ADHD has long been associated with higher rates of criminal behavior, but most studies have relied heavily on self-reported data and small, non-representative samples. A new Swedish study addresses these limitations, providing a more comprehensive and reliable picture using data from nationwide registers. It sheds light on the role of ADHD medication in reducing the risk of criminal convictions, offering insights for clinicians, policymakers, and families.
Earlier research, such as a 2019 Danish study, found that ADHD diagnosed in children and adolescents ages 4 to 15 was associated with a 1.6-fold increased risk of future criminal conviction. However, these findings were limited by a smaller sample size and a focus on just one nation’s context. Like Denmark, Sweden’s single-payer universal healthcare system allows for the collection of extensive data on health and crime records, providing an ideal environment for large-scale, population-based research.
To investigate ADHD’s connection to criminal behavior, the Swedish research team analyzed records from a cohort of 1,646,645 individuals born between 1986 and 1997. They excluded those who died or emigrated before age 15 (the age of criminal responsibility in Sweden) and those who immigrated to Sweden, resulting in a final study group of 1,235,939 individuals. Slightly more than half of the cohort was male.
ADHD diagnoses were based on clinical records and prescriptions for approved ADHD medications, while criminal convictions—both violent and nonviolent—were identified using Sweden’s National Crime Register, covering the years 2001 to 2013. The study adjusted for various potential confounding factors, including sex, birth year, parental education, and other psychiatric conditions. They also used the Swedish Multi-Generation Register to control for unmeasured familial factors to compare outcomes among full siblings.
The study found that ADHD is strongly associated with increased rates of criminal convictions. Compared to individuals without ADHD, those with an ADHD diagnosis were roughly:
Interestingly, when comparing conviction rates among males and females with ADHD, the rates of nonviolent convictions were similar, but females with ADHD were about 25% more likely to be convicted of a violent crime than males with ADHD.
The research also highlighted the importance of ADHD medication in reducing criminal behavior. When individuals with ADHD who were taking medication were excluded from the analysis, the data showed significantly higher rates of criminal convictions:
These findings suggest that ADHD medications can significantly reduce the risk of both violent and nonviolent criminal behavior in individuals with ADHD, emphasizing the value of pharmacological treatment for those with the condition.
The researchers concluded that “ADHD is a strong risk factor for both violent and non‐violent criminal convictions in males and females even after adjustments for psychiatric comorbidities and unmeasured familial factors.” The study also found that untreated ADHD poses a particularly high risk for criminal behavior, highlighting the protective role of medication.
These findings are clinically relevant for several reasons. First, they reinforce the importance of ensuring that individuals with ADHD have access to effective treatment options, especially during the transition from adolescence into adulthood, which is statistically a period of higher risk for criminal behavior. Additionally, the study provides critical data for shaping public policy and interventions aimed at supporting individuals with ADHD, with a focus on reducing criminality through proper management of the disorder.
This study offers new insights into the complex relationship between ADHD, medication, and criminal behavior, emphasizing the crucial role of treatment in mitigating risks. It provides a compelling case for prioritizing access to ADHD medication as part of a broader strategy for supporting those with ADHD.
Anna-Karin Ångström, Anneli Andersson, Miguel Garcia-Argibay, Zheng Chang, Paul Lichtenstein, Brian M. D’Onofrio, Catherine Tuvblad, Laura Ghirardi, and Henrik Larsson, “Criminal convictions in males and females diagnosed with attention deficit hyperactivity disorder: A Swedish national registry study,” JCPP Advances (2024), e12217, https://doi.org/10.1002/jcv2.12217.
A Chinese research team performed two types of meta-analyses to compare the risk of suicide for ADHD patients taking ADHD medication as opposed to those not taking medication.
The first type of meta-analysis combined six large population studies with a total of over 4.7 million participants. These were located on three continents - Europe, Asia, and North America - and more specifically Sweden, England, Taiwan, and the United States.
The risk of suicide among those taking medication was found to be about a quarter less than for unmediated individuals, though the results were barely significant at the 95 percent confidence level (p = 0.49, just a sliver below the p = 0.5 cutoff point). There were no significant differences between males and females, except that looking only at males or females reduced sample size and made results non-significant.
Differentiating between patients receiving stimulant and non-stimulant medications produced divergent outcomes. A meta-analysis of four population studies covering almost 900,000 individuals found stimulant medications to be associated with a 28 percent reduced risk of suicide. On the other hand, a meta-analysis of three studies with over 62,000 individuals found no significant difference in suicide risk for non-stimulant medications. The benefit, therefore, seems limited to stimulant medication.
The second type of meta-analysis combined three within-individual studies with over 3.9 million persons in the United States, China, and Sweden. The risk of suicide among those taking medication was found to be almost a third less than for unmediated individuals, though the results were again barely significant at the 95 percent confidence level (p =0.49, just a sliver below the p = 0.5 cutoff point). Once again, there were no significant differences between males and females, except that looking only at males or females reduced the sample size and made results non-significant.
Differentiating between patients receiving stimulant and non-stimulant medications once again produced divergent outcomes. Meta-analysis of the same three studies found a 25 percent reduced risk of suicide among those taking stimulant medications. But as in the population studies, a meta-analysis of two studies with over 3.9 million persons found no reduction in risk among those taking non-stimulant medications.
A further meta-analysis of two studies with 3.9 million persons found no reduction in suicide risk among persons taking ADHD medications for 90 days or less, "revealing the importance of duration and adherence to medication in all individuals prescribed stimulants for ADHD."
The authors concluded, "exposure to non-stimulants is not associated with a higher risk of suicide attempts. However, a lower risk of suicide attempts was observed for stimulant drugs. However, the results must be interpreted with caution due to the evidence of heterogeneity ..."
A team of German researchers explored five million member records from a database that tracks more than sixty nationwide statutory health insurance programs. The database closely tracks the characteristics of the overall German population.
This was a longitudinal cohort study, tracking individuals first diagnosed with adult ADHD between 2013 and 2017. Anyone who was not continuously insured during this period was excluded, as were those who died, plus anyone older than 55 to prevent bias from high morbidity in the top age brackets.
The study team used the database to add up direct healthcare costs, including inpatient care, outpatient care, psychotherapy, medical aids and remedies, medication, and sickness benefits. In Germany, sickness benefits kick in after more than six weeks of continuous inability to work.
The study tracked data within a window extending both four years back and four years forward from the initial adult ADHD diagnosis.
The resulting study cohort consisted of 2,380 persons between 18 and 55, initially diagnosed with ADHD at an average age of 35. Sixty percent were male.
One-third were prescribed ADHD medication upon diagnosis. Four years later, only one-eighth were still on medication.
Almost two-thirds received psychotherapy, dropping to under a third in succeeding years.
During the year following diagnosis, average healthcare costs totaled about €4,000 per individual. For those who initiated ADHD medication, the average cost was just over €5,400, and for those who did not it was almost €3,500.
The authors concluded, "An important finding of the present investigation is that in the year of initial diagnosis, less than one-third of individuals received any prescription of ADHD-specific medication, and only a fourth got at least two prescriptions. At the same time, almost two-thirds of individuals received psychotherapy in the year of ADHD[adult ADHD] diagnosis. In about one-third of individuals, psychotherapy had been initiated already before a diagnosis of ADHD, presumably for treatment of comorbid disorders. ... In current German guidelines, ADHD-specific medication is recommended as the first choice ... Apparently, despite the vast body of evidence for the beneficial effects of ADHD-specific medication, at least in the short-term, and in contrast to the recommendations of previous and current guidelines, stimulant medication is only reluctantly prescribed in newly identified adults with ADHD. ... Overall, our findings suggest that significant deficiencies may currently exist concerning the reality of healthcare for ADHD in Germany, and that guideline recommendations are not yet comprehensively implemented in everyday routine care."
Older adults are at greater risk for cardiovascular disease. Psychostimulants may contribute to that risk through side effects, such as elevation of systolic blood pressure, diastolic blood pressure, and heart rate.
On the other hand, smoking, substance abuse, obesity, and chronic sleep loss - all of which are associated with ADHD - are known to increase cardiovascular risk, and stimulant medications are an effective treatment for ADHD.
So how does this all shake out? A Dutch team of researchers sets out to explore this. Using electronic health records, they compared all 139 patients 55 years and older at PsyQ outpatient clinic, Program Adult ADHD, in The Hague. Because a principal aim of the study was to evaluate the effect of medication on cardiovascular functioning after first medication use, the 26 patients who had previously been prescribed ADHD medication were excluded from the study, leaving a sample size of 113.
The ages of participants ranged from 55 from 79, with a mean of 61. Slightly over half were women. At the outset, 13 percent had elevated systolic and/or diastolic blood pressure, 2 percent had an irregular heart rate, 15 percent had an abnormal electrocardiogram, and 29 percent had some combination of these (a "cardiovascular risk profile"), and 21 percent used antihypertensive medication.
Three out of four participants had at least e comorbid disorder. The most common are sleep disorders, affecting a quarter of participants, and unipolar mood disorders (depressive or more rarely manic episodes, but not both), also affecting a quarter of participants.
Twenty-four patients did not initiate pharmacological treatment. Of the 89 who received ADHD medication, 58 (65%) reported positive effects, and five experienced no effect. Thirty-eight (43%) discontinued ADHD medication while at the clinic due to lack of effect or to side effects. The most commonly reported positive effects were enhanced concentration, more overview, less restlessness, more stable mood, and having more energy. The principal reasons for discontinuing medication were anxiety/depression, cardiovascular complaints, and lack of effect.
Methylphenidate raised heart rate and lowered weight, but had no significant effect on systolic and diastolic blood pressure. Moreover, there was no significant correlation between methylphenidate dosage and any of these variables, nor between methylphenidate users taking hypertensive medication and those not taking such medication. There was no significant difference in systolic or diastolic blood pressure and heart rate before and after the use of methylphenidate among patients with the cardiovascular risk profiles.
Systolic blood pressure rose in ten out of 64 patients, with two experiencing an increase of at least 20 mmHg. It descended in five patients, with three having a decrease of at least 20 mmHg. Diastolic blood pressure rose by at least 10 mmHg in four patients, while dropping at least 10 mmHg in five others.
The authors concluded "that the use of a low dose of ADHD-medication is well tolerated and does not cause clinically significant cardiovascular changes among older adults with ADHD, even among those with an increased cardiovascular risk profile. Furthermore, our older patients experienced significant and clinically relevant improvement of their ADHD symptoms using stimulants, comparable with what is found among the younger age group," and that "the use of methylphenidate may be a relatively safe and effective treatment for older adults with ADHD, under the condition that all somatic complaints and especially cardiovascular parameters are monitored before and during pharmacological treatment."
Yet they cautioned that "due to the observational nature of the study and the lack of a control group, no firm conclusions can be drawn as to the effectiveness of the stimulants used. ... Important factors that were not systematically reported were the presence of other risk factors, such as smoking, substance (ab)use, aspirin use, and level of physical activity. In addition, the response to medication was not systematically measured"
Maternal infections and inflammatory responses during pregnancy have been proposed as risk factors for neurodevelopmental disorders such as ADHD.
Taiwan has a single-payer health insurance system that covers virtually the entirety of its population. Its Ministry of Health and Welfare maintains the National Health Insurance Research Database (NHIRD), with detailed information on outpatient services, hospitalizations, and medical treatment for nearly 99% of all residents.
A Taiwanese study team used NHIRD to examine to examine the relationship between maternal hospitalization for infection, and early childhood infection, and subsequent ADHD in offspring. The study cohort originated with all 3,260,879 individuals born between 2001 and 2018.
The team excluded births from foreign mothers, still births, births with congenital defects, low birth weights, abnormally late births, twins, triplets, and other multiple births, culminating in a final population cohort of 2,885,662 live-born single infants across 1,893,171 families, and 1,864,660 individuals with full siblings from 872,169 families comprising the full sibling cohort.
Study participants were followed until diagnosis of a neurodevelopmental disorder, their death, or the end of 2021.
After adjusting for sex, birth year, paternal and maternal ages, birthweight, birth season, parity, delivery method, 1 minute APGAR score (evaluating baby’s appearance, pulse, grimace, activity and respiration at birth), gestational age, pregnancy and delivery complications, parental history of neurodevelopmental disorders, maternal asthma and diabetes, urbanization level of the residential area, and family’s insurance amount, offspring of mothers hospitalized for infections had 14% greater odds of being subsequently diagnosed with ADHD.
However, in the full sibling cohort of over 1.8 million, this association vanished. That held true for each of the three trimesters of pregnancy. It also held true for bacterial infections. Surprisingly, offspring of mothers hospitalized for viral infections were 24% less likely to be diagnosed with ADHD than their siblings not exposed to maternal viral infection. Because of that, they also had a 6% lower risk overall.
After the same adjustments, early childhood infection was associated with 16% greater odds of being diagnosed with ADHD.
Nevertheless, in the full sibling cohort of over 1.8 million, this association again vanished. That held true overall, as well as separately for childhood infections in months 1-6 and months 7-12. The association vanished altogether both for bacterial infections as well as for viral infections.
The authors concluded, “the results of this nationwide birth cohort study with population and sibling analyses suggest that the association between maternal infection during pregnancy and offspring neurodevelopmental risk is largely due to familial confounding factors.”
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.
Noting that “Recent research has demonstrated that some gut bacteria can affect the nervous system,” and speculating that “dysregulation in the gut microbiota may increase the incidence of ADHD by overproducing reactive oxygen and nitrogen species, thereby causing neuroinflammation and oxidative stress”, a Taiwanese study team decided to explore whether early-life use of antibiotics – in the first two years – is associated with increased risk of subsequent diagnosis of ADHD.
Because Taiwan has a single-payer national health insurance system that covers 99.8% of the island’s population, they were able to use the system’s National Health Insurance Research Database (NHIRD) and Maternal and Child Health Database (TMCHD) to include all 1.6 million children born between 2004 and 2012.
Of these, a little over 1.1 million were given antibiotics before turning two years old, and just over 460,000 were not given antibiotics in the same time frame.
The mean follow-up period for records of subsequent ADHD diagnoses was seven years.
The team adjusted for confounding variables: sex, gestational age at birth (weeks), and birth weight (grams) of the children, and age at birth (years), insurance amount (New Taiwan Dollar (TWD)), insurance location, method of delivery, comorbidities, and medication used during pregnancy.
With these adjustments, early-life antibiotics use was associated with a 12% increase in likelihood of being subsequently diagnosed with ADHD.
However, looking at the effects of antibiotics as an undifferentiated grouping turned out to be misleading, because the association was limited to only some classes of antibiotics.
Penicillins were associated with a 22% increase in risk of subsequent ADHD diagnosis, cephalosporins with a 10% increase.
On the other hand, there was absolutely no such association for tetracyclines, macrolides, and quinolones.
The Take-Away:
This study found that children in Taiwan who took certain types of antibiotics before age 2 had a slightly higher risk of developing ADHD later in life. More work is needed to determine if this finding is due to unmeasured confounding before a causal link can be concluded.
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