Abstract:
The study evaluated the auditory/verbal and visual/spatial memory of 10 cannabis-dependent adolescents and compared the results with performance of 17 subjects in two control groups. The control groups included 8 adolescent drug abusers who had not been long-term users of cannabis and another 9 adolescents who had never abused any drug. All three groups were matched by age, IQ, and absence of previous learning disabilities. Adolescents with a history of frequent alcohol or phencyclidine were excluded from entering the study. A battery of seven neuropsychololgical tests was administered initially to all subjects and a parallel test battery was administered 6 weeks thereafter. Significant differences between the cannabis-dependent group and the two control groups were obtained initially on the Benton Visual Retention Test (F[2.24]=6.04) and the Wechsler Memory Scale Prose Passages (F[2.23]=7.04). After 6 weeks of supervised abstention from intoxicants, subjects in the cannabis-dependent group showed some significant improvement on the Wechsler Memory Scale Prose Passages and on the Benton Visual Retention Test; however, the improvement failed to achieve statistical significance. It was concluded that cannabis-dependent adolescents have selective short-term memory deficits that continue for at least 6 weeks after the last use of marijuana.

Source: Richard H. Schwartz, Department of Pediatrics, Georgetown University, Medical School, Washington D.C., USA; 1989.