People with ADHD face a risk of premature death 1.5 to 8 times greater than those without the disorder. That’s the conclusion of a new study involving 32,000 Danes with ADHD and more than a million Danes without the disorder.
The new study underlines the necessity of taking the ADHD disorder very seriously, says the scientist behind the study, senior researcher Søren Dalsgaard from the the National Centre for Register-based Research, Aarhus University.
"We can use this study as documentation to the fact that ADHD is a valid disorder. It’s a psychiatric disorder which has a huge effect on patients' everyday lives and the effect also manifests itself in the worst thinkable way -- namely the increased risk of premature death," says Dalsgaard.
According to the study, recently published in The Lancet, the risk of dying prematurely is twice as high if you have an ADHD diagnosis compared to mortality rate of the background population.
Although the relative risk of dying prematurely is higher than that in people without ADHD, the actual numbers of deaths in the overall study population is very low.
Of the 32,000 Danes with ADHD, 107 of them died prematurely measured over a period of some 32 years.
"That might seem like a very small number, and it is. But it’s more than twice as many as in the control group," says Dalsgaard. “The most frequent cause of death was accidents.”
Previous studies have hinted at the same.
"We know that having ADHD increases your risk of having an accident and that people with ADHD are more frequently involved in traffic accidents -- which makes sense because having difficulty concentrating is a risk factor in traffic," he says.
The findings have been corrected for factors such as gender, parental income and mental illness among parents, explains Dailsgaard.
The study also show that the age at which people are diagnosed with ADHD also plays a role when it comes to premature death.
"If you’re diagnosed as an adult you face a greater risk than if you’d been diagnosed in childhood," says Dalsgaard.
He explains that the risk of dying prematurely was 2.2 times greater for children who were between 6 and 17 years old at the time of diagnosis, while the risk was 4.6 per cent for those diagnosed after reaching 18.
Comparing girls with boys, girls with ADHD are at three times the risk of dying early compared to the control group, whereas boys with ADHD have close to twice the risk of premature death compared to the control.
"The figures suggest that we should take ADHD seriously and that people in vulnerable situations need help," says Dalsgaard.
The increased mortality rate among people with ADHD comes as no surprise to Per Hove Thomsen, a professor of child and youth psychiatry at Aarhus University Hospital, Risskov.
"It's something we've known about on a smaller scale from other studies, including clinical studies," says Thomsen. "However, this study distinguishes itself by having been done on such a huge data material."
He explains that the increased mortality could be due to the fact that ADHD involves a high degree of impulsiveness -- meaning that you don't think carefully enough when in or near busy traffic.
If a person with ADHD also has behavioural problems, there is a greater risk of them getting into criminal environments and becoming involved in violent episodes. People with ADHD are also more prone to drug abuse, which in itself damages their health and makes them more vulnerable, says Thomsen.
One of the weaknesses of the new study is that its findings cannot necessarily be transferred from Denmark to other countries.
"We treat fewer people with ADHD in Denmark than they do for instance in the United States. This may therefore mean that that only people with the most severe ADHD get diagnosed here [in Denmark]. So it's by no means certain that people with milder ADHD also face a greater risk of premature death," says Dalsgaard.
Furthermore, the scientists are also unable to say anything about the effect of treatment.
"You don't know whether treatment has an effect on mortality. The burning question is if there’s anything we can do to reduce mortality. That will be the next step," says Dalsgaard.