Researchers from Canada have found that people with chronic depression who ultimately commit suicide have significantly fewer levels of certain supportive nerve cells in the brain compared to people with no mental health diagnosis.
For the study, the researchers examined astrocytes- a kind of support cell in the brain that distributes nutrients, keeps charged molecules in balance, and heals trauma to the brain and spinal cord. Previously, researchers found that a protein called glial fibrillary acidic protein (GFAP) isn't expressed in as high quantities by astrocytes in brains diagnosed with depression than those without.
As astrocytes that produce GFAP are a minority of the overall astrocyte population, the researchers set out to identify other features of astrocytes that may influence depression. In this case, the researchers set out to map vimentin, another kind of protein found in astrocytes. To do so, they analyzed brain tissue from 10 men diagnosed with depression who passed away from suicide. They then compared these samples with those from 10 men who died suddenly with no mental health diagnosis.
In doing so, they found that, like with GFAP-producing astrocytes, vimentin-expressing astrocytes were significantly fewer among brain tissue samples taken from men with depression than those without. Moreover, they found that men diagnosed with depression had twice as few vimentin cells than GFAP cells in the prefrontal cortex. The findings suggest that vimentin likely plays a significant role in chronic depression. How these proteins influence depression, however, and why they decline in number, remains unknown.
"The promising news is that unlike neurons, the adult human brain continually produces many new astrocytes," says senior author of the research, Naguib Mechawar. "Finding ways that strengthen these natural brain functions may improve symptoms in depressed individuals."