Acute effects of phencyclidine (PCP) on chronic and recreational users.

Snowball sampling techniques were used to generate a sample of 200 phencyclidine users from an area with a 10-year history of extensive PCP use. Three types of users were studied: heavy chronic, light chronic, and recreational users. The extent of PCP use varied from less than twice a month for a period of 6 months to daily use for several consecutive years. Each subject participated in a structured interview which lasted an average of 11/2 h. Subjects were asked about the acute effects of PCP, and about their moods before, during, and after using PCP. Scales based on previous research were used to measure the acute effects and moods. Results showed that heavy chronic users were more likely than recreational users to feel energized by PCP, and to experience negative ideations (thoughts about suicide and death). When age was controlled for, heavy chronic users were also more likely to experience violent effects. Analysis of moods over time showed some similar patterns between heavy chronic and recreational users, as well as some striking differences. Overall, heavy chronic users reported greater mood elevations while high on PCP, and a more dramatic drop in mood after the high wore off, than recreational users. Analysis of the results by user types clarified some of the confusion about contradictory descriptions of the effects of PCP, and point to the need to continue distinguishing between user types.