Daytime sleepiness and cognitive impairment in the elderly population.

BACKGROUND: Recent findings suggest that there may be a relationship between excessive daytime sleepiness (EDS) and cognitive deficits. This study aims to determine to what extent EDS is predictive of cognitive impairment in an elderly population. METHODS: A total of 1026 individuals 60 years or older representative of the general population living in the metropolitan area of Paris, France, were interviewed by telephone using the Sleep-EVAL expert system. To find these individuals, 7010 randomly selected households were called: 1269 had at least 1 household member in this age range (participation rate, 80.9%). In addition to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and International Classification of Sleep Disorders diagnoses, the system administered to participants the Psychological General Well-being Schedule, the Cognitive Difficulties Scale (MacNair-R), and an independent living scale. RESULTS: Excessive daytime sleepiness was reported by 13.6% of the sample, with no significant difference among age groups. Compared with nonsleepy participants, those with EDS were at increased risk of cognitive impairment on all the dimensions of the MacNair-R scale after controlling for age, sex, physical activity, occupation, organic diseases, use of sleep or anxiety medication, sleep duration, and psychological well-being. The odd ratios were 2.1 for attention-concentration deficits, 1.7 for praxis, 2.0 for delayed recall, 2.5 for difficulties in orientation for persons, 2.2 for difficulties in temporal orientation, and 1.8 for prospective memory. CONCLUSIONS: Among elderly individuals in the general population, EDS is an important risk factor for cognitive impairment. A complaint of EDS by an elderly patient should signal the possibility of an underlying cognitive impairment in need of evaluation.