Attention deficit hyperactivity disorder (ADHD) appears during childhood and often persists into adulthood, with a great impact on the lives of those affected. Previous epidemiological studies have shown that this disorder is associated with a lower life expectancy and a mortality up to five times higher than that of people without ADHD. A study led by the Vall d'Hebron Research Institute (VHIR), the Pere Virgili Health Research Institute (IISPV), the University Hospital Pere Mata Institute, the Mental Health CIBER (CIBERSAM) and Rovira i Virgili University (URV) has identified for the first time 19 genetic regions associated at the same time to this disorder and to a lower life expectancy.

This research work has been published in Neuropsychopharmacology. The above-mentioned institutions have collaborated with the University of California.

Up to 5 times higher mortality rate

Previous epidemiological studies have shown that this disorder is associated with a shorter life expectancy and a mortality rate up to five times higher than that of people without ADHD.
Now, researchers have combined results from two genome-wide association studies (GWAS) to find genetic variants, i.e., changes in the genome, associated with ADHD and life expectancy. Genetic data from 19,099 ADHD patients and 34,194 healthy people were analyzed. To analyze life expectancy they used data from about one million people.

The research identified 19 genetic regions associated with ADHD and life expectancy. "For the first time, this study identifies genes associated both with ADHD and lower life expectancy, which may help to explain previous epidemiological observations of increased mortality in patients with this disorder", says Dr. Maria Soler Artigas, a researcher in the Psychiatry, Mental Health and Addictions group at VHIR and CIBERSAM

Among the genes identified, TNKS plays an essential role in the maintenance of telomeres, the regions of the chromosomes involved in longevity, and is implicated in other psychiatric traits and metabolic disorders that often appear in patients with ADHD. The authors have also identified the AKAP6 and SEMA6D genes, previously related to other psychiatric disorders such as schizophrenia, or the SYPL2 and HMG20A genes, which have a relevant role in the control of different brain functions. "An interesting finding is that all genetic variants that increase the risk of ADHD reduce, at the same time, the length of life", explains Gerard Muntané, researcher at the IISPV, the University Hospital Pere Mata Institute and CIBERSAM.

When explaining the reasons for this increase in mortality, the authors emphasize that it is necessary to take into account the risk behaviors that people with ADHD often present. In this sense, Dr. Josep Antoni Ramos Quiroga, head of the Psychiatry Department at Vall d'Hebron University Hospital and of the Psychiatry, Mental Health and Addictions group at VHIR and CIBERSAM researcher, states that "ADHD can make patients more prone to have challenging or risky behaviors that lead them to have more accidents". On the other hand, it is also necessary to take into account that these people have a greater tendency to have harmful habits, such as smoking or having an unhealthy diet. These habits are related to the appearance of other diseases, such as diabetes or cardiovascular pathologies, which can also contribute to a decrease in life expectancy.

The authors of this study point out that the risk of premature death also depends on the age at which ADHD is diagnosed. Thus, individuals diagnosed in adulthood have a higher mortality risk compared to people diagnosed during childhood or adolescence. "An early diagnosis is key to help us to follow up and accompany patients early to avoid their entry into a negative trajectory that could end up with a higher mortality", explains Dr. Marta Ribasés, researcher of the Psychiatry, Mental Health and Addictions group at VHIR and CIBERSAM.

"Our research provides new evidence that the genes involved in ADHD may also be related to other biological processes that influence health and lifespan", concludes Dr. Gerard Muntané.