Long term depression can permanently alter the brain

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Is clinical depression a degenerative illness? A new study shows that in the brain, inflammation linked to depression increases over time.

A new study conducted by the Centre for Addiction and Mental Health (CAMH) in Toronto (Canada), recently published in The Lancet Psychiatry, revealed that prolonged inflammation caused by persistent depression can modify the structure of the brain over time and in a permanent way. “The results suggest that there are several stages of depression”, explains Jeff Meyer, the main author of the study.

The researchers studied the link between the volume of total distribution of the Translocator Protein (TSPO VT), a marker of activation of microglial cells -a sign of neuro-inflammation -and the duration of untreated major depression. The link between the total duration of the illness and the duration of exposure to antidepressants was also analysed.

The researchers examined a total of 25 patients presenting with depression for over a decade, 25 with depression for less than a decade, and 30 people without depression, using positron emission tomography (PET) scans, which can detect protein markers called TSPO, that the brain’s immune cells produce in response to inflammation. People suffering from prolonged depression presented with around 30% higher levels of TSPO than people with shorter periods of depression, as well as higher levels than the control group.

“There was a strong relationship between the increase in the duration of the untreated illness and higher levels of TSPO, indicating that in terms of this marker, the advanced stage differs from the early stage of this illness”, say the authors. Additionally, the illness is not static, but it evolves. This discovery could modify treatment options, offering patients therapies adapted to their particular stage of illness. It is even possible that depression could be treated as a degenerative disease, such as Alzheimers or Parkinsons, which progressively affect the brain over time.