Genes, the hippocampus, and depression

Article: Genes determine traces that stress leaves behind on brains

Our individual genetic make-up determines the effect that stress has on our emotional centers, researchers have found. Not every individual reacts in the same way to life events that produce the same degree of stress. Some grow as a result of the crisis, whereas others break down and fall ill, for example with depression. The outcome is determined by a complex interaction between depression gene versions and environmental factors.

The hippocampus is a switching station in the processing of emotions and acts like a central interface when dealing with stress. It is known to react very sensitively to stress. In situations of stress that are interpreted as a physical danger ('distress'), it shrinks in size, which is a phenomenon observed commonly in patients with depression and one which is responsible for some of their clinical symptoms. By contrast, positive stress ('eustress'), of the kind that can occur in emotionally exciting social situations can actually cause the hippocampus to increase in size.

"People with the three gene versions believed to encourage depression had a smaller hippocampus than those with fewer or none of these gene versions, even though they had the same number of stressful life events," says study leader Lukas Pezawas, describing the results. People with only one or even none of the risk genes, on the other hand, had an enlarged hippocampus with similar life events.

In a previous article posted below, it was noted that 30-40% of a person's risk for depression is genetic. That means that 60-70% of that risk is environmental, also known as "nurture." While some people seem to be "hard-wired" for depression, the 60-70% factor allows for personal choice.

Major factors "protective" against suicide are strong familial and religious relationships. These are free will choices that anyone can make to help protective themselves from suicide, if not from suicidal thoughts.


The depressive thoughts can fight these choices, but they do not have to dominate. There have been articles published recently about how psychiatrists can re-train peoples' thought patterns to overcome some of this thinking.