People with attention deficit hyperactivity disorder (ADHD) have a lower life expectancy and are more than twice as likely to die prematurely as those without the disorder, according to new research published in The Lancet. Accidents are the most common cause of death in people with ADHD, and the relative risk of dying is much higher for women than men with ADHD and individuals diagnosed in adulthood. The study is the first to shed light on the role of ADHD in premature death.

Led by Søren Dalsgaard from Aarhus University in Denmark, the large nationwide cohort study followed nearly 2 million individuals from the Danish national registers, including more than 32000 people with ADHD, from their first birthday to 2013 (a maximum of 32 years). The causes of premature death were assessed to compare individuals with and without ADHD.

During follow-up, 107 individuals with ADHD died. People diagnosed with ADHD were about twice as likely to die prematurely as people without the disorder, even after adjusting for factors known to affect the risk of early death including age, sex, family history of psychiatric disorders, maternal and paternal age, and parental education.

This increased risk of premature death in people with ADHD was mainly driven by deaths from unnatural causes, more than half of which were caused by accidents (42 deaths among 79 people for whom the cause of death was known). The risk of dying prematurely increased with age at diagnosis. For example, individuals diagnosed at age 18 years or older were more than four times as likely to die early compared with those without ADHD at the same age; whereas children diagnosed before the age of 6 years were at around double the risk of death compared with their healthy counterparts. The findings also reveal that girls and women with ADHD have a higher relative risk of premature death compared with boys and men with ADHD.

Previous research has shown that individuals with ADHD are more likely to have a range of co-existing disorders including oppositional defiant disorder, conduct disorder, and substance use disorders. People with ADHD who also had all three of these disorders were more than eight times as likely to die early than individuals without ADHD or any of these co-existing disorders.

According to Dr Dalsgaard, "Our findings emphasise the importance diagnosing ADHD early, especially in girls and women, and treating any co-existing antisocial and substance use disorders. It is however important to emphasise that although the relative risk of premature death is increased in ADHD, the absolute risk is low."

Writing in a linked Comment, Stephen Faraone, Professor of Psychiatry and Director of Child and Adolescent Psychiatry Research at SUNY Upstate Medical University in New York, USA, says, "For too long, the validity of ADHD as a medical disorder has been challenged. Policy makers should take heed of these data and allocate a fair share of health care and research resources to people with ADHD. For clinicians, early identification and treatment should become the rule rather than the exception."

Dr Faraone cautions, "Although talk of premature death will worry parents and patients, they can seek solace in the knowledge that the absolute risk for premature death is low and that this and other risks can be greatly reduced with evidenced-based treatments for the disorder."