A study released Monday shows military veterans treated for most common forms of cancer had lower rates of Alzheimer's disease, leading some to speculate that some cancers and chemotherapy may reduce the risk of developing Alzheimer's.
The study of 3.5 million veterans found an inverse relationship between Alzheimer's and most types of cancer. "More than 82,000 of the veterans developed Alzheimer's during the five years of the study, 24% of whom were previously diagnosed with cancer. When compared with projections for the general population, the risk of Alzheimer's was 51% lower than expected in liver cancer, 25% reduced in lung cancer and 13% lower in leukemia, according to the research. Other cancers' reduced risks seen in the study: pancreatic, 44%; esophageal, 33%; kidney, 22%; myeloma, 16%; lymphoma, 19%; head and neck, 15%.
The study's author explained at an international Alzheimer's Association conference that prostate cancer and melanoma did not show the same correlation, but that may be because those types of cancer are typically found by screenings and much earlier than other forms that are detected through symptoms.
According to a USA Today article: "There was no significant correlation between Alzheimer's and colorectal, bladder, stomach, genital, thyroid, sarcoma or brain cancer. Cancer patients who had chemotherapy lowered their Alzheimer's risk by 20%-45% for all cancers except prostate, the study showed. (Melanoma patients aren't typically treated with chemo.)"
Lead researcher Jean Driver said the extra protection afforded by chemotherapy may come from the chemicals preventing brain cells from dividing, which is characteristic of Alzheimer's. But no one should consider undergoing chemotherapy as a preventative measure.
Another study discussed at the conference, which runs through Thursday, involved diabetic patients and Alzheimer's. People who take the drug Metformin reported fewer instances of Alzheimer's than those taking other diabetes medications, including Sulfonylurea.
Though both research teams cautioned that more investigations are needed, the idea that some medications may better protect against Alzheimer's is promising in finding a way to developing drugs specifically to reduce the risk of developing the debilitating brain disease.