A new study has revealed a link between depression and changes in specific brain cells responsible for mood and immune functions. This discovery opens up new possibilities for developing treatments that target the biological causes of the disorder.

The research, conducted by specialists from McGill University and the Douglas Institute, showed that two types of brain cells function differently in people with depression. The results, published in the journal Nature Genetics, provide new data that could help create targeted therapeutic approaches and deepen our understanding of depression—a condition affecting more than 264 million people worldwide and remaining one of the leading causes of disability.

For the first time, researchers were able to identify exactly which types of brain cells are affected by depression by comparing gene activity with DNA regulatory mechanisms. This approach allowed for a more precise determination of where disruptions occur and which cells are involved in the process.

The study used postmortem brain samples from the Douglas-Bell Canada Brain Bank, which contains tissue from people with mental disorders and serves as a valuable resource for studying the biological foundations of mental health. Using advanced single-cell genomics methods, scientists analyzed RNA and DNA from thousands of individual brain cells. The research included samples from 59 people diagnosed with depression and 41 people without the condition.

The analysis revealed changes in gene activity in two key types of brain cells. The first type is a group of excitatory neurons involved in regulating mood and stress response. The second is a subtype of microglia, the brain’s immune cells that control inflammatory processes. In both cell types, people with depression showed different gene activity, indicating possible dysfunctions in these systems. These changes may help explain the biological development of depression.

Identifying the specific cells involved confirms the biological basis of depression and challenges outdated views that consider depression solely an emotional or psychological state. The study emphasizes that depression is associated with real, measurable changes in the brain.

Future research aims to explore how these cellular differences affect overall brain function and whether treatments targeting these cells could be more effective in the future.