People with Alzheimer's disease and mild cognitive impairment (MCI) which usually precedes it often have depression as well and some studies suggest that having a history of major depression can double the risk of developing dementia. But it is unclear whether depression is an early symptom of Alzheimer's disease or whether it actually plays a part in causing it. Researchers from Rush University Medical Center in Chicago studied 357 people who were taking part in a long-term study of the risk factors for Alzheimer's disease. Every three years the sample completed a brief questionnaire about their levels of depression and were evaluated to see whether they had Alzheimer's disease. The study found no change in the level of people's depression before, during and after their development of Alzheimer's disease suggesting that it was depression which caused people's dementia rather than vice versa. The other implication of the research is that depression does not automatically go hand-in-hand with dementia and should be treated just the same in people with Alzheimer's as those without.
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