title: Marijuana use and intoxication among daily users: an intensive longitudinal study.
abstract: BACKGROUND
  Most of the harm from marijuana use is experienced by daily users. Despite this, there has not been a detailed prospective description of daily marijuana use.
  
  
  METHODS
  We recruited daily marijuana users (n=142) by internet ads, Craigslist, flyers, etc. Participants were mostly women (58%) with a mean age of 33 and 47% were minorities. Participants called an Interactive Voice Response phone system to report marijuana and other drug use daily for 3months.
  
  
  RESULTS
  Participants averaged using marijuana 3.2 times per day. Almost all participants used multiple modes of delivery during the study. Bongs/vaporizers/pipes were the most common mode of use (45% of uses). Day-to-day variability in amount of use was relatively small. The median rating of intoxication was 3.8 on a 0-6 scale with no intoxication reported on 1% of days and severe intoxication on 24% of days. The large majority binge drank (71%) or used tobacco (73%). Fifteen during-study variables were associated with the frequency of marijuana use; running out of marijuana and social setting were the strongest correlates. Retrospective reports of "usual" use at study entry were often significantly different than daily reports of use during the study.
  
  
  CONCLUSIONS
  This is the first detailed prospective description of daily marijuana use. Most users used multiple times/day, used multiple modes to administer marijuana, were often intoxicated, and under-reported high rates of using alcohol and tobacco. The frequency of marijuana use was especially influenced by social factors. These results will help future studies better describe daily marijuana use.
authors.affiliation: Department of Psychiatry, University of Vermont, Burlington, VT 05405, United States; Department of Psychology, University of Vermont, Burlington, VT 05405, United States; Department of Family Practice, University of Vermont, Burlington, VT 05405, United States. Electronic address: john.hughes@uvm.edu.
authors.forename: John R
authors.initials: JR
authors.lastname: Hughes
authors.affiliation: Department of Psychiatry, University of Vermont, Burlington, VT 05405, United States.
authors.forename: James R
authors.initials: JR
authors.lastname: Fingar
authors.affiliation: Department of Psychiatry, Geisel School of Medicine at Dartmouth, Lebanon, NH 03766, United States.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Budney
authors.affiliation: Department of Medical Biostatistics, University of Vermont, Burlington, VT 05405, United States.
authors.forename: Shelly
authors.initials: S
authors.lastname: Naud
authors.affiliation: Department of Psychiatry, University of Vermont, Burlington, VT 05405, United States.
authors.forename: John E
authors.initials: JE
authors.lastname: Helzer
authors.affiliation: Department of Biostatistics, University of Vermont, Burlington, VT 05405, United States.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Callas
mesh_terms: D000328:Adult; D063425:Binge Drinking / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology* / Q000503:physiopathology; D008385:Marijuana Smoking / Q000453:epidemiology* / Q000503:physiopathology; D011446:Prospective Studies; D012907:Smoking / Q000453:epidemiology*
keywords: Cannabis; Drug substitution; Intoxication; Marijuana; Natural history