Is there a link between cognitive decline and decreased risk of cancer mortality?

Faster cognitive decline amongst elders without dementia has been associated with a decreased risk of cancer mortality, according to a study published on April 8 by Neurology.

While previous prospective studies have demonstrated an association between Alzheimer's disease and a reduced risk of cancer, the reasons behind this are still unknown. “Because acetylcholine stimulates cell proliferation, the association suggests that the degeneration of acetylcholine-secreting cells may have a protective role in cancer onset, as this neurotransmitter would be less available to stimulate cell proliferation,” wrote lead author Julián Benito-León, MD, PhD, of University “12 of October” in Madrid. Inflammation has also been associated between Alzheimer's disease and vascular disease, and a cytotoxic action could also eradicate cancer cells.

Using 2,627 people who were at least 65 years of age and did not have dementia at the beginning of the study, Benito-León and colleagues sought to assess whether cognitive decline in elders without dementia was associated with a decreased risk of cancer mortality.

Participants were tested for memory and thinking skills at the beginning of the study and then again three years later. They were divided into three groups: those whose scores reflected the fastest cognitive decline, those whose scores improved, and those in the middle. The participants were followed for almost 13 years.

During the study, 1,003 of the participants died, 34 percent of which were in the group with the fastest decline in thinking skills and 66 percent of which were in the other two groups. Twenty-one percent of those in the group with the fastest decline died of cancer, whereas 29 percent of those in the other two groups had a cancer-related death.

Those in the fastest declining group were 30 percent less likely to die of cancer after the results were adjusted for control factors like smoking, diabetes and heart disease.

The authors suggest the need for further studies in order to better understand the inverse association found amongst community-dwelling elders without dementia.

“We need to understand better the relationship between a disease that causes abnormal cell death and one that causes abnormal cell growth,” said Benito-León in a press release. “With the increasing number of people with both dementia and cancer, understanding this association could help us better understand and treat both disease.”