Attributes of heavy vs. occasional marijuana smokers in a college population

We sought to assess whether college students who smoked marijuana heavily were distinguishable from students who had used the drug only occasionally. We compared 45 long-term heavy marijuana smokers (individuals who had smoked daily for at least 2 years) with 44 “occasional” smokers (individuals who had never smoked more than 10 times in a month at any time in their lives), drawn from the student populations at two Boston-area colleges. Measures included a questionnaire covering a range of demographic, drug use, and subjective items; the Rand Mental Health Inventory; and both the Axis I and Axis II sections of the Structured Clinical Interview for DSM-III-R. Heavy smokers reported higher rates of use of other substances, especially hallucinogens and cocaine, and they described greater subjective impairment of memory and motivation than occasional smokers; however, on a wide range of demographic, family background, and mental health measures, the heavy smokers proved almost indistinguishable from occasional smokers. Even the heaviest college marijuana smokers exhibit few demographic or psychiatric features that distinguish them from students who smoke only occasionally.