Cognitive impairment and the 10-year survival probability of a normal 62-year-old population

The predictive value of cognitive impairment together with demographic and health factors on long-term survival was evaluated. The population sample comprised 389 subjects, all 62 years old. Cognitive performances were measured using verbal, visuomotor and memory tests. Cognitive impairment was determined by comparing performances with norms derived from healthy controls. Ten years after testing, the probability of survival was 89% for the cognitively preserved subjects, 80% for those with mild impairment, and 71% for those with moderate impairment (p = 0.009). Relative risk (RR) for shortened survival was 1.7 (95% CI 0.9-3.2) for the mildly, and 2.6 (95% CI 1.4-4.8) for the moderately impaired. Perceived health problems were, as expected, related to reduced survival (p < 0.001, RR 3.6, 95% CI 2.1-6.0), and there was an association between cognitive impairment and impaired perceived health (p = 0.040). Multivariate analyses with Cox's regression models showed that cognitive impairment, in particular, impaired episodic memory had an association with survival, in addition to the expected effects. Thus, memory impairment may reflect very early signs of underlying disease, and so the findings provide predictive validity for the cognitive methods used.