A longitudinal study of marijuana effects

One hundred regular marijuana users volunteered to be extensively interviewed in 1968-1970, and 97 were located and reinterviewed 6 to 8 years later. As part of each interview the subjects filled out a checklist review of 105 effects of marijuana. This report focuses on the differential patterns of effects found at the two time intervals. Scores on groupings of items were examined for changes over time. Reports of sensory and hallucinatory items dropped substantially. Reports of appetite effects, sex effects, and intoxication effects on sleep remained stable. Reports of cognitive effects, mood effects, and aftereffects on sleep appeared to be shifting from desirable to undesirable, with the frequency of desirable effects dropping while frequency of undesirable effects remained the same.