Depressionis so detrimental to goodhealth, it’s hard to believe that thehuman bodyhasn’t found a way, through evolution and adaptation, to eliminate it. Unless, of course, it serves a purpose. Ifdepressionitself is an evolutionary adaptation, what advantages might be found in the depressive state?
Andrew Miller, MD, Emory University, and his colleague Charles Raison, MD, University of Arizona took a closer look at the evolution ofdepression. Their new study looks at thedepression-immuno-activation combination. These scientists propose that genetic variations that promotedepressionare linked to behavioral responses that fightinfection. The two are encoded on the same genetic structure making genetic markers for inflammation a predictor of futuredepression.
Researchers have long acknowledged a link betweendepressionand inflammation. People with depressivesymptomstend to have higher levels of inflammation regardless of whether or not aninfectionis present.
Fever, fatigue/inactivity, social avoidance andanorexiaare all adaptive behaviors,symptomatic of depression, that help to containinfectionand contagion.Depressiondeveloped from this and is now hard wired to the immuno response.
Even stress can be seen as a byproduct of immune-activation as the body prepares forinfectionor anticipates a wound.Sleeplessnesscaused by illness or the need to stay vigilant protecting oneself from predators would cause an activation ofdepressionand immune system. After centuries, the two are now inextricably linked.
And it could be that medications meant to treat auto-immune diseases could also treatdepression. Miller and Raison are studying this potential now.