COGNITIVE CORRELATES OF LONG-TERM CANNABIS USE IN COSTA-RICAN MEN

Background: Cognitive correlates of long-term cannabis use have been e lusive. We tested the hypothesis that long-term cannabis use is associ ated with deficits in shortterm memory, working memory, and attention in a literate, westernized culture (Costa Rica) in which the effects o f cannabis use can be isolated. Methods: Two cohorts of long-term cann abis users and nonusers were studied. Within each cohort, users and no nusers were comparable in age and socioeconomic status. Polydrug users and users who tested positive for the use of cannabis at the time of cognitive assessment after a 72-hour abstention period were excluded. The older cohort (whose age was similar to 45 years) had consumed cann abis for an average of 34 years, and comprised 17 users and 30 nonuser s, who had been recruited in San Jose, Costa Rica, and had been observ ed since 1973. The younger cohort (whose age was similar to 28 years) had consumed cannabis for an average of 8 years, and comprised 37 user s and 49 nonusers. Short-term memory, working memory, and attentional skills were measured in each subject. Results: Older long-term users p erformed worse than older nonusers on 2 short-term memory tests involv ing learning lists of words. In addition, older long-term users perfor med worse than older nonusers on selective and divided attention tasks associated with working memory. No notable differences were apparent between younger users and nonusers. Conclusion: Long-term cannabis use was associated with disruption of short-term memory, working memory, and attentional skills in older long-term cannabis users.