Scientists are learning more and more about the physical signs of depression. Previous studies have shown that persistent depression is linked to a shrinking of the hippocampus, the part of the brain involved in forging new memories. Now, a study published in The Lancet Psychiatry has found that years of depression can leave a telling mark on the brain.
In patients with long bouts of untreated depression lasting 10 years or more, the researchers detected significantly higher levels of inflammation compared to those who had not experienced the condition for as long or at all.
“Greater inflammation in the brain is a common response with degenerative brain diseases as they progress, such as with Alzheimer’s disease and Parkinson’s disease,” Jeff Meyer, senior author and Canada Research Chair in the Neurochemistry of Major Depression, explained in a statement.
Depression wouldn’t be categorized as a degenerative brain disease like Alzheimer’s or Parkinson’s, but the results here do seem to suggest that, for many, it is a progressive (rather than a static) condition. If this is true, it could have some important implications when it comes to treatment.
For the study, researchers from Toronto’s Centre for Addiction and Mental Health (CAMH) measured translocator proteins (TSPO), which are produced by the brain’s microglia when activated.
The microglia make up 10 to 15 percent of brain cells and are responsible for controlling the immune response in the central nervous system (CNS), removing dead neurons and cellular debris a bit like a vacuum cleaner might clean up dirt. They play an important role in the brain’s healthy inflammatory response to trauma, but can also cause excessive neuroinflammation.