Some Types of Skin Cancer Linked to Lower Chances of Alzheimer's

A weak immune response might allow skin cancer but protect brain from inflammation, expert suggests

By Barbara Bronson Gray

HealthDay Reporter

WEDNESDAY, May 15 (HealthDay News) -- There's some good news for people who have had certain kinds of skin cancer: A new study suggests that their odds of developing Alzheimer's disease may be significantly lower than it is for others.

People who had non-melanoma skin cancer were nearly 80 percent less likely to develop Alzheimer's disease than people who did not. The association was not found with other types of dementia.

To understand the possible association between skin cancer and Alzheimer's, it is important to know that people have a combination of cells that are multiplying and others that are dying, explained study author Dr. Richard Lipton, a professor of neurology, epidemiology and population health at the Albert Einstein College of Medicine in New York City. The research was published online May 15 in the journal Neurology.

"When cell division gets out of control, we call that cancer. And when specific populations of brain cells die, we call that Alzheimer's," Lipton said. "So, there is a balance between cell division [growth] and cell death. If you have an individual with an increased risk of cell division over cell death, that may be linked to a decreased risk of Alzheimer's."

The finding was intriguing to one expert.

"It's fascinating that we can get clues about what's going on in the brain by looking at the periphery [skin]," said Terrence Town, a professor in the physiology and biophysics department at the Keck School of Medicine at the University of Southern California.

Non-melanoma skin cancer is the most common cancer in the United States; there were more than 2 million new cases in 2012, according to the U.S. National Cancer Institute.

What could be causing the possible association between skin cancer and a reduced risk of Alzheimer's?

"Either developing skin cancer is a marker for some biological process that protects against Alzheimer's or environmental factors may play a role," Lipton said. Genetics could be a factor, as could lots of outdoor physical activity and exercise, although Lipton cautioned people to avoid too much sun exposure and wear sunscreen.

Others think the link may be directly related to how the lowered immune response of skin cells in skin cancer corresponds to a similar immune response in the brain.

"This research is another piece of evidence that tells us that peripheral inflammation [in the skin] is very important in Alzheimer's disease," Town said. He thinks that people who develop non-melanoma skin cancers don't have an immune response in their skin, and thus develop skin cancers, because an immune response may be critical to fighting skin cancer. But that benefits them when it comes to developing Alzheimer's disease.

"This reduced inflammatory response that was permissive to the skin cancer was perhaps beneficial in the brain," said Town.

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