F19.2 Phencyclidine Dependence Syndrome

A cluster of physiological, behavioural, and cognitive phenomena in which the use of phencyclidine (PCP) takes on a much higher priority for a given individual than other behaviours that once had greater value. A central descriptive characteristic of the dependence syndrome is the desire (often strong, sometimes overpowering) to take phencyclidine (which may or may not have been medically prescribed). There may be evidence that return to substance use after a period of abstinence leads to a more rapid reappearance of other features of the syndrome than occurs with nondependent individuals.

Diagnostic Guidelines

A definite diagnosis of dependence should usually be made only if three or more of the following have been experienced or exhibited at some time during the previous year:

(a) a strong desire or sense of compulsion to take phencyclidine;

(b) difficulties in controlling phencyclidine-taking behaviour in terms of its onset, termination, or levels of use;

(c) a physiological withdrawal state when phencyclidine use has ceased or been reduced, as evidenced by: the characteristic withdrawal syndrome for phencyclidine; or use of the same (or a closely related) substance with the intention of relieving or avoiding withdrawal symptoms;

(d) evidence of tolerance, such that increased doses of phencyclidine are required in order to achieve effects originally produced by lower doses;

(e) progressive neglect of alternative pleasures or interests because of phencyclidine use, increased amount of time necessary to obtain or take the substance or to recover from its effects;

(f) persisting with phencyclidine use despite clear evidence of overtly harmful consequences, such as depressive mood states consequent to periods of heavy substance use, or drug-related impairment of cognitive functioning; efforts should be made to determine that the user was actually, or could be expected to be, aware of the nature and extent of the harm.

Narrowing of the personal repertoire of patterns of phencyclidine use has also been described as a characteristic feature.

It is an essential characteristic of the dependence syndrome that either phencyclidine taking or a desire to take phencyclidine should be present; the subjective awareness of compulsion to use drugs is most commonly seen during attempts to stop or control substance use.