CHOLINERGIC REM INDUCTION TEST - MUSCARINIC SUPERSENSITIVITY UNDERLIES POLYSOMNOGRAPHIC FINDINGS IN BOTH DEPRESSION AND SCHIZOPHRENIA

Disinhibition of rapid eye movement (REM) sleep (e.g. shortening of RE M latency, heightened REM density) is frequently encountered in patien ts with a major depressive disorder (MDD). Administration of cholinomi metics prior to or during sleep leads to a more pronounced advance of REM sleep in depressed patients compared to healthy controls and patie nts with other psychiatric disorders. The present study tested whether the cholinergic REM induction lest (CRIT) with 1.5 mg RS 86 (an orall y acting muscarinic agonist) differentiates patients with MDD (n = 40) from those with schizophrenia (M = 43) and healthy controls (n = 36). The most pronounced shortening of REM latency after cholinergic stimu lation occurred in patients with MDD. However, a significant number of patients with schizophrenia also displayed short REM latencies (REM l atency < 25 minutes) under placebo conditions and after cholinergic st imulation. REM density measures more clearly differentiated patients w ith MDD from those with schizophrenia. It is concluded that a subgroup of patients suffering from schizophrenia displays signs of a muscarin ic receptor supersensitivity.