Marijuana: An analysis of storage and retrieval deficits in memory with the technique of restricted reminding

Abstract

A simple word list learning technique which has previously been shown to be useful clinically in evaluating disordered memory in organic patients, was employed to assess the effects of marijuana on storage and retrieval processes in memory. Twelve male subjects were administered marijuana and placebo in two separate sessions separated by a one week interval. Each subject served as his own drug control. Fifteen min after smoking a 500 mg marijuana cigarette containing 2.1% Δ 9 - THC or a placebo cigarette, each subject presented with a 30-item word list and then required to recall it in writing. Half of the subjects in the first session recalled one list while the other half recalled a second similarly constructed list. The lists were reversed during the second session. Following the initial recall test, onlythose words not recalled were presented again. Presentation of a given word continued only until an item was recalled once. There were 12 recall trials. This method termed restricted reminding allows for the simultaneous evaluation of storage and retrieval without confounding due to continuous presentation. The critical data were the number of items recalled without presentation following initial recall. Results indicated that marijuana produced a slower rate of acquisition of items into storage in comparison to placebo although the same number of items were eventually stored under both conditions. The drug appeared to exert its most deleterious effect on the retrieval of information from long term storage.