Neuropsychological Assessment of Undergraduate Marihuana and LSD Users
Archives of General Psychiatry – November 01, 1974
Source: OpenAlex
Summary
LSD and mescaline users performed significantly worse than marihuana/hashish users and controls on the Trail Making Test, a key measure of cognitive flexibility. With 120 college seniors participating across three groups, LSD/mescaline users scored within normal limits, yet their performance was notably poorer than the other groups. Importantly, alcohol use did not influence these results. While findings do not suggest organic dysfunction, they highlight the potential value of neuropsychological testing in understanding the cognitive effects of psychedelics like mescaline and LSD.
Abstract
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.