Could Having Cancer Reduce Your Risk Of Alzheimer's?

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Source: WikimediaCommons
Source: WikimediaCommons

A "Who’s Who" of Alzheimer’s researchers are gathered in Boston this week.  The Alzheimer’s Association International Conference — a leading global forum for Alzheimer’s scientists — kicked off on Saturday, and since then has been abuzz with all sorts of thought-provoking data and ideas surrounding research, prevention and treatment.

Amongst the conference's cutting-edge dementia discussion is a particular surprising connection that was presented today: There appears to be an inverse link between cancer and Alzheimer’s.

Boston researchers at the VA Boston Healthcare System performed an extensive epidemiological study that produced the key finding that most cancers were associated with a decreased risk of Alzheimer's.  The study also found that of the nearly 3.5 million records studied, patients whose cancers were treated with chemotherapy had the greatest reduction in their risk of Alzheimer’s.

Though researchers are unsure of the reason behind the connection, the study’s findings seem to point to chemotherapy as a potential treatment for Alzheimer’s.

An Italian study published last week in the journal Neurology, produced results that revealed the same association between cancer and risk reduction for Alzheimer’s.  The unpublished Boston study has yet to undergo peer review, but its startling results have grabbed attention at the Alzheimer’s conference.  The Boston Globe ran an article today on the findings and some of the reactions of scientists on the potential new direction of Alzheimer’s research brought to light by the study.

From the Globe story:

In the latest study, by far the largest yet to establish a link, researchers at the VA Boston Healthcare System found that most types of cancer were associated with a reduced Alzheimer’s risk, with survivors of liver cancer having the most protection, a 51 percent reduced risk.

Other apparently “protective” cancers include those of the pancreas, a 44 percent reduced risk, esophagus, 33 percent, leukemia, 31 percent, lung, 25 percent, and kidney, 22 percent.
Notably, the researchers found that certain cancers apparently conferred no reduced Alzheimer’s risk, including melanoma (a cancer of the skin), prostate, and colorectal cancers. Breast cancer was not studied because there were too few cases in the database the researchers analyzed of nearly 3.5 million veterans, 98 percent of them men, who received care between 1996 and 2011.
The scientists said the reduced risk of Alzheimer’s was not simply because cancer patients die young, before they can develop the dementia.

“So if people were dying of cancer before they could get Alzheimer’s, we would have anticipated these alternative outcomes would be lower, too, but in fact they were higher,” said Dr. Laura Frain, a co-researcher on the study and a geriatrician at the VA Boston Healthcare System.

But what surprised the team was the other finding: cancer patients treated with chemotherapy enjoyed a reduced Alzheimer’s risk. They were 20 to 45 percent less likely to develop Alzheimer’s than cancer survivors who weren’t treated with chemotherapy. This effect was not seen with prostate cancer patients, though most of them do not receive chemotherapy.

The Globe also quotes Maria Carrillo, the Alzheimer’s Association’s vice president of medical and scientific relations:

“What is [chemotherapy] doing to the brain cells that we can possibly mimic and target?” Carillo said. “We think it’s time to pay attention to this as a possible treatment because this was a very strong epidemiological study.”

This program aired on July 15, 2013. The audio for this program is not available.