SLEEP-APNEA SYNDROME IN THE ELDERLY

Sleep apnea syndrome (SAS) is a well established sleep disorder with high morbidity and mortality. Patients are most often middle-aged men. SAS occurs in at least 1% of the adult population. Several studies have suggested that SAS is extemely frequentin the elderly, its prevalence ranging from 18 to 73% in this group. However, the generalization of these results to elderly cohorts is questionable because of several limitations of these studies, including lack of standard selection criteria, variation in recording techniques, the night to night variability of sleep apnea and the use of a moderate level of sleep disordered breathing (SDB) to define SAS (5 apneas per hour). The study best designed for valid extrapolation to the whole aged population estimates the frequency of SAS at 18%. However, most of these patients reported satisfactory sleep, and epidemiologic criteria for a causal association between SAS in the elderly and cardiovascular disease have not been satisfied. The conclusions of numerous studies dealing with impairment in cognitive function and SAS in the elderly are controversial. In fact, if the diagnostic threshold is increased from 5 apneas to 10 apneas plus hypopneas per hour, elderly SAS patients have more sleep disturbances, are more depressed and have cognitive deficits as compared to normal old persons. When an appropriate diagnostic index is used, SAS in the elderly resembles SAS described in the middle-aged population. In addition, a high apnea plus hypopnea index is an ominous predictor of mortality in the elderly population, and a very high level of SDB is an extremely significant risk factor for mortality during sleep phase in these patients. This review of the epidemiologic evidence suggests that only symptomatic elderly patients need to be recorded in a sleep laboratory to diagnose and treat a sleep apnea syndrome. Epidemiologic studies including more numerous and more severely affected subjects are required to analyze the natural history of SDB in the elderly.