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August 28, 2026
The Background:
Motor vehicle crashes remain one of the most significant public health challenges in the United States. In 2022 alone, nearly 44,000 people died on American roads, and more than 2.6 million crash-related injuries required emergency care. Most people are familiar with the usual suspects: drunk driving, speeding, and distracted driving from phones. These risks are well-documented and the focus of ongoing public safety campaigns.
But a serious risk factor has been flying under the radar: untreated ADHD. Despite receiving little attention from the public, policymakers, or transportation safety agencies, it may belong in the same conversation as these better-known dangers.
ADHD is not currently recognized by the National Highway Traffic Safety Administration as a driving risk factor; yet inattention and impulsivity, two of its defining features, are consistently cited as common contributors to crashes. Beyond these core symptoms, adults with ADHD may also experience emotional dysregulation, which can further impair driving behavior.
The Research:
Prior studies on ADHD and crash risk have produced estimates ranging from a 5% to a 70% increase. This massive heterogeneity has made it difficult to draw firm conclusions. This new meta-analysis set out to offer some clarity on these numbers.
Researchers focused specifically on adults aged 18 to 65 with a formal ADHD diagnosis who were not receiving treatment, comparing them to controls without ADHD. Four studies met these criteria, collectively covering more than 2.75 million people.
The Results:
The findings were striking: untreated ADHD was associated with a 93% increase in crash risk (95% confidence interval: 88%–99%). There was no evidence of publication bias. Although there was meaningful variation across studies, most of it stemmed from the smallest study (just 36 participants) which reported an outlier estimate of a 16-fold increase.
To put the 93% figure in context: a separate meta-analysis found that alcohol use is associated with a 150% increase in crash risk. Another way to understand just how significant this risk really is, untreated ADHD raises crash risk by more than half as much as alcohol does.
The analysis also found a dose-response relationship between ADHD symptom severity and crash risk: each incremental increase in symptom severity corresponded to a 5–6% higher crash risk. At the highest severity levels, crash risk approached that associated with alcohol use. This gradient reinforces that we're not looking at a binary distinction between “has ADHD” and “doesn’t” — the worse the symptoms, the greater the danger on the road.
The Takeaway:
These findings have practical implications for patients, families, clinicians, and policymakers alike. Untreated ADHD is not a minor footnote in the driving safety literature; rather, it is a substantial, measurable, and potentially modifiable risk factor. The question of whether and how it should be factored into licensing policy, clinical practice, and public health messaging deserves serious attention.
Ann Childress, Hirah Malik, and Jim Potenziano, “The Impact of Untreated Attention‑Deficit/Hyperactivity Disorder on Motor Vehicle Accidents: A Systematic Review and Meta‑Analysis,” Advances in Therapy (2026), published online, https://doi.org/10.1007/s12325-026-03638-9.
Taiwan has a single-payer healthcare system that covers virtually every inhabitant (99.5%). That makes it relatively easy to track healthcare issues using its comprehensive National Health Insurance Research Database.
This database maintains a subset, the Longitudinal Health Insurance Database (LHID), consisting of a million persons, with no significant differences in sex, age, or healthcare use from the parent database.
A Taiwanese research team used the LHID to identify 114,486 individuals diagnosed with ADHD from 1997 to 2013. It then compared their motor vehicle (including motorcycles, which are extremely common in Taiwan) crash patterns with 338,261 normally developing controls from the same database.
Adjusting for sex, age, and psychiatric comorbidities, persons with ADHD were about a fifth (19%)more likely to be in traffic crashes. Breaking it down further by sex, women with ADHD were no more likely to be in crashes, but men with ADHD were about a quarter (24%) more likely than their healthy counterparts.
Since the database also tracks pharmaceutical prescriptions, the team also looked into the effect of methylphenidate (MPH), the medication that is the first-line treatment for ADHD under Taiwanese guidelines, and the only approved stimulant. Atomoxetine, a non-stimulant, is used where MPH is either ineffective or not indicated for any other reason and is only used in 4% of all cases.
Of the 114,486 persons diagnosed with ADHD, 89,826 used MPH, and 24,660 did not.
Compared with persons with ADHD who were not on methylphenidate, those with ADHD who were on MPH for 180 days (roughly half a year) or less had 77% fewer accidents, and those on MPH for over 180 days had 93% fewer accidents. This strong dose-response relationship is suggestive of a causal relationship, with MPH perhaps reducing impulsive behavior, particularly among young men with ADHD.
The team also conducted within-person analyses, comparing times when persons with ADHD were taking MPH with periods when they were not. These showed no effect within 30 days of use, rising to a 65%reduction in crashes within 60 to 90 days of use, which was barely outside the 95% confidence interval (p = .07), very likely because of "the extremely low incidence of transport accidence (i.e. 0.6%)enlarged the confidence interval."
The authors concluded, "All registration medical claim data came from the nationally-representative sample of NHI, minimizing the selection and recall bias. By excluding transport accidents before ADHD diagnosis, we have precluded the reverse association between ADHD and road traffic accidents as much as possible. The advantage of the between-subjects comparison was that we were able to examine the MPH effect in different dose groups. However, confounding by indication cannot be eliminated. For example, those with a severe degree of ADHD symptoms, an exhibition of risky behaviors, or comorbid with other psychiatric illnesses were more likely to be prescribed medication. Hence, we also performed within-subject comparisons to adjust for time-invariant factors."
Transport safety thus offers another compelling reason to treat ADHD symptoms. Methylphenidate in particular seems to be especially effective in reducing traffic fatalities and injuries.
Children with ADHD are at higher risk of getting severe burns than normally-developing children. Burn injuries can be traumatic, imposing physical, psychological, and economic burdens on children, their families, and society. Methylphenidate is known to be effective in reducing ADHD symptoms. Can it also reduce the risk of burn injuries?
A team of Taiwanese researchers collaborating with two British researchers explored that question by looking at a nationwide population cohort. Taiwan has a single-payer national health insurance system that includes the entire population (99.6 percent coverage). Using Taiwan's National Health Insurance Research Database(NHIRD), they identified over 90,000 youths under 18 years old with a diagnosis of ADHD. Youths who had burned injuries before diagnosis were excluded. ADHD youths were further divided into three groups: those not prescribed methylphenidate (over 22,000), those prescribed methylphenidate for less than 90 days (over 17,500), and those prescribed methylphenidates for 90 days or more(over 50,000).
Because methylphenidate is the only approved stimulant in Taiwan, it was the only stimulant analyzed in this study. Atomoxetine, a non-stimulant, is also approved in Taiwan, but only for those whose, outcomes with methylphenidate are suboptimal. It was only used by 4 percent of those on ADHD medication, and generally after prior use of methylphenidate, so there was no way to evaluate its effectiveness. Among ADHD youths not on methylphenidate, the proportion who got burn injuries was 6.7 percent. That dropped to 4.5 percent for those medicated for under 90 days, and to 2.9 percent for those on longer-term medication.
Calculations indicated that half of all burn injuries could have been prevented if all youths had been on methylphenidate. After adjusting for multiple confounders - seizure, intellectual disability, autism, conduct disorder, opposition defiant disorder, anxiety, depression, and psychotropic use (benzodiazepine, Z-drugs, antipsychotics, and antidepressants) that taking methylphenidate for any length of time was 38 percent less likely to suffer burn injuries. Moreover, longer-term medication had a greater beneficial effect. Those taking methylphenidate for under 90 days were 30 percent less likely to get burn injuries, whereas those taking it for 90 or more days were less than half as likely to get burn injuries as those not on methylphenidate.
The authors emphasized, "This nationwide population-based study has several strengths. First, the nationally representative sample was substantial and minimized selection bias. Second, patients with ADHD were identified through physician-based diagnoses. Third, all MPH [methylphenidate] prescriptions are recorded in the NHIRD, avoiding misclassification bias. Also, by excluding burn injuries before ADHD diagnosis, the reverse causal relationship between ADHD and burn injury was eliminated."
Most previous studies of suicide and self-harm risk among persons with ADHD have focused on adolescents and adults. They’ve also tended to be cross-sectional, analyzing data from a population at a specific point in time.
An Australian study team took a different approach, conducting a before-and-after study through the birth cohort of the Longitudinal Study of Australian Children (LSAC), comprising 5,107 children who have been followed up every two years since birth.
The diagnosis of ADHD was based on parents reporting that their child had received a diagnosis of ADHD at or before age ten.
Suicide and self-harm were defined as children’s self-report at age 14 of any thought or attempt of suicide and self-harm respectively over the past year.
The team adjusted for the following confounders: socioeconomic status, birth weight, ADHD medication history, maternal education level, maternal age at birth, experience in bullying victimization at age 12, and depression score based on Short Mood and Feelings Questionnaire (SMFQ).
Of the 5,107 participants, 3,696 had all the valid data required for analysis and were included in the final cohort. Of these, 3.6% were diagnosed with ADHD by age 10.
With diagnosis of ADHD at age 10 and all other factors held constant:
Both depression and exposure to bullying were statistically significant mediators for the relationship. Nevertheless, depression and exposure to bullying each accounted for well under 10% of the overall effect.
Neither socioeconomic status nor maternal factors had any significant mediating effect on outcomes.
Conclusion:
The authors concluded, “This study provides compelling evidence that children diagnosed with ADHD at the age of 10 years face significantly elevated risks of experiencing suicidal thoughts, planning, or attempts, as well as self-harm, by the age of 14 years, which underscores the critical importance of recognizing and addressing these heightened risks in children with ADHD.”
While factors like depression and bullying contribute, ADHD itself remains a key risk factor. Early intervention and strong mental health support are crucial to protecting these children’s well-being.
The Background:
Dementia is a rapidly growing public health problem affecting more than 50 million people worldwide. Nearly 10 million new cases are diagnosed each year, and that number is expected to almost triple by 2050. The most common form is Alzheimer’s disease, accounting for roughly 60–70% of cases, followed by vascular dementia at around 20%. Other types include dementia with Lewy bodies, Parkinson’s disease dementia, and frontotemporal dementia. While no cure exists, managing modifiable risk factors (such as high blood pressure, smoking, physical inactivity, and poorly controlled diabetes) can delay or slow both the onset and progression of the condition.
Several studies have reported an elevated dementia risk among people with ADHD, and a number of mechanisms may explain this association. These include shared genetic or neurobiological vulnerabilities, reduced cognitive reserve (leaving the brain less resilient to age-related damage), and greater lifetime exposure to other established dementia risk factors.
Earlier reviews explored the possible link between ADHD and dementia, but tended toward a broader scope (incorporating other neurodegenerative disorders or mixing study designs), which introduced substantial variability and precluded quantitative synthesis. The relevant research literature has also expanded considerably since those reviews appeared.
The Study:
This meta-analysis restricted inclusion to case-control and cohort studies, yielding five that met the criteria. One was a case-control study with 400 participants; the other four were cohort studies collectively covering 3.7 million individuals, two retrospective and two prospective.
The Results:
Pooling the four cohort studies, individuals with ADHD showed approximately two-and-a-half times the dementia risk of those without the diagnosis. There was no indication of publication bias.
The Take-Away:
The authors concluded that ADHD is associated with a significantly increased risk of all-cause dementia in later life, while noting that its relationship to specific dementia subtypes remains less clear and warrants attention in future research.
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The Background:
Women with polycystic ovary syndrome (PCOS) themselves show higher rates of ADHD. Because ADHD is partly heritable (meaning genes contribute to the condition), some of the increased ADHD seen in children of mothers with PCOS could come from shared genetic factors. In other words, a mother’s and her child’s increased risk might sometimes reflect common genes rather than an effect of the pregnancy itself.
Beyond genetics, growing evidence points to maternal metabolic problems during pregnancy as another important risk factor for neurodevelopmental outcomes. PCOS is one of these conditions and is considered both potentially modifiable (treatable or manageable) and biologically plausible as a contributor to risk. PCOS affects an estimated 5–10% of women of reproductive age worldwide and is characterized by signs such as hyperandrogenism (higher-than-normal levels of “male” hormones), insulin resistance (poorer ability to use the hormone insulin, which can affect blood sugar and metabolism), and chronic low-grade inflammation.
However, studies to date have not all reached the same conclusions. Some research suggests the association between maternal PCOS and offspring ADHD is stronger for girls, while other studies did not analyze results by child sex. Methodological differences make it harder to draw clear conclusions.
The Study:
It’s important to note that the studies included in this meta-analysis were observational (cohort studies and case-control studies). Observational studies can identify associations (that two things occur together) but cannot prove that one causes the other. A cohort study follows people over time, and a case-control study compares people with a condition to similar people without it.
The pooled results came from six studies that together included almost 1.4 million mother–child pairs and that adjusted for confounders (other factors that might influence the result, such as maternal age or socioeconomic status). After statistical adjustment, children of mothers with PCOS had about 40% greater odds of ADHD than children of mothers without PCOS. The analysis reported no evidence of publication bias (no clear sign that only positive studies were published) and zero heterogeneity (the results were consistent across the studies).
There was no meaningful difference in results between cohort and case-control studies, and the meta-analysis did not find a significant difference in the association when comparing male and female offspring.
The Take-Away:
The research team concluded that this large-scale synthesis found an association between maternal PCOS and higher odds of ADHD and other neuropsychiatric conditions in children. They suggested that children born to mothers with PCOS may benefit from developmental monitoring to identify and address problems early, while emphasizing that causal relationships have not been established. They called for further studies to confirm these findings and to investigate the biological and environmental mechanisms that might explain the association. Indeed, because women with PCOS show higher rates of ADHD than other women, we need genetically informed research designs to see if the reported association is confounded.
The Background:
Food insecurity is a widespread public‑health problem. Food insecurity refers to limited or uncertain access to enough safe, nutritious food. This term is used to describe households that sometimes or often can’t afford enough food or can only buy cheaper, less‑healthy options.
In the United States, almost eleven million children and teens (14%) lived in food‑insecure households in 2019. By 2023, the share of households with food‑insecure children and adolescents was estimated to have risen to about 18%.
Food insecurity is linked to worse physical health in children, including conditions like anemia (low red‑blood‑cell count), asthma, and delays in physical or mental development. It is also associated with problems in thinking and conduct (for example, aggressive behavior, anxiety, depression, and trouble concentrating or sitting still).
Those thinking and behavior problems can look a lot like ADHD (persistent patterns of inattention, hyperactivity, and impulsivity. This can make it hard for clinicians to tell whether symptoms come from ADHD itself, from the stress of poverty and food insecurity, or a mix of both. That overlap can complicate diagnosis and sometimes lead to misdiagnosis.
Smaller recent studies have looked at mental‑health links and found higher odds of ADHD and other mental‑health conditions among food‑insecure children aged 5–11 years. In one set of findings, moderate food insecurity was associated with 50% greater odds of an ADHD diagnosis and severe food insecurity with about 67% greater odds relative to food‑secure children.
The Study:
Because many past studies looked at single risk factors or only measured symptom severity, fewer investigations have focused specifically on household food insecurity as it relates to actual ADHD diagnoses and how that might matter for care. To address that gap, researchers used multiple years (2016–2022) of data from the U.S. National Survey of Children’s Health (NSCH). This survey is designed to be nationally representative and asks parents about their child’s health, including whether a doctor or other clinician has diagnosed ADHD.
The study included 232,571 children and adolescents (ages 3–17) and used statistical methods to adjust for other factors that could affect ADHD risk. Those factors included the child’s sex and race/ethnicity; the mother’s age; family income expressed as a percentage of the federal poverty level (a government measure used to classify income groups); the highest level of parent education; adverse childhood experiences (such as exposure to abuse, household substance use, or parental separation); birthweight (for example, low birthweight); and not getting enough sleep. Adjusting for these variables helps isolate the association between food insecurity and ADHD, though it cannot prove cause and effect.
The Results:
In this large, nationally representative sample, the researchers found a clear dose–response relationship: as the level of household food insecurity increased, so did the odds of a child having a clinician‑diagnosed ADHD (as reported by parents). In other words, greater food insecurity was linked to a higher likelihood of ADHD.
Compared with children in households that “could always afford to eat good, nutritious meals” (the reference group), the study found the following increases in odds of ADHD: children in households that “could always afford enough to eat but not always the kinds of food we should eat” had about 30% greater odds; children in households that sometimes “could not afford enough to eat” had about 55% greater odds; and children in households that often “could not afford enough to eat” had about 80% greater odds. (Saying “30% greater odds,” etc., means the odds were 1.30, 1.55, and 1.80 times those of the reference group, respectively — this describes a relative increase, not the absolute percentage of children with ADHD.)
The Take-Away:
The authors conclude that household food insecurity was associated with higher odds of parent‑reported clinician‑diagnosed ADHD in a dose‑response pattern. They suggest that reducing food insecurity (for example, ,by improving access to nutritious food and combining nutritional supports with mental‑health care) may help lower ADHD risk or reduce symptoms in some children. Reducing food insecurity should be a priority for society, but it is premature to conclude it will reduce the risk for ADHD. We know that parents with ADHD are more likely to lose their jobs and have lower incomes compared to parents with ADHD. That might create food insecurity for their children who we know are at high risk for ADHD from genetic studies.
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