Drugs for attention deficit-hyperactivity disorder do not increase the mid-term risk of sudden death in children: a meta-analysis of observational studies

ADHD medications use and risk of mortality and unintentional injuries: a population-based cohort study

We assessed the association between the use of medications for attention-deficit/hyperactivity disorder (ADHD) and the risk of all-cause mortality and unintentional injuries leading to emergency department (ED) or hospital admission in individuals aged ≤24 years with ADHD. We conducted a population-based retrospective cohort study between 2000 and 2021 using Quebec health administrative data. Individuals were followed from the first ADHD diagnosis or ADHD medication claim until turning 25, death, or study end. Exposure was defined as mutually exclusive episodes of ADHD medication use and/or coverage under the public provincial drug plan (PDP): 1) covered and not treated with ADHD medication; 2) covered and treated with ADHD medication; and 3) not covered under the PDP. The risk of all-cause mortality and unintentional injuries associated with exposure episodes was estimated using multivariable survival analyses. The cohort included n = 217 192 individuals aged 1-24 years with a male to female ratio of close to 2:1. Compared to non-medication use, episodes of ADHD medication use, overall, were associated with reduced all-cause mortality (adjusted hazard ratio, aHR 0.61, 95% CI 0.48-0.76) and unintentional injury leading to ED (0.75, 0.74-0.77) or hospitalisation (0.71, 0.68-0.75). Episodes of stimulants were associated with a lower risk of all-cause mortality and reduced risk of unintentional injuries, while episodes with non-stimulants and with both stimulants and non-stimulants concomitantly were associated with reduced risk of unintentional injuries, but not of all-cause mortality. Although residual confounding cannot be excluded, stimulants may have a protective effect in terms of risk of all-cause mortality and both stimulants and non-stimulants for ADHD may reduce the risk of unintentional injuries. The findings of the current study should inform clinical decision making on the choice of starting a pharmacological treatment for ADHD, when a balance needs to be struck between expected benefits and possible risks.

Adverse Effects of Stimulant Interventions for Attention Deficit Hyperactivity Disorder (ADHD): A Comprehensive Systematic Review

Attention deficit hyperactivity disorder (ADHD) is a fairly common psychiatric disorder among children. It has substantial consequences in terms of quality of life for those experiencing it and their families. In managing ADHD symptoms medication plays an essential role, including stimulants such as methylphenidate being a key component. Nevertheless, concerns have been raised about possible adverse reactions connected to these drugs. Thus, in this systematic review, an extensive analysis was conducted aiming at understanding any negative repercussions specifically from prolonged exposure to these medications among patients diagnosed with ADHD. The methodology entailed adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. While capturing relevant data through a meticulous search in various databases, filtered according to preset inclusion and exclusion criteria, 13 studies were considered for analysis. Conclusions indicate that the administration of stimulant medications can potentially translate into a small rise in blood pressure along with increased heart rate particularly when amphetamines are taken. However, no reports of notable serious cardiovascular events have emerged. In the domain of neuropsychiatry, it appears that long-term usage of methylphenidate generally bears no serious consequences, even though a hike in risk levels related to the occurrence of psychotic episodes was detected among those treated with amphetamines. Several gastrointestinal side effects including decreased appetite and stomach pain were reported, however, findings regarding ocular abnormalities or growth-related effects stood inconclusive. Therefore, based on this data the consensus is that stimulant medications do generate manageable and mild negative outcomes within the ADHD population. It is vital however to highlight the need for careful observation and further scientific inquiry to achieve a better grasp on both immediate as well as long-term implications involved.

Risk of Cardiovascular Diseases Associated With Medications Used in Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-analysis

IMPORTANCE

Use of attention-deficit/hyperactivity disorder (ADHD) medications has increased substantially over the past decades, but there are concerns regarding their cardiovascular safety.

OBJECTIVE

To provide an updated synthesis of evidence on whether ADHD medications are associated with the risk of a broad range of cardiovascular diseases (CVDs).

DATA SOURCES

PubMed, Embase, PsycINFO, and Web of Science up to May 1, 2022.

STUDY SELECTION

Observational studies investigating the association between ADHD medications (including stimulants and nonstimulants) and risk of CVD.

DATA EXTRACTION AND SYNTHESIS

Independent reviewers extracted data and assessed study quality using the Good Research for Comparative Effectiveness (GRACE) checklist. Data were pooled using random-effects models. This study is reported according to the Meta-analyses of Observational Studies in Epidemiology guideline.

MAIN OUTCOMES AND MEASURES

The outcome was any type of cardiovascular event, including hypertension, ischemic heart disease, cerebrovascular disease, heart failure, venous thromboembolism, tachyarrhythmias, and cardiac arrest.

RESULTS

Nineteen studies (with 3 931 532 participants including children, adolescents, and adults; 60.9% male), of which 14 were cohort studies, from 6 countries or regions were included in the meta-analysis. Median follow-up time ranged from 0.25 to 9.5 years (median, 1.5 years). Pooled adjusted relative risk (RR) did not show a statistically significant association between ADHD medication use and any CVD among children and adolescents (RR, 1.18; 95% CI, 0.91-1.53), young or middle-aged adults (RR, 1.04; 95% CI, 0.43-2.48), or older adults (RR, 1.59; 95% CI, 0.62-4.05). No significant associations for stimulants (RR, 1.24; 95% CI, 0.84-1.83) or nonstimulants (RR, 1.22; 95% CI, 0.25-5.97) were observed. For specific cardiovascular outcomes, no statistically significant association was found in relation to cardiac arrest or arrhythmias (RR, 1.60; 95% CI, 0.94-2.72), cerebrovascular diseases (RR, 0.91; 95% CI, 0.72-1.15), or myocardial infarction (RR, 1.06; 95% CI, 0.68-1.65). There was no associations with any CVD in female patients (RR, 1.88; 95% CI, 0.43-8.24) and in those with preexisting CVD (RR, 1.31; 95% CI, 0.80-2.16). Heterogeneity between studies was high and significant except for the analysis on cerebrovascular diseases.

CONCLUSIONS AND RELEVANCE

This meta-analysis suggests no statistically significant association between ADHD medications and the risk of CVD across age groups, although a modest risk increase could not be ruled out, especially for the risk of cardiac arrest or tachyarrhythmias. Further investigation is warranted for the cardiovascular risk in female patients and patients with preexisting CVD as well as long-term risks associated with ADHD medication use.

The use of attention-deficit hyperactivity disorder medications in cardiac disease

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder with onset usually in childhood characterized by inattention, impulsivity, and hyperactivity causing a functional impairment. Untreated ADHD, or treatment delay is associated with adverse outcomes and poor quality of life. Although conservative management strategies such as behavioral and psychological interventions are important, pharmacological treatment has a strong evidence base with improved outcomes. ADHD medications are broadly divided into stimulant and non-stimulant medications. Stimulant medications are generally more effective than non-stimulants. Cardiovascular safety of ADHD medication has been a matter of debate for decades. Treatment guidelines advise the careful consideration of risks and benefits in people with cardiovascular diseases such as congenital heart disease or cardiomyopathy. Although stimulants can increase systemic blood pressure and heart rate, no significant associations were found between their use and serious cardiovascular events. Concerns regarding QT effects and attendant sudden cardiac death risks deter clinicians from initiating much-needed ADHD medications in patients with heart disease. This overly cautious approach is potentially depriving low-risk individuals from significant benefits associated with timely ADHD drug treatment. This review discusses the cardiovascular risks reportedly associated with ADHD medications, the evidence base for their safe usage in persons with established cardiovascular disease, and highlights future research directions.

Evidence-based pharmacological treatment options for ADHD in children and adolescents

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity, causing functional impairment. Its prevalence lies at approximately 5% in children and adolescents and at approximately 2.5% in adults. The disorder follows a multifactorial etiology and shows a high heritability. Patients show a high interindividual and intraindividual variability of symptoms, with executive deficits in several cognitive domains. Overall, ADHD is associated with high rates of psychiatric comorbidities, and insufficient treatment is linked to adverse long-term outcomes. Current clinical guidelines recommend an individualized multimodal treatment approach including psychoeducation, pharmacological interventions, and non-pharmacological interventions. Available medications include stimulants (methylphenidate, amphetamines) and non-stimulants (atomoxetine, guanfacine, clonidine). While available pharmacological treatment options for ADHD show relatively large effect sizes (in short-term trials) and overall good tolerability, there is still a need for improvement of current pharmacotherapeutic strategies and for the development of novel medications. This review summarizes available pharmacological treatment options for ADHD in children and adolescents, identifies current issues in research and evidence gaps, and provides an overview of ongoing efforts to develop new medications for the treatment of ADHD in children and adolescents by means of a systematic cross-sectional analysis of the clinical trials registry www.clinicaltrials.gov.

Methylphenidate and mortality in children with attention-deficit hyperactivity disorder: population-based cohort study

BACKGROUND

Little is known about methylphenidate (MPH) use and mortality outcomes.

AIMS

To investigate the association between MPH use and mortality among children with an attention-deficit hyperactivity disorder (ADHD) diagnosis.

METHOD

This population-based cohort study analysed data from Taiwan's National Health Insurance Research Database (NHIRD). A total of 68 096 children and adolescents aged 4-17 years with an ADHD diagnosis and prescribed MPH between 2000 and 2010 were compared with 68 096 without an MPH prescription, matched on age, gender and year of first ADHD diagnosis. All participants were followed to death, migration, withdrawal from the National Health Insurance programme or 31 December 2013. MPH prescriptions were measured on a yearly basis during the study period, and the association between MPH use and mortality was analysed using a repeated-measures time-dependent Cox regression model. The outcome measures included all-cause, unnatural-cause (including suicide, accident and homicide) and natural-cause mortality, obtained from linkage to the National Mortality Register in Taiwan.

RESULTS

The MPH group had lower unadjusted all-cause, natural-, unnatural- and accident-cause mortality than the comparison group. After controlling for potential confounders, MPH use was associated with a significantly lower all-cause mortality (adjusted hazard ratio AHR = 0.81, 95% CI 0.67-0.98, P = 0.027), delayed use of MPH was associated with higher mortality (AHR = 1.05, 95% CI 1.01-1.09) and longer MPH use was associated with lower mortality (AHR = 0.83, 95% CI 0.70-0.98).

CONCLUSIONS

MPH use is associated with a reduced overall mortality in children with ADHD in this cohort study, but unmeasured confounding cannot be excluded absolutely.

Association of ADHD medications with the risk of cardiovascular diseases: a meta-analysis

This meta-analysis was conducted to evaluate the association between Attention deficit hyperactivity disorder (ADHD) medications and risk of sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death. We searched PubMed, Web of Science and China National Knowledge Infrastructure from 1950 to May 2018. All observational studies that the exposure of interest was ADHD medications, the outcome of interest was sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death, and the study reported relative risks (RRs) with 95% confidence intervals (95% CIs) were included. Pooled RRs were estimated by random-effects model. Subgroup analyses were conducted to examine the effects of study design, population, Country, follow-up duration, female proportion, covariates adjustment on the risk of sudden death/arrhythmia. Eight articles with ten studies (4,221,929 participants) were included in this meta-analysis about the association between ADHD medications and risk of sudden death/arrhythmia. The pooled RRs with 95% CIs of sudden death/arrhythmia for ADHD medications were 1.39 (1.06, 1.83). The result of the cohort study was 1.24 (0.84, 1.83). The pooled RRs between ADHD medications and stroke, myocardial infarction, all-cause death were 1.00 (0.74, 1.35), 0.91 (0.79, 1.05), 0.89 (0.54, 1.45), respectively. As for methylphenidate, the pooled RRs between methylphenidate and sudden death/arrhythmia, stroke, myocardial infarction, all-cause death were 1.46 (1.03, 2.07), 0.92 (0.70, 1.21), 0.97 (0.77, 1.23), 1.00 (0.49, 2.04), respectively. Based on the results of cohort studies, there was no correlation between ADHD medications and sudden death/arrhythmia, stroke, myocardial infarction and all-cause death. However, some of the confidence intervals do not exclude modest elevated risks, e.g., for sudden death/arrhythmia.

Cardiovascular Safety of Concomitant Use of Atypical Antipsychotics and Long-Acting Stimulants in Children and Adolescents With ADHD

OBJECTIVE

This study examined cardiovascular safety of concomitant use of long-acting stimulants (LAS) and atypical antipsychotics (AAP) in children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD).

METHOD

The study used 2004-2007 IMS LifeLink™ claims data involving 6- to 16-year-old children with ADHD and at least one LAS prescription from July 2004 to December 2006. Time-dependent Cox regression analysis was performed to evaluate the risk of cardiovascular disease (CVD) events due to concomitant use of LAS and AAP.

RESULTS

The analytical cohort consisted of 37,903 children: 538 (1.9%) used LAS and AAP concurrently and the rest used LAS monotherapy. Time-dependent Cox regression analysis revealed no difference in CVD risk among concomitant users of LAS and AAP (hazard ratio = 1.19; 95% confidence interval = [0.60, 2.53]) when compared with users of LAS monotherapy.

CONCLUSION

Concomitant use of LAS and AAP was not associated with risk of CVD events in ADHD patients when compared with LAS monotherapy.

Twenty years of progress in paediatric psychopharmacology: accomplishments and unmet needs

The systematic assessment of the efficacy and safety of psychiatric medications in children and adolescents started about 20 years ago. Since then, a considerable number of randomised clinical trials have been conducted, including also a series of publicly funded comparative effectiveness studies to evaluate the therapeutic benefit of medications relative to psychosocial interventions, alone or combined with medications. On the whole, these studies have been informative of the paediatric pharmacokinetics, efficacy and safety of the most commonly used psychotropics. As a consequence, a number of meta-analyses have been conducted that have documented both the benefits and harms of the most common medication groups, such as stimulants, antidepressants and antipsychotics. Evidence-based practice guidelines have been produced, and clinicians can now better estimate the therapeutic value and the risk of treatment, at least at the group mean level. However, most clinical trials have been conducted in research settings, and this limits the generalisability of the results. There is a need for evaluating treatment effects under usual practice conditions, through practical trials. The ongoing debate about the proper role of pharmacotherapy in child mental health can be advanced by comparative effectiveness research to assess the benefit/risk ratio of pharmacotherapy vis-à-vis alternative treatment modalities. In addition, analyses of large population databases can better inform on the impact of early treatment on important distal outcomes, such as interpersonal functioning, social and occupational status, quality of life and risk for disability or mortality. Thus far, paediatric psychopharmacology has been mostly the application to children of medications that were serendipitously discovered and developed for adults. By focusing on the neurobiological mechanisms of child psychopathology, it may be possible to identify more precise pharmacological targets and arrive at a truly developmental psychopharmacology.

Effects of long-term methylphenidate use on growth and blood pressure: results of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)

BACKGROUND

Concerns have been raised over the safety of methylphenidate (MPH), with regard to adverse effects on growth and blood pressure. Our study investigates whether, and to what extent, methylphenidate use in boys with ADHD is associated with having low body mass index (BMI), having low height, and increased systolic and diastolic blood pressure.

METHODS

Data used for this study stem from the German KiGGS dataset. Three different groups of boys aged 6-15 years were included in the analysis: ADHD patients who used MPH for less than 12 months; ADHD patients who used MPH for 12 months or more; and ADHD patients without current MPH treatment. Each of these three groups was compared to a non-ADHD control group regarding low weight (BMI ≤ 3rd percentile), low height (≤3rd percentile) and raised systolic and diastolic blood pressure. For growth outcomes, boys were categorized according to age (< 11 years/≥11 years, to account for pubertal maturation). Multivariable logistic regression was conducted to test for associations.

RESULTS

4244 boys were included in the study; MPH < 12 months: n = 65 (n = 36 < 11 years), MPH ≥ 12 months: n = 53 (n = 22 < 11 years), ADHD controls: n = 320 (n = 132 < 11 years), non-ADHD controls: n = 3806 (n = 2003 < 11 years). Pre-pubertal boys with MPH use less than 12 months and pubertal/postpubertal boys with MPH use of 12 months or greater were significantly more likely to have a BMI ≤ 3rd percentile compared to non-ADHD controls. Boys from the ADHD control group were significantly less likely to have a raised systolic blood pressure compared to non-ADHD controls. Beyond that, no significant between group differences were observed for any other growth and BP parameter.

CONCLUSION

The analyses of the KiGGS dataset showed that MPH use in boys with ADHD is associated with low BMI. However, this effect was only observed in certain groups. Furthermore, our analysis was unable to confirm that MPH use is also associated with low height (≤3rd percentile) and changes in blood pressure.

An update on the safety of psychostimulants for the treatment of attention-deficit/hyperactivity disorder

INTRODUCTION

Methylphenidate is the first-line pharmacological treatment of attention-deficit/hyperactivity disorder (ADHD). Although methylphenidate has a well-established evidence base for treating ADHD, its long-term benefits are unclear. Areas covered: Physical adverse effects, psychiatric adverse events and brain development Expert opinion: Some physical adverse events have been described (e.g. sleep disturbances, growth reduction, loss of appetite), although most are of transient nature. Psychiatric adverse events seem more related to the diagnosis ADHD itself, and not stimulant treatment. Concluding, short-to-mid-term use (i.e., up to 2 years) stimulants are relatively safe, but much less is known about longer-term efficacy and safety of these drugs.

Cardiovascular Effects of Stimulant and Non-Stimulant Medication for Children and Adolescents with ADHD: A Systematic Review and Meta-Analysis of Trials of Methylphenidate, Amphetamines and Atomoxetine

BACKGROUND

Many children and adolescents with attention deficit/hyperactivity disorder (ADHD) are treated with stimulant and non-stimulant medication. ADHD medication may be associated with cardiovascular effects. It is important to identify whether mean group effects translate into clinically relevant increases for some individual patients, and/or increase the risk for serious cardiovascular adverse events such as stroke or sudden death.

OBJECTIVES

To evaluate potential cardiovascular effects of these treatments, we conducted a systematic review and meta-analysis of the effects of methylphenidate (MPH), amphetamines (AMP), and atomoxetine (ATX) on diastolic and systolic blood pressure (DBP, SBP) and heart rate (HR) in children and adolescents with ADHD.

METHODS

We conducted systematic searches in electronic databases (PsychINFO, EMBASE and Medline) to identify published trials which involved individuals who were (i) diagnosed with ADHD and were aged between 0-18 years; (ii) treated with MPH, AMP or ATX and (iii) had their DBP and SBP and/or HR measured at baseline (pre) and the endpoint (post) of the study treatment. Studies with an open-label design or a double-blind randomised control design of any duration were included. Statistical analysis involved calculating differences between pre- and post-treatment measurements for the various cardiovascular parameters divided by the pooled standard deviation. Further, we assessed the percentage of clinically relevant increased BP or HR, or documented arrhythmias.

RESULTS

Eighteen clinical trials met the inclusion criteria (10 for MPH, 5 for AMP, and 7 for ATX) with data from 5837 participants (80.7% boys) and average duration of 28.7 weeks (range 4-96 weeks). All three medications were associated with a small, but statistically significant pre-post increase of SBP (MPH: standard mean difference [SMD] 0.25, 95% confidence interval [CI] 0.08-0.42, p < 0.01; AMP: SMD 0.09, 95% CI 0.03-0.15, p < 0.01; ATX: SMD 0.16, 95% CI 0.04-0.27, p = 0.01). MPH did not have a pre-post effect on DBP and HR. AMP treatment was associated with a small but statistically significant pre-post increase of DBP (SMD 0.16, CI 0.03-0.29, p = 0.02), as was ATX treatment (SMD 0.22, CI 0.10-0.34, p < 0.01). AMP and ATX were associated with a small to medium statistically significant pre-post increase of HR (AMP: SMD 0.37, CI 0.13-0.60, p < 0.01; ATX: SMD 0.43, CI 0.26-0.60, p < 0.01). The head-to-head comparison of the three medications did not reveal significant differences. Sensitivity analyses revealed that AMP studies of <18 weeks reported higher effect sizes on DBP compared with longer duration studies (F(1) = 19.55, p = 0.05). Further, MPH studies published before 2007 reported higher effect sizes on SBP than studies after 2007 (F(1) = 5.346, p = 0.05). There was no effect of the following moderators: type of medication, doses, sample size, age, gender, type of ADHD, comorbidity or dropout rate. Participants on medication reported 737 (12.6%) other cardiovascular effects. Notably, 2% of patients discontinued their medication treatment due to any cardiovascular effect. However, in the majority of patients, the cardiovascular effects resolved spontaneously, medication doses were changed or the effects were not considered clinically relevant. There were no statistically significant differences between the medication treatments in terms of the severity of cardiovascular effects.

CONCLUSIONS

Statistically significant pre-post increases of SBP, DBP and HR were associated with AMP and ATX treatment in children and adolescents with ADHD, while MPH treatment had a statistically significant effect only on SBP in these patients. These increases may be clinically significant for a significant minority of individuals that experience larger increases. Since increased BP and HR in general are considered risk factors for cardiovascular morbidity and mortality during adult life, paediatric patients using ADHD medication should be monitored closely and regularly for HR and BP.

Attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a persistent neurodevelopmental disorder that affects 5% of children and adolescents and 2.5% of adults worldwide. Throughout an individual's lifetime, ADHD can increase the risk of other psychiatric disorders, educational and occupational failure, accidents, criminality, social disability and addictions. No single risk factor is necessary or sufficient to cause ADHD. In most cases ADHD arises from several genetic and environmental risk factors that each have a small individual effect and act together to increase susceptibility. The multifactorial causation of ADHD is consistent with the heterogeneity of the disorder, which is shown by its extensive psychiatric co-morbidity, its multiple domains of neurocognitive impairment and the wide range of structural and functional brain anomalies associated with it. The diagnosis of ADHD is reliable and valid when evaluated with standard criteria for psychiatric disorders. Rating scales and clinical interviews facilitate diagnosis and aid screening. The expression of symptoms varies as a function of patient developmental stage and social and academic contexts. Although there are no curative treatments for ADHD, evidenced-based treatments can markedly reduce its symptoms and associated impairments. For example, medications are efficacious and normally well tolerated, and various non-pharmacological approaches are also valuable. Ongoing clinical and neurobiological research holds the promise of advancing diagnostic and therapeutic approaches to ADHD. For an illustrated summary of this Primer, visit: http://go.nature.com/J6jiwl.

Mortality in children, adolescents, and adults with attention deficit hyperactivity disorder: a nationwide cohort study

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common mental disorder associated with factors that are likely to increase mortality, such as oppositional defiant disorder or conduct disorder, criminality, accidents, and substance misuse. However, whether ADHD itself is associated with increased mortality remains unknown. We aimed to assess ADHD-related mortality in a large cohort of Danish individuals.

METHODS

By use of the Danish national registers, we followed up 1·92 million individuals, including 32,061 with ADHD, from their first birthday through to 2013. We estimated mortality rate ratios (MRRs), adjusted for calendar year, age, sex, family history of psychiatric disorders, maternal and paternal age, and parental educational and employment status, by Poisson regression, to compare individuals with and without ADHD.

FINDINGS

During follow-up (24·9 million person-years), 5580 cohort members died. The mortality rate per 10,000 person-years was 5·85 among individuals with ADHD compared with 2·21 in those without (corresponding to a fully adjusted MRR of 2·07, 95% CI 1·70-2·50; p<0·0001). Accidents were the most common cause of death. Compared with individuals without ADHD, the fully adjusted MRR for individuals diagnosed with ADHD at ages younger than 6 years was 1·86 (95% CI 0·93-3·27), and it was 1·58 (1·21-2·03) for those aged 6-17 years, and 4·25 (3·05-5·78) for those aged 18 years or older. After exclusion of individuals with oppositional defiant disorder, conduct disorder, and substance use disorder, ADHD remained associated with increased mortality (fully adjusted MRR 1·50, 1·11-1·98), and was higher in girls and women (2·85, 1·56-4·71) than in boys and men (1·27, 0·89-1·76).

INTERPRETATION

ADHD was associated with significantly increased mortality rates. People diagnosed with ADHD in adulthood had a higher MRR than did those diagnosed in childhood and adolescence. Comorbid oppositional defiant disorder, conduct disorder, and substance use disorder increased the MRR even further. However, when adjusted for these comorbidities, ADHD remained associated with excess mortality, with higher MRRs in girls and women with ADHD than in boys and men with ADHD. The excess mortality in ADHD was mainly driven by deaths from unnatural causes, especially accidents.

FUNDING

This study was supported by a grant from the Lundbeck Foundation.