Our understanding of mental illness is undergoing a major evolution, driven by recent advances in genetics. Rather than focusing solely on symptoms observed in consultation, research is now interested in the common biological foundations of several conditions. This approach could transform the clinical view of psychiatry.
An unprecedented large-scale study, published in the journal
Nature, provides key insights. By analyzing the genomic data of more than a million people with psychiatric disorders, an international consortium revealed that these pathologies share more hereditary characteristics than previously assumed. This discovery opens up perspectives for refining classifications and imagining new therapeutic approaches.
Illustration image Pexels Five genetic families redraw the psychiatric landscape
The analysis allowed grouping 14 major disorders into 5 distinct categories, based on their genetic similarities. The first family brings together pathologies with compulsive characteristics, such as anorexia nervosa and obsessive-compulsive disorder. The second includes so-called internalized disorders, mainly depression, anxiety, and post-traumatic stress disorder. Problems related to substance use form a third category.
Neurodevelopmental disorders, such as autism and ADHD, constitute the fourth group. Finally, schizophrenia and bipolar disorders, traditionally considered separate, share a large part of their genetic architecture and form a fifth distinct family. These groupings show that current diagnostic boundaries do not always reflect the underlying biological reality.
Common biological mechanisms identified
Beyond the grouping, the study linked each family to specific cellular processes in the brain. The genes associated with internalized disorders, for example, appear particularly active in oligodendrocytes, cells essential for protecting neuronal networks. For schizophrenia and bipolar disorders, excitatory neurons are mainly involved.
The researchers also mapped over a hundred regions of the genome where genetic variants simultaneously influence the risk of developing multiple disorders. One of these areas, on chromosome 11, is linked to no less than eight different conditions. These genetic "hotspots" offer prime targets for future research.
This work suggests that some of these common genetic factors act very early, during fetal brain development, while others exert their effects later. This detailed understanding of the mechanisms and their timing is important for considering preventive interventions or more targeted treatments, adapted to the biological pathways shared by several diagnoses.
Article author: Cédric DEPOND