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Poor sleep quality associated with cognitive decline in older men

Men who experienced fragmented sleep and lower sleep efficiency were more likely to demonstrate cognitive decline, according to a recent study published in Sleep.

Study findings showed that the decline in executive function attributed to poor sleep quality was equivalent to the effect of a 5-year increase in age.

Terri Blackwell, MA, of the California Pacific Medical Center Research Institute, and colleagues collected data from 2,822 older men for whom the mean age was 76 years. Participants were enrolled in the multicenter Outcomes of Sleep Disorders in Men (MrOS Sleep) Study. For an average of 5 nights, participants wore a wrist actigraph that provided data on sleep quality and duration by tracking movement. Researchers also evaluated sleep with the Pittsburgh Sleep Quality Index (PSQI) and daytime sleepiness with the Epworth Sleepiness Scale (ESS).

The population-based, longitudinal study evaluated cognitive function using the Trail Making Test Part B (Trails B), a timed test that measures attention, sequencing, visual scanning and executive function.

Using logistic regression and random-effects models, Blackwell et al examined the association between reported sleep parameters and measured changes in cognition over time. Clinically significant cognitive decline was defined as a five-point or greater decline on the Modified Mini-Mental State examination (3MS) and a change in score on the Trails B test time in the worse decile.

After multivariable adjustment, higher levels of wake-after-sleep onset (WASO) and a higher number of long wake episodes (LWEP) and lower sleep efficiency (SE) were associated with a 1.4- to 1.5-fold increase in odds of clinically significant cognitive decline on the Trails B test. Statistical analysis of sleep predictors and cognitive measures also demonstrated the following associations:

• Study participants reporting SE <70% were 1.53 times more likely to show cognitive decline compared with those with SE ≥70% (95% CI, 1.07-2.18).
• Participants with WASO ≥90 minutes were 1.47 times more likely to show decline in comparison with participants who had WASO <90 min (95% CI, 1.09-1.98).
• Participants with eight or more LWEP were 1.38 times more likely to report decline than participants with fewer than eight episodes (95% CI, 1.02-1.86).
• Lower PSQI was associated with decline in Trails B time-sensitive cognition scores.

“It was the quality of sleep that predicted future cognitive decline in this study, not the quantity,” Blackwell said in a press release.

“With the rate of cognitive impairment increasing and the high prevalence of sleep problems in the elderly, it is important to determine prospective associations with sleep and cognitive decline,” researchers wrote.

Disclosure: See the full study for a complete list of relevant financial disclosures.