Among young adult subject applicants to a research program, those who indicated they had used marihuana scored differently than did nonusers on a battery of personality tests. More users than nonusers were found among those who showed psychiatric impairment. The use of drugs in addition to marihuana seemed to exaggerate some of the differences observed. Moreover, changing patterns of drug use/abuse were evidenced by differing personality-drug use relationships in the periods 1968 through 1969 and 1970.
Harmatz JS, Shader RI, Salzman C. Marihuana Users and NonusersPersonality Test Differences. Arch Gen Psychiatry. 1972;26(2):108-112. doi:10.1001/archpsyc.1972.01750200012003