Alzheimer’s and Cancer Rarely Strike Together

A recent study published in the journal Neurology, contains evidence supporting the theory that cancers and neurological disorders are less likely to occur together. Theories and studies have been growing the past several years when researchers first noticed patients with Parkinson’s disease are affected by cancer less often. More recently a study contained evidence that people with multiple sclerosis have fewer tumors.

Lead author Dr. Catherine M. Roe and Dr. Maria Behrens evaluated data on more than 3,000 people age 65 and older. At the beginning of the study, 164 people had been diagnosed with Alzheimer’s and 522 with cancer. During the study 478 developed dementia and 376 developed invasive cancer. During the study, which monitored dementia for an average of 5.4 years and 8.3 years for cancer, showed those with Alzheimer’s at the start of the study were 69 per cent less likely to be hospitalized for cancer. Additionally, Caucasian people who had cancer when the study began were 43 per cent less likely to develop Alzheimer’s later.

The authors concluded, “ If there truly is an inverse association, it gives us one more way of finding out what’s going wrong in both cancer and Alzheimer’s, and that could lead us to new ways to treat either condition.”

One criticism of the study by Professor Clive Ballard, of the UK’s Alzheimer’s Society, is the possibility that Alzheimer’s could mask the symptoms of cancer and vice versa. In rebuttal Dr. Roe says, “If the decrease chance of cancer diagnosis was simply due to the fact that physicians don’t notice cancer in people with dementia, the decrease should have shown up for both the Alzheimer’s patients and those with vascular dementia, but the drop in cancer risk was only seen in those with Alzheimer’s.” Dr. Roe and Dr. Behrens plan to do a larger study investigating if Alzheimer’s disease is more strongly linked to specific cancers and how large or small that effect has on Alzheimer’s risk.