Cannabis abuse effects on prepulse inhibition in patients with first episode psychosis in schizophrenia.

Deficits in prepulse inhibition (PPI) and cannabis abuse are consistently found in schizophrenia. The authors studied PPI deficits in first episode psychosis (FEP) with schizophrenia and cannabis abuse influence. Thirty-five patients with FEP and 22 control subjects were examined. Patients were divided into cannabis use disorder (CUD) (N=21) and non-CUD (N=14). Startle measures were as follows: PPI at 30, 60, and 120 msec. Patients with CUD and patients without CUD showed lower PPI at 30 msec than control subjects. At 60 msec, patients with CUD obtained higher %PPI than patients without CUD, and patients without CUD obtained lower levels than control subjects. These findings show that cannabis abuse may improve PPI in patients with FEP at some levels.