Longer Periods of Untreated Depression Linked to More Brain Inflammation
July 31, 2018
"A 2018 study by researchers Elaine Setiawan, Sophia Attwells and colleagues reports that inflammation seems to increase with duration of untreated unipolar depression. This implies that depression may be a progressive illness, and later stage depression may require different treatments than early stage depression, such as those that directly target inflammation.The study published in the journal The Lancet Psychiatry used positron emission tomography (PET scan) to examines levels of translocator protein in the brain. Higher levels of translocator protein indicate activation of microglia, the brain’s immune cells, which can respond to trauma or injury.The study included 80 participants between the ages of 18 and 75. Ten had a history of more than 10 years of depression, ten had experienced fewer than 10 years of depression, and 30 comprised a healthy comparison group.The best predictors of high levels of translocator protein were duration of untreated major depressive disorder, total illness duration, and duration of antidepressant exposure. These three factors explained about half of the variation in translocator protein levels. Those participants whose depression went untreated for 10 years or longer had inflammation levels 29–33% higher than those whose depression was untreated for 9 years or less.Participants who had received antidepressant treatment appeared to avoid an average yearly increase in the extent of their microglial activation.