Researchers at the Netherlands University of Neurology in Amsterdam have found a link between depression and the brain’s immune system. As it turns out, it is less active in people with depression. The results of the research have been published magazine Biological Psychiatry.
Microglial cells maintain the contact points between neurons and thus help them communicate effectively with each other. In addition, microglia also act as the brain’s immune system.
Previous research has shown that depression is associated with chronic inflammatory diseases such as rheumatism, inflammatory bowel disease, and multiple sclerosis. These results suggest that brain inflammation may play a role in depression.
However, it turned out that this was not the case. The authors of the new study examined brain samples from people with depression after their deaths. Contrary to expectations, microglial cells near neurons showed reduced activity, indicating the absence of inflammation.
“During the study, we used tissue immediately after death to isolate microglia and compare them in depressed people and the control group. We observed abnormal microglia in the first group, and the greatest abnormalities were observed in patients who were depressed just before death,” the authors said.
Interestingly, the abnormalities were only seen in the gray matter of the brain. This suggests a possible interaction between microglia and structures found in gray matter: neurons and synapses.
“The proteins CD200 and CD47 are found in brain cells and synapses. They interact with microglia. “We found that the level of these proteins increased, which led to suppression of microglial cells,” the authors said.
In the future, scientists will try to find out what the consequences of inactive microglia are. The results of their work will help find new ways to treat depression.