Cognitive Function in Dementia-Free Subjects and Survival in Old Age: The PROSPER Study.

BACKGROUND

Impairment in domain-specific cognitive function is associated with the increased risk of mortality. We prospectively evaluated the association of executive function and memory with the risk of long-term mortality in dementia-free older subjects. Moreover, we investigated the role of structural brain abnormalities in this association.

METHODS

We included 547 dementia-free participants (mean age 78 years, 56.5% male) from the nested magnetic resonance imaging sub-study of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). Cox proportional hazard models were used to model 10-year risk of all-cause, cardiovascular, and noncardiovascular mortality in relation to performance in executive function and memory. Moreover, we evaluated the role of total brain parenchymal volume, cerebral blood flow, white matter hyperintensity, and the presence of microbleeds and infarcts in the link between cognitive function and mortality.

RESULTS

In the multivariable model, lower performance in executive function was associated with greater risk of all-cause (hazard ratio [HR] 1.49; 95% confidence interval [CI], 1.31-1.70), cardiovascular (HR 1.69; 95% CI, 1.36-2.11), and noncardiovascular (HR 1.36; 95% CI, 1.15-1.62) mortality. Similarly, poorer performance in memory tests associated with higher risk of all-cause (HR 1.47; 95% CI, 1.29-1.68), cardiovascular (HR 1.45; 95% CI, 1.15-1.83), and noncardiovascular (HR 1.49; 95% CI, 1.27-1.76) mortality. The associations were similar in subjects with various levels of brain structural abnormalities and cerebral blood flow (all P for interaction ≫ .05).

CONCLUSIONS

Poorer performance in both executive function and memory tests associates with all-cause, cardiovascular, and noncardiovascular mortality in elderly individuals. This association is independent of cardiovascular risk factors and diseases, brain structural abnormalities, and cerebral blood flow.