Association between sleep quality and cognitive impairment among Chinese nonagenarians/centenarians.

PURPOSE

The authors examined the individual association between sleep quality and cognitive function among the very elderly.

METHODS

The present study analyzed data from a survey that was conducted on all residents aged 90 years or older in a district; there were 2,311,709 inhabitants in 2005. Cognitive function and sleep quality were measured using the 30-item Mini-Mental State Examination and the Pittsburgh Sleep Quality Index, respectively.

RESULTS

The subjects included in the statistical analysis were 216 men and 444 women. Subjects with poor sleep quality had significant lower cognitive function scores (P = 0.007) and higher prevalence of cognitive impairment (P = 0.035). Subjects with cognitive impairment had longer sleep latency (P < 0.0001) and lower sleep efficiency percentage (P = 0.006) and more likely reported with poor quality (P = 0.035). Multiple logistic regressions showed that poor sleep quality was a risk factor for cognitive impairment (unadjusted odds ratio, 1.719; 95% confidence interval, 1.138-2.597; adjusted odds ratio, 1.759; 95% confidence interval, 1.012-3.057).

CONCLUSIONS

Among longevity Chinese, there is an association between sleep quality and cognitive function, and cognitive impairment is associated with poor quality, longer sleep latency, and lower sleep efficiency percentage.