Thursday, July 18, 2013

Some Cancers Linked With Reduced Alzheimer's Risk, Study Finds

There is an inverse relationship between many types of cancers and the risk of Alzheimer's disease (AD), Jane Driver, M.D., an assistant professor of aging/geriatrics at Harvard Medical School, and colleagues reported this week at the Alzheimer's Association International Conference in Boston. They analyzed health records of some 3,500,000 veterans aged 65 and older who were seen in the Veterans Administration health care system between 1996 and 2011 and who were free of dementia at baseline. The objective was to evaluate the relationship between a history of 19 different cancers, cancer treatment, and subsequent AD.

Over a median follow-up of six years, about 82,000 veterans were diagnosed with AD, and 24% of those veterans had a history of cancer. The researchers found that most types of cancer assessed were associated with a reduced Alzheimer's risk ranging from 9% percent to 51%. Reduced risk was greatest among survivors of liver cancer (51% lower risk), pancreatic cancer (44%), esophageal cancer (33%), myeloma (26%), lung cancer (25%), and leukemia (23%). Cancers that did not appear to offer a reduced AD risk, or were associated with increased risk, included prostate, melanoma, and colorectal cancers.

The researchers also found that among veterans with a cancer history, treatment with chemotherapy—but not with radiation—conferred a reduced Alzheimer's risk of 20% to 45%, depending on cancer type, with the exception of prostate cancer. So might certain types of cancer, as well as chemotherapy, help protect people from AD? It's a possibility that needs to be further explored, Driver said.

Researchers have been studying other less-traumatic factors that might confer some degree of protection from developing AD such as exercise, diet, or memory training. See Psychiatric News for details.

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