Skin cancer may be linked to lower risk of Alzheimer's disease

The study involved 1,102 people with an average age of 79 who did not have dementia at the start of the study. The participants were followed for an average of 3.7 years. At the start of the study, 109 people reported that they had skin cancer in the past. During the study, 32 people developed skin cancer and 126 people developed dementia, including 100 with Alzheimer's dementia.

People who had skin cancer were nearly 80 percent less likely to develop Alzheimer's disease than people who did not have skin cancer. Of the 141 people with skin cancer, two developed Alzheimer's disease. The association was not found with other types of dementia, such as vascular dementia.

Study author Richard B. Lipton, MD, of Albert Einstein College of Medicine in Bronx, NY, and a Fellow of the American Academy of Neurology, said the reason for this possible protective effect of skin cancer is not yet known. "One possible explanation could be physical activity," he said. "Physical activity is known to protect against dementia, and outdoor activity could increase exposure to UV radiation, which increases the risk of skin cancer."

Lipton said biological factors including genetic factors likely also play a role, as physical activity does not reduce the risk of Alzheimer's disease to the extent found in the link between skin cancer and Alzheimer's disease.

The findings do not mean that people should stop taking measures to avoid skin cancer, Lipton said. "People should continue to wear sunscreen, avoid the sun during midday and wear clothing to protect their skin," he said. "The hope is that these results help us learn more about how Alzheimer's develops so we can create better preventive methods and treatments."

The study was supported by the National Institute on Aging, Einstein Aging Study, and National Cancer Institute, Albert Einstein Cancer Center.