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Depression
May Raise Risk of Alzheimer's Disease
Reuters Health
April 7, 2008
People with a history of depression, especially if it begins early in life, have an increased risk of developing Alzheimer's disease, according to a report in the current issue of the journal Neurology. The risk does not appear to be influenced by structural changes in the hippocampus or amygdala - areas of the brain affected by the disease.
The findings indicate that individuals with a history of depression are at least twice as likely to develop Alzheimer's disease than those without this history. However, depressive symptoms without a firm depression diagnosis, by contrast, did not increase the risk.
Dr. Monique M. B. Breteler at the Erasmus Medical Center is Rotterdam, and colleagues analyzed data on 503 subjects, ages 60 to 90 years, who were enrolled in the Rotterdam Scan Study, a population-based study.
Depressive symptoms were evaluated using the Center for Epidemiologic Studies Depression Scale. Hippocampal and amygdalar volumes were determined using three-dimensional MRI. The subjects were then followed for signs of Alzheimer's disease for 6 years, on average.
Overall, 88 patients reported early-onset depression (younger than 60 years old) and 46 had late-onset depression, the report indicates.
Thirty-three subjects developed Alzheimer's disease. Early- and late-onset depression increased the risk of Alzheimer's disease by 3.76-fold and 2.34-fold, respectively.
However, as mentioned, the association between depression and Alzheimer's disease was not mediated by hippocampal or amygdalar volumes in the brain. Also, depressive symptoms at the start of the trial did not affect the risk of Alzheimer's disease.
"We don't know yet whether depression contributes to the development of Alzheimer's disease or whether another unknown factor causes both depression and dementia," Breteler said in a statement. "We'll need to do more studies to understand the relationship between depression and dementia."
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