Cognitive impairment and cancer mortality: a biological or health care explanation?

To examine whether the documented association of suboptimal cognitive function with total and cardiovascular (CVD) mortality also applies to cancer mortality and probe whether the explanation for this association is biomedical or health care related.

In a subsample of 733 participants of the EPIC-Greece cohort from Athens and surrounding area, we assessed cognitive function at age 65 or older in the period 2004-2006, using the Mini-Mental State Examination (MMSE). Incidence of cancer, mortality from cancer and CVD, and overall mortality were ascertained through active follow-up for a median of 4 years after MMSE assessment using Cox proportional hazards models.

A total of 86 participants died during follow-up. A 2-point decrease in MMSE score was associated with increase in overall (hazard ratio (HR) 1.26, 95 % confidence interval (CI) 1.11-1.43), CVD (HR 1.26, 95 % CI 1.02-1.56), and cancer (HR 1.32, 95 % CI 1.02-1.70) mortality. In contrast, there was no noticeable difference in cancer incidence associated with a 2-point decrease in MMSE score (HR 1.07, 95 % CI 0.79-1.45).

Cognitive function appears to be inversely associated not only with CVD and overall, but also with cancer mortality. Although for CVD mortality there is a biomedical explanation invoking vascular mechanisms, for cancer mortality we may need to focus on socially conditioned factors, such as compromised ability to identify early signs and suboptimal compliance to treatment. Our hypothesis-generating results need to be confirmed in larger studies, as the issue is of major importance, since cognitive decline is not uncommon among the elderly.