title: Sexual Risk Behavior and Heavy Drinking Among Weekly Marijuana Users.
abstract: OBJECTIVE
  Sexual behavior that incurs increased risk for sexually transmitted infections and HIV incidence is associated with both heavy alcohol and marijuana use. Whereas detrimental effects of alcohol on increased sexual risk have been documented in event-level and laboratory studies, less is known about the combined use of alcohol and marijuana and their relative impact on sexual risk behavior. We examined the degree to which both heavy drinking and marijuana use were associated with condomless sexual intercourse with casual versus main partners in a sample of weekly marijuana smokers.
  
  
  METHODS
  Participants reported substance use and sexual activity using a 60-day Timeline Followback interview method (n = 112).
  
  
  RESULTS
  Results of generalized estimating equations indicated that both alcohol and marijuana use were independently associated with greater odds of having sexual intercourse but were not associated with greater odds of unprotected sex with a casual partner. Heavy drinking on a given day was associated with increased odds of having casual protected sex. Using both substances synergistically increased the likelihood of unprotected sex with a main partner.
  
  
  CONCLUSIONS
  Findings suggest that behaviors posing higher sexual risk (condomless intercourse or sex with casual partners) occur on days when alcohol use exceeds moderate drinking guidelines. Interventions designed to reduce sexual risk behaviors may need to specifically target heavy drinking alone or when used with marijuana.
authors.affiliation: Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.|Providence Veterans Affairs Medical Center, Providence, Rhode Island.
authors.forename: Jane
authors.initials: J
authors.lastname: Metrik
authors.affiliation: Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Caswell
authors.affiliation: Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.
authors.forename: Molly
authors.initials: M
authors.lastname: Magill
authors.affiliation: Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Monti
authors.affiliation: Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Kahler
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology / Q000523:psychology*; D003075:Coitus / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology / Q000523:psychology*; D012189:Retrospective Studies; D012309:Risk-Taking; D012725:Sexual Behavior / Q000523:psychology*; D012747:Sexual Partners / Q000523:psychology; D012749:Sexually Transmitted Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D013997:Time Factors; D047568:Unsafe Sex / Q000523:psychology; D055815:Young Adult