Older people with nonmelanoma skin cancers may be less likely to develop Alzheimer’s, according to new research published in Neurology. The link does not apply to melanoma, an aggressive, less common type of skin cancer.

Richard Lipton, MD, of Albert Einstein College of Medicine in New York City and colleagues conducted a longitudinal study with 1,100 residents over the age of 70. The adults, with no indication of dementia at baseline, were followed for an average of 3.7 years. At baseline, 109 participants reported a history of nonmelanoma skin cancer. Over the course of the study, 32 people developed skin cancer and 100 were diagnosed with Alzheimer’s dementia.

The researchers found that those who had skin cancer were 80% less likely to develop Alzheimer’s disease than those who didn’t have skin cancer. Of all the participants who had or developed skin cancer, two were diagnosed with Alzheimer’s. There was no link with other types of dementia.

Dr Lipton and colleagues offer that the nonmelanoma skin cancers may have some type of biological protective effect. They discuss physical activity as one explanation, “Physical activity is known to protect against dementia, and outdoor activity could increase exposure to UV radiation, which increases the risk of skin cancer.”

The researchers explain that biological factors most likely play a role, as physical activity doesn’t reduce Alzheimer’s risk to the extent seen in the study.  The authors don’t discuss vitamin D as a potential reason for the decreased risk of Alzheimer’s.

We have previously reported on research that found consumption of vitamin D rich food and midday sun exposure were linked to decreased risk of Alzheimer’s disease.

Source

Struck K. Does skin cancer protect against Alzheimer’s? Medpage Today. May 15, 2013.