Is clinical depression a degenerative disease? A new study shows that in the brain, depression-related inflammation increases over time.
A new study from the Center for Addiction and Mental Health (CAMH) in Toronto, Canada, published in The Lancet Psychiatry, revealed a few days ago that prolonged inflammation caused by persistent depression could alter brain structure over time and permanently. “These findings suggest that there are several stages of depression,” says Jeff Meyer, lead author of the study.
The researchers investigated the relationship between the total volume of distribution of Translocator Protein (TSPO VT), a marker of microglial cell activation – a reflection of neuroinflammation – and the duration of untreated major depressive disorder. The link with total duration of illness and duration of antidepressant exposure was also analyzed.
The researchers looked at a total of 25 patients with depression for more than a decade, 25 for less than a decade, and 30 people without clinical depression as a control group. They then measured the inflammation caused by depression using positron emission tomography (PET), which detects protein markers, called TSPOs, that immune cells in the brain produce as a result of inflammation. Those with prolonged depression had TSPO levels about 30% higher than those with shorter periods of depression, and higher levels than those in the control group.
“There was a strong relationship between increasing the duration of the untreated disease and a larger TSPO, indicating that at this marker, the chronologically advanced disease differs from the early phase of this disease,” indicate the authors. Thus the disease is not static, but evolves.
This could change management by providing patients with appropriate therapies for the stage of the disease. It is even possible that depression may be treated as a degenerative disease, such as Alzheimer’s disease and Parkinson’s disease, which progressively affects the brain over time.