title: Tobacco may mask poorer episodic memory among young adult cannabis users.
abstract: OBJECTIVE
  Co-occurring cannabis and tobacco use has become increasingly prevalent among young adults, but it is not clear how tobacco use may alter the neurocognitive profile typically observed among cannabis users. Although there is substantial evidence citing cannabis and tobacco's individual effect on episodic memory and related brain structures, few studies have examined the effect of combined cannabis and tobacco use on memory.
  
  
  METHODS
  This investigation examined relationships between amount of past year cannabis and tobacco use on 4 different indices of episodic memory among a sample of young adults who identified cannabis as their drug of choice.
  
  
  RESULTS
  Results indicated that more cannabis use was linked with poorer initial acquisition, total learning, and delayed recall on the Hopkins Verbal Learning Test-Revised, but only among cannabis users who sporadically smoked cigarettes in the past year. Conversely, the amount of past year cannabis use was not associated with episodic memory performance among individuals who more consistently smoked cigarettes in the past year. These differences could not be explained by several relevant potential confounds.
  
  
  CONCLUSIONS
  These findings provide important insight into a potential mechanism (i.e., attenuation of cognitive decrements) that might reinforce use of both substances and hamper cessation attempts among cannabis users who also smoke cigarettes. Ongoing and future research will help to better understand how co-use of cannabis and tobacco affects memory during acute intoxication and abstinence and the stability of these associations over time.
authors.affiliation: Department of Psychiatry, Center for Addiction Medicine, Massachusetts General Hospital.
authors.forename: Randi M
authors.initials: RM
authors.lastname: Schuster
authors.affiliation: Department of Psychology and Institute for Health Research and Policy, University of Illinois at Chicago.
authors.forename: Natania A
authors.initials: NA
authors.lastname: Crane
authors.affiliation: Department of Psychology and Institute for Health Research and Policy, University of Illinois at Chicago.
authors.forename: Robin
authors.initials: R
authors.lastname: Mermelstein
authors.affiliation: Department of Psychology, Florida International University.
authors.forename: Raul
authors.initials: R
authors.lastname: Gonzalez
mesh_terms: D000328:Adult; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007858:Learning / Q000187:drug effects; D008297:Male; D008385:Marijuana Smoking / Q000523:psychology*; D061212:Memory, Episodic; D011939:Mental Recall / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects*; D012907:Smoking / Q000523:psychology; D012959:Socioeconomic Factors; D064424:Tobacco Use / Q000523:psychology*; D055815:Young Adult