The cholinergic REM sleep induction test with pilocarpine in mildly depressed patients and normal controls

Previous studies suggested that depressed patients enter rapid-eye movement (REM) sleep more quickly than normal controls following the administration of muscarinic agonists such as arecoline or RS 86. We recently reported that pilocarpine, an orally active muscarinic agonist, induced REM sleep and reduced Stage 3 & 4 (Delta) sleep in young normal volunteers. In this study we present preliminary evidence that pilocarpine had similar effects on REM latency, REM percentage, and Delta (Stages 3 & 4) sleep percentage in depressed patients and controls. Pilocarpine, however, decreased stage-4 sleep in controls more than in depressed patients. Because this group of patients were only mildly depressed at the time of the study, had a high frequency of comorbid substance abuse diagnoses, and had normal electroencephalogram (EEG) sleep patterns under placebo conditions, further studies are necessary to test the hypothesis that depressed patients show hypersensitive cholinergic REM sleep induction.