Biological aspects of cannabis use.

In this paper the results of a multidisciplinary long term and controlled study on chronic cannabis use are critically reviewed. The first part of the study consisted of: (a) standardization of methods and identification of the experimental sample of chronic cannabis users and matched controls; (b) comparison of the two groups on a number of variables following administration of a battery of medical, psychiatric, neurophysiologic, and psychologic tests; (c) acute cannabis inhalation experiments during which the effect of cannabis preparations of various strengths and of THC-delta-9 were studied in relation to behavioral, psychologic, neurophysiologic, and psychophysiologic responses; (d) identificaiton of possible withdrawal symptoms during a 3-day abstinence period and reintroduction of hashish use. The second part of the study consisted of: (a) a controlled histochemical and electron-microscopic investigation of blood cells and sperm, aimed at revealing changes produced by cannabis at the molecular level, particularly in the cell-nuclear area; (b) a biochemical investigation of changes in biogenic amines and substances related to their metabolism and function during cannabis pre-smoking and postsmoking periods. Our findings from the first part of the study failed to distinguish users from nonusers on most of the investigated parameters. However, they provided useful information on a variety of controversial issues and revealed methodological limitations which should guide future research. Our findings from the second part of the study, although still preliminary, clearly indicate that cannabis use affects cell-nuclear metabolism and produces changes on the molecular level potentially significant for man's biologic functioning. Furthermore findings from this part of this study indicated that cannabis' acute effects in man are correlated with changes in metabolism directly related to biogenic amine biosynthesis and function. It is concluded that despite advances in recent years cannabis research has still a long way to go before providing the definitive answers to the very important questions arising from its habitual use by man.