Q. Can depression be diagnosed by imaging the brain?
A. Although researchers have struggled to link psychiatric symptoms to specific measurable changes in the brain or body, so far there is no objective diagnostic test for depression.
But that may be about to change. Researchers are exploring measurable abnormalities in the way areas of the brain interconnect. In a report in Psychological Medicine in 2016, researchers using brain scans found a close association between a subtype of depression called melancholic depression (melancholia) and a loss of normal connections in areas of the brain related to emotions.
The pattern of connectivity linked to melancholia differed slightly from the pattern associated with major depressive disorder, suggesting that a brain scan might be used to diagnose different forms of depression.
In a study published in Nature Medicine in 2017, other researchers used MRIs to look at connections among 258 areas of the brain in 1,188 people with depression. They distinguished four distinct subtypes of depression and were then able to match specific subtypes of depression to particular symptoms.
Two subtypes were more likely to lead to fatigue, for example, while two other subtypes were linked to trouble feeling pleasure. The researchers found that one of the subtypes was three times more likely than the others to benefit from transcranial magnetic stimulation (see final question, at right)—one of the first examples of how a diagnostic test might be used to guide treatment.
This article first appeared in the UC Berkeley WellnessLetter.
Also see 'Shock Therapy' for Depression?