Can cancer reduce dementia risk?

Liv Gardiner

4 years ago

Your risk of developing both cancer and dementia increases as you get older. Both are fears that many Australians share. But what if developing one could help protect you from the other?

A number of studies have found that cancer survivors have a lower risk of developing Alzheimer’s disease. Researchers have suggested that some of the biological mechanisms that contribute to cancer may actually help to prevent dementia.

A 16-year study of older Americans found that both before and after diagnosis, those who developed cancer had sharper memory skills. The study, published in JAMA Network Open, periodically examined the memory function of 14,500 adults born before 1949. Over the course of the study, which ran from 1998 to 2014, 2250 of the subjects were diagnosed with cancer. In the decade prior to the cancer diagnosis, the memories of these patients declined at a rate 10.5 per cent slower than patients who did not develop cancer. While patients diagnosed with cancer experienced a notable drop in memory function immediately following the diagnosis, a short time later their rate of memory decline returned to normal.

These findings are particularly interesting to the field of research as better memory was observed in some patients 10 years before they were diagnosed with cancer. This suggests that it is not the cancer itself that provided an edge against developing dementia, but rather a biological mechanism that may improve cognition while increasing the risk of cancer.

The mechanisms that are responsible for this link may hold the key to understanding and preventing dementia. Professor Maria Glymour, senior researcher of the study at the San Francisco School of Medicine, said: “We’re really interested in understanding what [they] could be, because it might point the way to strategies to prevent dementia.”

Some theories have been developed to explain the link between cancer patients and dementia risk. One theory suggests that the mechanisms that allow cancer cells to grow may help to protect brain cells from dying.

An enzyme called PIN1 may help to prevent the build-up of abnormal proteins in the brain associated with Alzheimer’s disease. The activity of this enzyme has been found to decrease in Alzheimer’s patients, but increase in cancer patients.

While these findings may sound counterintuitive, because of links between cancer and cancer treatments damaging mental cognition, attention and memory, this study supports an existing body of research showing similar results.

Dr Olivia Okereke, director of geriatric psychiatry at Massachusetts General Hospital in Boston, said these associations had been noted in studies for years.

A larger study would need to be conducted to see if this association between cancer and dementia risk is true for all types of cancer. While there was no distinction between different cancer types found, Prof. Glymour said: “We think that might just be because there were not enough cases of different types of cancer to detect the difference.”

If further research was to find links between only certain types of cancer and dementia prevention, Prof. Glymour notes that this may give more clues about the underlying cause.

Do you believe the secret to Alzheimer’s disease could be understanding this link? How have you seen cancer impact people’s memory and cognition?

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Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.