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.
Ohayon
Maurice M
MM
Sleep Disorders Center, Stanford University School of Medicine, 401 Quarry Rd, Suite 3301, Stanford, CA 94305, USA. mrcohayon@aol.com
Vecchierini
Marie-Françoise
MF
D000368:Aged; D003071:Cognition; D003072:Cognition Disorders / Q000453:epidemiology* / Q000209:etiology; D020920:Dyssomnias / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D020178:Sleep Disorders, Circadian Rhythm / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology