Effect of oral administration of Δ 9 tetrahydrocannabinol on memory, speech, and perception of thermal stimulation: Results with four normal human volunteer subjects. Preliminary report

Abstract

Several groups of workers have recently demonstrated that marihuana has a deleterious effect on memory. 1 Weil and Zinberg 2 postulated that marihuana may affect speech by interfering with retrieval of information from immediate memory storage in the brain. Employing subjective rating scales, the judges in their experiment could readily distinguish transcripts of speech produced under the influence of marihuana from control transcripts. However, no quantitative correlate of these reliable clinical judgments could be detected in the transcripts themselves. Abel 3 has studied the effect of marihuana on memory quantitatively using measures derived from signal-detection theory. He demonstrated that marihuana did not affect retrieval of information in memory when the method of free recall was used, but did affect recognition processes such that subjects were less able to discriminate between items that had been presented previously and items that had not appeared a short time before. In these studies, however, marihuana was administered by the smoking of marihuana cigarettes of undetermined tetrahydrocannabinol content, and subjective selfrating by the volunteers was relied upon to determine the magnitude of drug effect. In addition, no studies of speech were incorporated in this work. Marihuana has also been described as an analgesic, both anecdotally in man and with quantitative animal studies. 4 No quantitative measures of the analgesic potency of the agent in man have been reported. We now report quantitative measures of speech, memory, and thermal perception made simultaneously in the Same subjects functioning under the influence of a fixed, orally administered dose of pure Δ 9 tetrahydrocannabinol.