A Web of Interferences
The symptoms of mental disorders often overlap, so a person may exhibit characteristics of multiple diseases. Researchers are looking for biological factors that explain such overlaps.
In 2018, psychiatrist Oleguer Plana-Ripoll from the Danish University of Aarhus was struck by a puzzling fact: many people suffer from more than one mental illness at the same time. For example, they show symptoms of an anxiety disorder and depression or signs of both schizophrenia and bipolar disorder. To find out how common such multiple diagnoses are, Plana-Ripoll evaluates a medical database with entries from more than 5.9 million people who lived in Denmark between 2000 and 2016. His analysis delivers an amazing result. Each mental disorder seems to make patients more susceptible to another, no matter how varied the symptoms. "We knew that comorbidity was important, but we didn't expect to find associations for all combinations," he explains.
Plana-Ripoll's study addresses a topic that has occupied researchers for more than a century: the search for the roots of mental disorders. In order to bring this to light, they are now combing through gene variants, measurements of neuronal activity and scans of the fine anatomy of the brain, among other things. In the past ten years they have accumulated veritable mountains of data. Some old thesis must be re-evaluated. The fact that mental illnesses can be divided into cleanly separated categories such as "fear" or "psychosis" has largely been refuted. Rather, disturbances merge into one another, and there hardly seem to be any hard boundaries between them. This was also shown by the Plana-Ripoll study. Researchers are therefore increasingly looking for the biological factors underlying the spectrum of psychopathology…
Exclusive translation from Nature; © Springer Nature Limited, www.nature.com, Nature 581, pp. 19-21, 2020