Scientists Theorize that Chronic Depression Is Linked to Brain Inflammation

A new study from the University of California, San Diego School of Medicine suggests that chronic depression is an error in a neurobiological process that can be adapted and repaired. The researchers theorize that chronic depression comes from deep-rooted mechanisms the body uses to deal with physical injury.

Athina Markou, PhD, professor of psychiatry, and Karen Wager-Smith, a post-doctoral researcher, gathered evidence from clinical, behavioral, and biological studies to create a theory they hope will change the way we think about depression. They wanted to look at a well-functioning depressive response and the biology of its functions. When they created a theoretical model of a well-functioning depressive response, they could more easily spot the differences between depressed and non-depressed individuals.

Their theory suggests that severe stress and adverse events such as losing a loved one or a job, activate neurobiological processes that physically change the brain, changing neuron shapes and connections. Some neurons die, and others grow as the brain rewires itself. This rewiring uses basic wound-healing mechanisms, but can be painful—even when it’s working well.

Markou said that it’s normal for the brain to change so that the individual can adapt and deal with their new circumstances, but problems can occur when the restructuring goes into “overdrive” or for longer periods than are necessary. Then depression becomes chronic.

The researchers said that existing views about depression are actually describing different aspects of the same alteration. But the main question is why people are affected differently—why some people deal with stress well and others don’t. This question should be further researched, the authors said.

They added that if psychological and physical pain responses share similar mechanisms, analgesics could he helpful in treating some symptoms of depression. And if chronic depression is a nueroinflammatory condition, anti-inflammatory medications could have some antidepressant effects. Some small studies have supported this, but more research needs to be done.

Source: Science Daily, New Theory Links Depression to Chronic Brain Inflammation, October 20, 2010

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