The Link Between Cancer and Dementia


Researchers have found a link between cancer and dementia. People all over the world are living longer than ever before. While this is obviously a good thing, the downside is that these extra years often come with age-associated disorders. Cancer and dementia are two diseases that increase with age, but they don’t come together.

Cancer and dementia don’t come together

Alzheimer’s disease is the most common cause of dementia. According to Jim Ray, head of research for the Neurodegeneration Consortium at MD Anderson, people with a history of cancer are less likely to get Alzheimer’s. And people with Alzheimer’s are less likely to get cancer. Several other studies have come to the same conclusion: cancer survivors have a relatively lower risk of developing dementia. Why is that?

Reasons that cancer and dementia don’t come together

One clue could be in the way that these diseases work. They work in very different ways. With dementia, cells that are supposed to remain alive die out. With cancer, things work the opposite way: cells multiple and do not die out. So it looks like the mechanisms that allow cancer cells to grow and spread may, in the brain, protect cells from dying.

A research team at the University of California, San Francisco School of Medicine may have an answer. Professor Maria Glymour focused on an enzyme called PIN1. The activity of the enzyme is enhanced in cancer, but decreased in Alzheimer’s. So what does this enzyme do? Plenty of things.  Among others PIN1 probably prevents the buildup of abnormal proteins in the brain that are the hallmark of Alzheimer’s.

A research team at the National Center for Biotechnology Information, has come up with a different observation. Obesity is a shared risk factor for both cancer and Alzheimer’s. Researchers notes that fat cells produce many active substances, including leptin and adiponectin; leptin has cancer stimulating and AD inhibiting properties, while adiponectin can inhibit cancer but stimulate AD.

Memory in the long term

But there’s more to it. Even before their diagnosis, older adults who go on to develop cancer have an edge when it comes to memory performance.
Among the older Americans who were tracked for 16 years, those who developed cancer typically had sharper memory skills — both before and after the diagnosis — than those who remained cancer-free.

Researchers said that cancer patients do typically see a sudden worsening in their memory for a short time. An estimated 75% of cancer patients have some level of cognitive impairment (memory loss, attention problems, etc.). Chemotherapy works by killing cancer cells by targeting fast-dividing cells, and in most cases, kills off some healthy cells along the way, including nerve cells in the brain. But afterward, their rate of memory decline continued at the same pace as before the diagnosis — which meant they maintained an advantage over cancer-free older adults.

The more researchers discover about the link between cancer and dementia, the more hope  we have for improving the quality of life for the elderly.


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