SAN FRANCISCO, July 17 -- Poor-quality sleep and cognitive decline appear to go hand-in-hand among older women, but it's unclear which leads the other, investigators here suggested.
Among more than 2,400 women 65 and older who were followed for more than 15 years, those who had evidence of decline on two validated cognitive tests were significantly more likely to have poor sleep efficiency, longer sleep latency, and more time awake after sleep onset, reported Kristne Yaffe, M.D., of the University of California San Francisco, and colleagues.
Citing dementia's long preclinical period, the authors speculated that that early pathologic changes could independently increase the risk of both cognitive decline and sleep disturbances. "Alternatively," they wrote in the July 17 issue of Neurology, "cognitive decline could be associated with neuropsychiatric disturbances-such as anxiety or depression-that might affect the quality of sleep."
They studied 2,474 women enrolled in a prospective, long-term study osteoporosis study for whom data on sleep and cognitive were available. The women were community-dwelling and had no evidence of dementia either at baseline or during follow-up.