Is phencyclidine (PCP) abuse associated with organic mental impairment?

The performance of sober (average length of abstinence = 27 months) phencyclidine (PCP) abusers on neuropsychological measures of organicity was compared to that of polydrug users who were not experienced with PCP, and to controls who were not alcohol or drug abusers. Six of 12 PCP users, five of 12 polydrug users, and none of the controls showed neuropsychological impairments. The deficits in PCP users occurred despite negative medical-neurological history, and even though the PCP group abused other drugs previously associated with neuropsychological impairment less than the polydrug group. Deficiencies in abstracting and in perceptual-motor integrative abilities were noted. The results suggest the possibility that PCP abuse might be associated with neuropsychological disturbance which persists for considerable time after PCP use ceases.