How Depression Weakens the Brain

In findings that highlight the importance of mood and stress to maintaining a healthy brain, researchers and psychiatrists say that a bout of depression may raise the risks of developing dementia later in life.

People who have experienced a major depression even once in the previous 10 years in late middle age are twice as likely as those who haven't to develop problems in concentration, memory or problem-solving ability after the age of 65, according to several large, epidemiological studies.

Depression is also associated with shrinkage of the part of the brain related to memory, research shows. And while problems with concentration, decision making and memory can be common for people going through depression, studies show a significant portion of older people won't recover their mental sharpness even if their mood recovers. They may even develop new difficulties in their thinking and memory, according to a 2006 study in the American Journal of Geriatric Psychiatry. ...

Another theory of how depression affects cognitive function involves the hippocampus -- a part of the brain related to memory. Studies show that people with more days of depression untreated by antidepressants, at any point in their lives, exhibit an average 10% reduction in volume in the hippocampus, which may result in subtle changes to their memory capabilities, according to Yvette Sheline, author of the research, which was funded by the National Institute of Mental Health and published in the American Journal of Psychiatry. There is no such effect from days of treated depression. The findings suggest that shrinkage may be prevented by antidepressant treatment, says Dr. Sheline, director of the Center for Depression and Neuroimaging at the Washington University School of Medicine in St. Louis. ...

•	How Depression Weakens the Brain Mounting Evidence Suggests Even One Untreated Bout Can Raise Risk of Dementia The Wall Street Journal, Tuesday, July 3, 2007 Byline: Shirley S. Wang