Depression: An Evolutionary Byproduct of Immune System?

Matt S

Current Event Posting Number: 2

Title: Depression: An Evolutionary Byproduct of Immune System?

Topic: Science

Publication name: Science Daily

Publication Date: March 1st 2012

Length of Article: 528 Words

Depression is a very serious mental condition, and it is a widespread problem in the US today: 1 in 10 adults currently suffer from depression, and so biologists began wondering whether depression is "hard-wired" into our brains, not just a very common medical condition. Some proposed theories include that depression and behaviors linked to it can pose some sort of an evolutionary advantage. Two psychiatrists from an online journal called Molecular Psychiatry, say that the roles that depression plays in a social context can be a byproduct of evolution. They say that the immune system is much more resilient when depressed and that socially, depression is sort of a shield against harm. Andrew Miller and William Timmie say that some genetic variations promote depression because of its effect on the immune system and how it could have been used as an evolutionary strategy for survival; they have already linked genes and depression, but also that while depressed, one's body is stronger when fighting infection and diseases. For the past several years, researchers have seen links between depression and inflammation, aka "over-activation" of the immune system - they say that people with depression tend to have higher levels of inflammation, even if they're not fighting an infection. Miller says that almost all of the genetic variations that have been linked to depression turn out to affect the function of the immune system. Charles Raison, another scientist from Molecular Psychiatry, says that the fact that depression boosts the immune system means that it was a very useful tool for people and especially young children when dealing with an infection; even though it does nothing for that person's social well being and relationships. The authors also say that the psychological symptoms of depression also may have been a good evolutionary tool, that fatigue/inactivity, social avoidance and anorexia can all be seen as adaptive behaviors by someone when in need to contain an infection. Miller and Raison also share a theory about why stress is related to depression, the relationship between them comes to show that depression is a response made by the immune system to protect the body from the stress, as if the body sees it as sort of a wound or infection.

Depression has always been looked at as a mental disease/disability but this research suggests that we should look at is as a physical condition. These studies could point to the fact that many diseases that we think of as mental can turn out to be physically related to our bodies, and that they could be much more than just a brain malfunction. This also forces us to look at the causes of depression in a different way; for example stress and how it also affects us physically and not only emotionally. From now on, treatments for depression will need to take into account the physical aspect; therapy and seeing a psychiatrist may not be enough anymore. Also, if this research proves to be true, it means that we will need to look for different factors that cause depression and deal with them in a different way.