New Insights All mental disorders are based on a common molecular foundation

Schizophrenia, Bipolar Disorders and Co: Mental Illnesses with a Common Basis

As researchers have now found, mental illness can have important molecular similarities that are not reflected in the current diagnostic categories. The new findings could in the long term contribute to improving the diagnosis and therapy of affected patients.

Mental illnesses are widespread

According to health experts, every fourth person suffers from a mental disorder such as depression at some point in their lives. Scientific research has shown that we all have the facilities in it for us. A new study has now gained more insight into the causes of such diseases.

A recent study found that psychiatric disorders are likely to have important similarities at the molecular level that are not reflected in current diagnostic categories. (Image: Photographee.eu/fotolia.com)

Psychiatric disorders share many genetic factors

As the University of Bonn reports in a recent communication, psychiatric disorders such as schizophrenia and bipolar disorders are more common in the family.

Scientists of the Brainstorm Consortium with the participation of human geneticists of the University Hospital Bonn have now examined in a study the genetic relationships between these disorders and other diseases of the brain in a system that far exceeds the previous work on this topic.

The international team of scientists concluded that psychiatric disorders share many genetic factors, while neurological disorders such as Parkinson's or Alzheimer's appear more distinct in their genetic foundations.

Important similarities at the molecular level

Now published in the journal Science, the study addressed the question of how genetic variation is related to the development of brain diseases.

The results suggest that psychiatric disorders are likely to have important similarities at the molecular level that are not reflected in current diagnostic categories.

According to the data, international consortia for the study have pooled their data to examine the genetic patterns of 25 psychiatric and neurological disorders.

"This large-scale study was only possible through the worldwide collaboration of various researchers in the field of psychiatric and neurological diseases," says Prof. Dr. med. Markus Nöthen, Director of the Institute of Human Genetics at the University Hospital Bonn.

"It is currently one of the largest genetic studies in patients and controls worldwide." More than 500 scientists worldwide collaborated on the large-scale study, including seven at the Bonn Institute of Human Genetics.

Far-reaching genetic overlaps

Since every single genetic variant only makes a small contribution to the pathogenesis, the analyzes required large samples in order to reliably separate signals from the noise.

Using genome-wide association studies on a total of 265,218 patients and 784,643 controls, the researchers determined the extent of genetic overlap between the individual diseases.

The Bonn researchers contributed to the study with the genome of several thousand patients with schizophrenia, bipolar disorder and depression as well as several thousand healthy controls.

The results showed extensive genetic overlaps in various mental illnesses, in particular between attention deficit / hyperactivity disorder (ADHD), bipolar disorder, severe depression and schizophrenia.

In addition, the data show a strong overlap between anorexia nervosa and OCD, as well as OCD and Tourette syndrome.

In contrast, neurological disorders such as Parkinson's and multiple sclerosis were more distinct from each other and psychiatric disorders, with the exception of migraine, which is genetically linked to ADHD, major depressive disorder, and Tourette's syndrome.

Must the clinical diagnostic criteria be revised?

According to the scientists, the pronounced genetic overlap between psychiatric disorders suggests that current clinical diagnostic criteria do not accurately reflect the underlying biology.

"The results of the study could therefore lead to the need to restructure the diagnostic categories of mental illnesses in the future," says Dr. Franziska Degenhardt, head of the working group "Genetics of schizophrenic disorders" at the Institute of Human Genetics of the University of Bonn.

For example, a single mechanism that regulates the amount of protein in the brain could affect both inattentive behavior in ADHD and impaired function in schizophrenic disorders.

"In the long term, further exploration of these genetic relationships could help improve the diagnosis and treatment of patients with neuropsychiatric disorders," Dr. Andreas Forstner, who, together with Prof. Nöthen, leads the Bonn group on affective disorders, which is involved in the study. (Ad)