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.