The authors report a study of electroencephalographic (EEG) sleep
predictors of two-year mortality in 26 elderly patients with mixed symptoms
of depression and cognitive impairment. Patients who had died by two-year
follow-up were characterized by significantly longer rapid eye movement
(REM) sleep latencies at baseline, less robust REM sleep rebound following
all-night sleep deprivation, and baseline apnea- hypopnea indexes greater
than 3. Logistic regression analysis using the apnea-hypopnea index value
and REM latency correctly predicted 77% of survivors and non-survivors.
Survival time following initial measurements was significantly correlated
with REM sleep time (r = 0.78, p less than .02) and duration of first REM
sleep period (r = 0.75, p less than .02). The authors speculate that
changes in these predictor variables may indicate impairment in the
cholinergic control of cognitive function, REM sleep, and respiratory
function.Abstract Teaser