November 1974

Neuropsychological Assessment of Undergraduate Marihuana and LSD Users

Author Affiliations

From the Department of Psychiatry, Dartmouth Medical School, Hanover, NH.

Arch Gen Psychiatry. 1974;31(5):707-711. doi:10.1001/archpsyc.1974.01760170093015

An extended battery of neuropsychological tests was administered to three groups of college seniors (lysergic acid diethylamide [LSD]/mescaline users; marihuana/hashish users; and controls) who were matched on predrug usage intellectual and personality dimensions. The study was replicated one year later. In the combined-years' analyses, the three groups showed statistically significant differences only on the Trail Making Test: LSD/mescaline users performed within normal limits but significantly worse than either of the other two groups. Since the three groups also differed significantly in the extent of their alcohol usage, a covariance analysis was carried out that indicated that this variable did not account for the LSD/mescaline group's performance on the Trail Making Test. Inference about possible organic dysfunction cannot be drawn from these findings, but prospective neuropsychological testing might prove useful.