an indicator of overweight and obesity.
The Results:
The researchers found that being diagnosed with ADHD was associated with 50% greater odds of being overweight or obese as young adults, and over 70% greater odds of severe obesity (BMI > 30) compared to matched non-ADHD controls, regardless of whether or not they were medicated.
Those diagnosed with ADHD, but not on methylphenidate, had 40% greater odds of being overweight or obese, and over 55% greater odds of becoming severely obese, relative to matched non-ADHD controls.
Methylphenidate users had 60% greater odds of being overweight or obese, and over 85% greater odds of becoming severely obese, relative to matched non-ADHD controls.
There were signs of a dose-response effect. Less than a year’s exposure to methylphenidate was associated with roughly 75% greater odds of becoming severely obese, whereas exposure over a year or more raised the odds 2.3-fold, relative to matched non-ADHD controls. Using MPH increased the prevalence of overweight from 43.2% to 46.5%, with a greater prevalence among those using MPH for more than one year (50.5%).
It is important to note that most of this effect was from ADHD itself, with methylphenidate only assuming a predominant role in severe obesity among those with longer-term exposure to the medicine.
As for height, children with ADHD were no more likely to be short of stature than matched non-ADHD controls. Being prescribed methylphenidate was associated with slightly greater odds (7%) of being short of stature, but there was no dose-response relationship.
Conclusion:
The team concluded, “patients with ADHD, particularly those treated with MPH, had a higher BMI and shorter height at adulthood than individuals without ADHD. Although the observed height difference was clinically small in both sexes and age groups, the findings suggest that long-term MPH exposure may be associated with growth and body composition, highlighting the need for regular monitoring of growth.” They also point out that “Despite these findings, the clinical relevance should be interpreted with caution. In our cohort, the mean difference in height was less than 1 cm (eg, maximum −0.6 cm in females) below commonly accepted thresholds for clinical significance.” Likewise, increases in overweight/BMI were small.
One problem with interpreting the BMI/obesity results is that some of the genetic variants that cause ADHD also cause obesity. If that genetic load increases with severity of ADHD than the results from this study are confounded because those with more severe ADHD are more likely to be treated than those with less severe ADHD.
Due to these small effects along with the many study limitations noted by the authors, these results should be considered alongside the well-established benefits of methylphenidate treatment.
Jihun Song, Sun Jae Park, Jiwon Yu, Jina Chung, Seogsong Jeong, and Sang Min Park, “ADHD and Methylphenidate Use in Prepubertal Children and BMI and Height at Adulthood,” JAMA Network Open (2026), 9(1):e2552019, https://doi.org/10.1001/jamanetworkopen.2025.52019
Noting that “the association between adult ADHD and dementia risk remains a topic of interest because of inconsistent results,” an Israeli study team tracked 109,218 members of a nonprofit Israeli health maintenance organization born between 1933 and 1952 who entered the cohort on January 1, 2003, without an ADHD or dementia diagnosis and were followed up to February 28, 2020.
Israeli law forbids nonprofit HMOs from turning anyone away based on demographic factors, health conditions, or medication needs, thereby limiting sample selection bias.
The estimated prevalence of dementia in this HMO, as diagnosed by geriatricians, neurologists, or psychiatrists, is 6.6%. This closely matches estimates in Western Europe (6.9%) and the United States (6.5%).
The team considered, and adjusted for, numerous covariates: age, sex, socioeconomic status, smoking, depression, obesity, chronic obstructive pulmonary disease, hypertension, atrial fibrillation, heart failure, ischemic heart disease, cerebrovascular disease, diabetes, Parkinson’s disease, traumatic brain injury, migraine, mild cognitive impairment, psychostimulants.
With these adjustments, individuals diagnosed with ADHD were almost three times as likely to be subsequently diagnosed with dementia as those without ADHD. Men with ADHD were two and a half times more likely to be diagnosed with dementia, whereas women with ADHD were over three times more likely, than non-ADHD peers.
More concerning still, persons with ADHD were 5.5 times more likely to be subsequently diagnosed with early onset dementia, as opposed to 2.4 times more likely to be diagnosed with late onset dementia.
On the other hand, the team found no significant difference in rates of dementia between individuals with ADHD who were being treated with stimulant medications and individuals without ADHD. Those with untreated ADHD had three times the rate of dementia. The team nevertheless cautioned, “Due to the underdiagnosis of dementia as well as bidirectional misdiagnosis, this association requires further study before causal inference is plausible.”
Conclusions and Relevance:
This study reinforces existing evidence that adult ADHD is associated with an increased risk of dementia. Notably, the increased risk was not observed in individuals receiving psychostimulant medication, however the mechanism behind this association is not clear.
These findings underscore the importance of reliable ADHD assessment and management in adulthood. They also highlight the need for further study into the link between stimulant medications and the decreased risk of dementia.
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After noting that the association between ADHD and obesity has been called into question because of small sample sizes, wide age ranges, self-reported assessments, and inadequate attention to potential confounders, an Israeli study team set out "to assess the association between board-certified psychiatrist diagnoses of ADHD and measured adolescent BMI [body mass index] in a nationally represented sample of over one million adolescents who were medically evaluated before mandatory military service."
The team distinguished between severe and mild ADHD. It also focused on a single age group.
All Israelis are subject to compulsory military service. In preparation for that service, military physicians perform a thorough medical evaluation. Trained paramedics recorded every conscript's height and weight.
The study cohort was divided into five BMI percentile groups according to the U.S. Centers for Disease Control and Prevention's BMI percentiles for 17-year-olds, and further divided by sex: <5th percentile (underweight), 5th-49th percentile (low-normal), 50th-84th percentile (high normal), 85th-94th percentile (overweight) and ≥95th (obese). Low-normal was used as the reference group.
Adjustments were made for sex, birth year, age at examination, height, country of birth (Israeli or other), socioeconomic status, and education level.
In the fully adjusted results, those with severe ADHD were 32% more likely to be overweight and 84% more likely to be obese than their typically developing peers. Limiting results to Israeli-born conscripts made a no difference.
Male adolescents with mild ADHD were 24% more likely to be overweight, and 42% more likely to be obese. Females with mild ADHD are 33% more likely to be overweight, and 42% more likely to be obese. Again, the country of birth made no difference.
The authors concluded, that both severe and mild ADHD was associated with an increased risk for obesity in adolescents at the age of 17 years. The increasing recognition of the persistence of ADHD into adulthood suggests that this dual morbidity may have a significant impact on the long-term health of individuals with ADHD, thus early preventive measures should be taken.
The Background:
Many studies have tried to determine whether exercise improves executive function in children and adolescents with ADHD, but their conclusions have not always agreed. To bring the evidence together more clearly, the research team re-analyzed the available randomized controlled trials using a statistical approach designed to handle the kinds of data common in this field.
Executive functions are skills that help us control attention and behavior. The three core components are inhibitory control (the ability to stop or override impulses), working memory (holding and manipulating information in mind), and cognitive flexibility (switching between tasks or perspectives). Because a single study often reports multiple tests that tap these different skills, one study can contribute several related results (called effect sizes). Traditional meta-analysis typically treats each effect size as independent; when they are actually correlated, that can bias the combined estimate or force reviewers to discard useful data.
To avoid those problems, the team used a three-level meta-analysis. In this model, variance in the data is separated into three sources:
(1) sampling variance: the random error in each measured effect
(2) within-study variance: differences between multiple effect sizes reported in the same study
(3) between-study variance: differences in effects from one study to another
Accounting for all three levels makes it possible to include every eligible effect size from each study, which preserves information and statistical power and reduces the risk that correlations among effect sizes will overstate results.
The Study:
The review focused on long-term exercise interventions and also tested whether certain factors might change (or moderate) the effects. These potential moderators included participant age, which executive-function subcomponent was measured, the type of exercise, how long each session lasted, the total length of the intervention, and how often sessions occurred.
To be included, studies had to be randomized controlled trials (RCTs) of children or adolescents aged 6–18 diagnosed with ADHD. RCTs randomly assign participants to an intervention or a comparison group and are considered a strong design for testing cause-and-effect. The exercise programs had to be structured and last at least six weeks. Comparison groups varied by study and could include usual care, medication, sedentary activities, health education, waiting lists, or everyday life without the specific exercise program. Fifteen studies including 658 participants met these criteria.
The Results:
The three-level meta-analysis showed that long-term exercise interventions were associated with moderate-to-strong improvements in overall executive function. When statistical outliers were removed, the result remained positive: 13 RCTs with 598 participants showed moderate improvements. In plain terms, this suggests improvements that are noticeable and meaningful on average, not just tiny changes that are unlikely to matter in daily life.
Those moderate gains appeared across all three executive-function domains (inhibitory control, working memory, and cognitive flexibility, meaning the benefits were not limited to a single cognitive skill. The authors also examined exercise type:
“Open-skill” activities, which require reacting to changing situations (for example, many team sports, martial arts sparring, or racket sports), produced moderate-to-large improvements.
“Closed-skill” activities, which are more predictable and repetitive (for example, running or stationary cycling), showed only small, non-significant improvements in this analysis.
The review also found dose-related patterns. Interventions lasting at least twelve weeks were about three times more effective than interventions of six to twelve weeks, and sessions longer than an hour were about twice as effective as shorter sessions. Benefits were largest among adolescents aged 13 and older.
These patterns suggest that longer, more intensive programs, and those that involve open-skill activities, may produce larger gains. However, the authors caution that the overall certainty of the evidence was low. “Low certainty” means that limitations in the available studies (for example, small sample sizes, variability in methods, or possible bias) make it difficult to be confident that the observed effects will hold up exactly the same way in future research. Some subgroup findings (age, intervention duration, and others) were based on only a small number of effect sizes, so those moderator results should be treated as exploratory rather than definitive.
The Take-Away:
In short, this three-level meta-analysis suggests that regular, structured exercise (particularly longer programs and open-skill activities) may help improve executive functions in children and adolescents with ADHD. The evidence is promising but not yet strong enough to be considered conclusive, and the authors recommend more, larger randomized trials to confirm specifically which types and doses of exercise are most effective. Moreover, neither this meta-analysis or others show that exercise can replace standard treatments for reducing the core symptoms of ADHD (inattention, hyperactivity, impulsivity).
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When a patient sits down in an examination room today, their physician is rarely the first voice they have heard regarding their symptoms. More often, an algorithm got there first.
According to a nationwide survey by The Physicians Foundation conducted with Medscape, medical misinformation is no longer a peripheral nuisance; it is a daily clinical crisis. Nearly all surveyed physicians (99.9%) reported that their patients had been influenced by medical misinformation over the past year.
While misinformation affects every discipline from oncology to cardiology, few conditions sit as squarely in the algorithmic crosshairs as ADHD. From viral 30-second video clips trivializing complex executive dysfunction to predatory wellness campaigns attacking evidence-based medications, the attack on evidence directly threatens the well-being of children and adults living with ADHD.
Key Findings from The Physicians Foundation
The survey, which captured perspectives from over 1,000 practicing physicians, paints a sobering picture of how unverified information disrupts modern medicine:
The challenge is especially acute in communities already facing systemic healthcare hurdles:
As the survey illustrates, 38% of rural physicians encounter "a great deal" of health misinformation, far exceeding their suburban (21%) and urban (25%) peers. In rural and underserved regions, where access to developmental pediatricians and psychiatrists is already scarce, online narratives frequently fill the void left by provider shortages.
Why ADHD Is Ground Zero for Health Misinformation
Despite decades of neurobiological research confirming its validity, ADHD remains uniquely vulnerable to digital distortions in three distinct ways:
1. The Dueling Traps: "Life Hack" Trivialization vs. Denialism
Social media platforms host billions of views under ADHD-related tags. While digital awareness has helped destigmatize mental health, it frequently collapses nuanced clinical criteria into broad, relatable personality traits such as zoning out during a boring meeting, misplacing keys, or feeling restless.
This creates two opposing misinformation hazards:
2. Medication Stigma and Treatment Nonadherence
The survey found that 49% of doctors frequently encounter medication nonadherence and 45% face treatment refusal due to misinformation.
In ADHD care, this finding is acutely visible around stimulant pharmacotherapy. First-line stimulant medications have high response rates and extensive safety profiles spanning decades. Yet online narratives persistently frame them as dangerous narcotics, accusing parents of "drugging their children" or claiming medications permanently alter a child's brain.
Terrified parents frequently delay initiating care or discontinue effective regimens without clinical oversight, turning instead to unproven, expensive alternative supplements, unverified nootropics, or restrictive elimination diets.
3. Escalating Anxiety and Parental Guilt
With 66% of physicians observing increased patient anxiety driven by online health claims, the emotional toll on families cannot be overstated. Parents of newly diagnosed children are inundated with contradictory advice: one post warns that failing to medicate guarantees academic failure, while another claims that medicating guarantees addiction.
Adults navigating a new diagnosis experience similar distress, second-guessing their lived experiences and feeling deep shame over their executive dysfunction.
4. The 15-Minute Primary Care Bottleneck
Because pediatricians and family physicians handle most ADHD diagnoses and management, the survey’s warning that 70% of primary care providers feel hamstrung by misinformation hits ADHD patients first.
Deconstructing a viral video, explaining the difference between therapeutic stimulant dosing and substance misuse, and addressing years of internalized stigma takes time. In a standard 15-to-20-minute primary care visit, providers are forced to choose between rushing through diagnostic assessments or leaving patients' misinformed fears unaddressed.
Rebuilding the Partnership: Steps for Patients, Families, and Providers
Addressing the erosion of trust requires practical, collaborative shifts from both sides of the examination table:
For Patients and Caregivers
For Healthcare Providers and Systems
Medical misinformation thrives in the gap between a patient's vulnerability and the clinical system's time constraints. By recognizing how digital noise distorts ADHD, patients and clinicians can work together to replace viral anxiety with evidence-based care.
The Background:
Adults with ADHD often struggle more at work than their peers without ADHD. They tend to underperform on job tasks, advance less in their careers, miss more workdays, and face higher rates of unemployment. Research from several countries, including Japan, points to two main channels through which ADHD erodes workplace productivity: absenteeism, or missing work entirely, and presenteeism, showing up but performing below one’s usual capacity. Both problems typically trace back to ADHD’s core symptoms: difficulty sustaining attention, managing time, staying organized, and navigating relationships with coworkers and supervisors.
Stigma compounds these challenges. Employers and the public often have limited understanding of how ADHD manifests in adults, which can translate into unfair treatment or diminished job opportunities. That fear of judgment, in turn, discourages some people from seeking a psychiatric evaluation in the first place, delaying diagnosis and treatment, and with it, delaying access to support that could improve both their work performance and daily functioning.
Japan does offer medical care and workplace support for adults with ADHD. Options include social skills training, which teaches practical strategies for communication and collaboration; self-reliance support programs that help with daily living and job management; and, in more severe cases, a disability pension for those unable to work. Still, it remains unclear whether these employment-support services are robust enough to help people who want to work actually secure and hold onto steady jobs.
The impact of ADHD extends beyond the individual diagnosed. Supporting a family member with ADHD can be emotionally and logistically demanding, often cutting into a caregiver’s own capacity to work and earn, meaning that the economic toll of ADHD ripples outward.
The Research:
Most prior research on the economic costs of ADHD, in both children and adults, has come from the United States and Europe, focusing on medical expenses, lost productivity, and social support spending. Until recently, no one had attempted a comparable estimate for adult ADHD in Japan or elsewhere in Asia.
To address that gap, a Japanese research team conducted a cross-sectional observational study (meaning they gathered data at a single point in time and examined existing patterns rather than testing an intervention). They drew on three sources: a retrospective review of medical insurance claims, a web-based survey of affected individuals, and official government statistics. Combining these, they estimated annual costs from a societal perspective, accounting for medical expenses, lost work productivity, and government welfare spending, as well as productivity losses among family caregivers.
The claims analysis relied on JMDC, a nationwide database of insurance receipts and medical examination records spanning multiple health insurers and covering 14 million residents. Within it, the researchers identified 30,730 adult outpatients diagnosed with ADHD.
The Results:
Annual medical costs per adult with ADHD (combining outpatient visits and medication) averaged 284,000 yen (about $1,750). Scaling this figure to match the age and sex distribution of Japan’s adult population produced a nationwide estimate of 74 billion yen (about $455 million).
A separate web-based survey found that, after statistical matching, nearly half of adults with ADHD received a disability pension, yielding a nationwide estimate of 95 billion yen (about $585 million) in ADHD-related pension payments. Including public employment support services, total social welfare spending reached 390 billion yen (about $2.4 billion).
Workplace productivity losses were substantial as well. With an unemployment rate more than four percentage points higher than the general population, unemployment-related losses among adults with ADHD totaled an estimated 50 billion yen. Lower average incomes among those employed accounted for a further 315 billion yen. Once absenteeism and presenteeism were factored in, total productivity losses reached 570 billion yen (about $3.5 billion).
Family members bore a comparable burden: productivity losses among adult relatives of people with ADHD were estimated at 540 billion yen (about $3.3 billion).
Taken together, these figures point to a nationwide socioeconomic burden of 1.6 trillion yen (roughly $11 billion), equivalent to nearly $30,000 per adult with ADHD.
The Take-Away:
“This study, the first estimate of the annual socioeconomic burden of adult ADHD in Japan, underscores the necessity of providing appropriate support to adult patients with ADHD and their families and the prevention of comorbidities,” the research team concluded. “In particular, measures to support participation in the workplace to improve patients’ quality of life and reduce the social and economic burden should be explored. Furthermore, it is hoped that estimating the annual socioeconomic burden of adult ADHD will help clarify policy priorities in Japan.”
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