At the start of the study, 109 people reported that they had been diagnosed with skin cancer in the past. During the study, 32 people developed skin cancer and 126 people developed dementia, 100 of those with Alzheimer's. Of the 141 people with skin cancer, only two developed Alzheimer's disease, compared to 98 of the 961 people without skin cancer.
Alzheimer's is the most common form of dementia, defined by declines in memory and other thinking abilities.
"For a long time, we didn't even know inflammation was important, a key factor in the evolution of Alzheimer's disease," said Town. "Now [this paper suggests that] we can start to think more broadly; maybe it's inflammation in the blood or the skin that might be important factors."
Although the study found an association between certain non-melanoma skin cancers and lower risk of Alzheimer's, it did not prove a cause-and-effect relationship.
Learn more about skin cancer from the U.S. National Cancer Institute.
SOURCES: Richard Lipton, M.D., Edwin S. Lowe Professor and vice chair, neurology, Albert Einstein College of Medicine, New York City; Terrence Town, Ph.D., professor, physiology and biophysics, Keck School of Medicine, University of Southern California, Los Angeles; May 15, 2013, Neurology, online
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