Abstract
The psychological effects of chronic heavy use of Cannabis sativa were studied in a population of normal adult Jamaican males. Users had been daily consumers of the drug for a minimum of 10 years; Controls were subjects who had neither current nor past experience with the drug. Subjects were matched for age, sex, social class, alcohol use, level of general information (“intelligence”), education, and modernity. Three groups of objective psychological tests were administered, in addition to a questionnaire. The first group of test concerned physiological, sensory and perceptual-motor functioning; the second groups of tests measured concept formation and abstracting abilities; the third group was comprised of a number of tests of memory.
An initial study failed to discover any indications of User impairment. The data was studied for possible confounding factors including drug potency, literacy, motivation, and research design. A replication of the study using an improved research design led to a strong confirmation of the original findings.
It was suggested that heavy users of this drug did not show test performances indicating impairment of psychological functioning comparable to other types of organic cerebral dysfunction, nor did they show chronic changes on dimensions responsive to immediate intoxication.
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Bowman, M., Pihl, R.O. Cannabis: Psychological effects of chronic heavy use. Psychopharmacologia 29, 159–170 (1973). https://doi.org/10.1007/BF00422648
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DOI: https://doi.org/10.1007/BF00422648