Neuropsychological Effects of Chronic Cannabis Use on the Memory and Intelligence of Adolescents

Fifteen marijuana-dependent adolescent abusers (mean age = 16.9 years) were administered the full Wechsler Memory Scale-Revised and Wechsler Adult Intelligence Scale-Revised. Subjects had no history of other substance or alcohol abuse or dependence, cerebral trauma, psychiatric or nerological disorders. They had been abstinent form marijuana for an average of 27 days, and the majority of them were given urine tests to verify their abstenence. Comparisons among intelligence and memory indices revealed serveral significant findings that are consistent with the pattern produced by cerebral dysfunction. Specifically, memory indices were significantly reduced in relation to both intellectual function and attentional ability. In contrast, intelligence was in the normal range and unchanged relative to the estimated premorbid level. This profile is a characteristic finding in patients who are recovering form chronic impairment of memory function

Identification of Malingered Head Injury on the Wechsler Memory Scale-Revised

39 head-injured outpatients were compared with 39 age-matched Ss who were instructed to malinger head trauma symptoms on the Wechsler Memory Scale—Revised (WMS—R) and Wechsler Adult Intelligence Scale—Revised (WAIS—R). Head-injured Ss were selected who were not involved in litigation or pursuing a Worker\u27s Compensation claim. Groups did not differ significantly on IQs or memory indexes. Discriminant function analyses based on the WMS—R subtests and indexes were able to accurately classify 91% and 83% of the cases, respectively. Decision rules were cross-validated on published data from several independent studies and statistically by means of the jackknife procedure. Head-injured Ss appear to show a pattern of WMS–R scores that can be discriminated from the profile produced by individuals who attempt to malinger head trauma symptoms