A new theory about depression

What causes depression? Two researchers at the University of California, San Diego School of Medicine think it may be a response similar to what the body experiences when it suffers a physical injury.

According to the new theory, Science Daily reports, severe stress and adverse life events, such as losing a job or family member, prompt neurobiological processes that physically alter the brain. Neurons change shape and connections. Some die, but others sprout as the brain rewires itself. This neural remodeling employs basic wound-healing mechanisms, which means it can be painful and occasionally incapacitating, even when it's going well.

"It's necessary and normal so that an individual can adapt, change behavior and deal with altered circumstances," says Athina Markou, PhD, professor of psychiatry. Real problems occur only "when these restructuring processes go into overdrive, beyond what is necessary and adaptive, and for longer periods of time than needed. Then depression becomes pathological."

The theory extends findings made by other researchers that the neurobiological substrates of physical and emotional pain overlap. Just as the body's repair mechanisms for physical injury can sometimes result in chronic pain and inflammation, so too can the response to psychological trauma, resulting in chronic depression.

If the theory proves out -- and more research is needed -- the findings may have clinical ramifications. If psychological and physical pain responses share similar biological mechanisms, then analgesic agents could be useful in treating at least some symptoms of depression. Similarly, if chronic depression is proven to be a neuroinflammatory condition, then anti-inflammatory treatments should also have some antidepressant effects. Several small trials with depressed patients have already been published that support this possibility,