Can Cancer Cancel Alzheimer's?

Alzheimers risk lessened in some cancer survivors

(RxWiki News) Alzheimer's disease is the most common type of dementia. Alzheimer's is not a normal part of aging, although it typically develops in later adulthood. Research is ongoing to find causes and cures for Alzheimer's, including links between Alzheimer's and other diseases. 

Prior studies had found a link between cancer and Alzheimer's, suggesting that one disease might protect against the other.

A new study presented at the July 2013 Alzheimer's Association International Conference showed that a history of certain types of cancer and chemotherapy was associated with a decreased risk for Alzheimer's disease.

The cause of this relationship is unknown. More research is needed to find out the reasons for this risk reduction.

"Discuss memory loss with your doctor."

Laura Frain, MD, from VA Boston Healthcare, and colleagues conducted this study to look at the relationship between cancers, cancer treatments and Alzheimer's disease.

Two prior studies had noted that cancer survivors were less likely to develop Alzheimer's. For this study, the researchers also wanted to see if different types of cancer were associated with a lower risk for Alzheimer's.

The researchers reviewed health records from the VA healthcare system of patients between 1997 and 2011. They reviewed the health records of 3,499,378 veterans over 65 years of age. All veterans included in this review had never been diagnosed with or treated for dementia when they were seen for the first time.

The study followed up to see how many of the veterans developed Alzheimer's disease. At follow-up about five years later, 82,028 veterans had been diagnosed with Alzheimer's.

Of the veterans with Alzheimer's, 24 percent had a cancer history, and 76 percent never had cancer.

The study looked at 19 types of cancer. The researchers found that most types of cancer were linked to a reduced risk for Alzheimer's disease.

  • Survivors of liver cancer had a 51 percent lower risk for Alzheimer's disease.
  • Pancreatic cancer survivors had a 44 percent lower risk.
  • Esophageal cancer survivors had a 33 percent lower risk.
  • Myeloma survivors had a 26 percent lower risk.
  • Survivors of lung cancer had a 25 percent lower risk.
  • Leukemia survivors had a 23 percent lower risk.

The research also showed that cancer survivors who had chemotherapy treatment had a lower Alzheimer's risk — 20 to 45 percent lower, depending on cancer type.

The researchers noted that radiation treatment did not similarly lower the risk of Alzheimer's disease.

Several cancers were not associated with a reduced risk for Alzheimer's disease, including melanoma, prostate cancers and colorectal cancers.

The researchers found that cancer survivors had an increased risk for other conditions such as stroke, osteoarthritis, cataracts or macular degeneration, which is a disease that causes loss of vision in senior adults.

Cancer survivors may also be at risk for other types of dementia, the study found.

It is unclear if the biological reasons that cause Alzheimer’s also prevent cancer. It is possible that cancer-causing genes protect the parts of the brain that are affected by Alzheimer's.

An additional possibility is that chemotherapy may protect the nervous system from damage from Alzheimer's.

The study authors noted that more research is needed on individual cancers and chemotherapy and their relationship with Alzheimer's disease.

Dr. Frain reported at the Alzheimer's Association International Conference that this study "...could help focus future research onto the specific pathways and treatment agents involved in the individual cancers that are associated with a reduced risk of Alzheimer's."

Dr. Frain also stated that this research could lead to new strategies to prevent and treat Alzheimer's.

This research was presented at the Alzheimer's Association International Conference, July 17, 2013, in Boston, Massachusetts.

The study was funded by the Veterans Affairs (VA) Career Development Award. The authors reported no conflict of interest.

Review Date: 
July 27, 2013