The brains of depressed individuals respond differently to pleasure-inducing stimuli, and these changes continue to affect related mechanisms even when the condition has been in remission for some time. New research emphasizes the long-lasting nature of clinical depression, further hinting at a permanent predisposition toward mood disorders in affected individuals who stand at high risk of relapse.

In a report published in the Archives of General Psychiatry, scientists have uncovered evidence of an overarching abnormality in the brain circuitry of those with a history of depression. Researchers from the National Institute of Mental Health performed experiments on 15 individuals who’d experienced periods of depression but were unmedicated and reported no related symptoms at the time of the study. A similarly sized control group was also involved. After dosing all participants with drugs designed to sap the brain of the neurotransmitters dopamine and norepinephrine, researchers performed standard PET scans to observe patterns in neurological activity.

Results demonstrated that, as predicted, all participants experienced some sort of minor mood changes when deprived of the pleasure transmitters but that those who’d been treated for depression displayed significant changes in brain activity that closely mimicked those observed in severely depressed individuals. Their ability to respond in positive ways to pleasurable stimuli also fell considerably in the period directly after taking the study. These problems were not merely ephemeral as they were clearly exhibited by PET scans revealing increased activity in neural circuits known to compromise pleasure in depressed individuals.  

Previous studies have found relapse rates among depressed patients to run as high as 50% while others have noted that regular therapy sessions can significantly curb that risk. The larger points one can draw from this study: serious depression warranting treatment and diagnosis is not a temporary state and will most likely continue to affect its victims in some way for extended periods; even cases in which serious recovery occurs, the potential for relapse remains and should be treated with regular visits to one’s therapist. Those who suspect that they’re suffering from depression should immediately seek a professional opinion, and those who’ve been through it in the past should continue taking their medication even when symptoms improve and carefully assess their own emotional states in order to address potential relapse before it becomes a serious problem. Depression is an ongoing struggle, and education can only leave you better prepared.