Researchers Pinpoint Specific Brain Cells Associated With Depression for First Time

Depression may not just be a feeling-it could be traced to specific cells deep inside the brain.

A groundbreaking study from McGill University and the Douglas Institute has uncovered that two distinct types of brain cells behave differently in people with depression. Published in Nature Genetics, the research offers one of the clearest biological explanations yet for the disorder.

Using rare post-mortem brain samples from the Douglas-Bell Canada Brain Bank, scientists applied advanced single-cell genomic techniques to analyze thousands of individual brain cells. This allowed them to map both gene activity and DNA regulation in unprecedented detail.

The findings highlight two key players. First are excitatory neurons—brain cells that help regulate mood and respond to stress. In people with depression, these neurons showed altered gene activity, suggesting disruptions in emotional processing. The second group involves microglia, the brain’s immune cells. These cells are responsible for managing inflammation, and their altered behavior points to a possible link between depression and immune system dysfunction.

Together, these changes suggest that depression is not just a psychological experience but a condition rooted in measurable biological processes. This supports a growing scientific consensus that mental health disorders involve complex interactions between brain function, genetics, and immune responses.

The implications are significant. By identifying the exact cell types involved, researchers can now explore more targeted treatments—potentially developing therapies that directly address these cellular abnormalities rather than broadly affecting the entire brain.

REFERENCE: Anjali Chawla, Doruk Cakmakci, et al.; Single-nucleus chromatin accessibility profiling identifies cell types and functional variants contributing to major depression. Nature Genetics, 2025; 57 (8): 1890 DOI: 10.1038/s41588-025-02249-4