title: Effects of cannabis on cognitive function in patients with multiple sclerosis.
abstract: BACKGROUND
  While neuropsychological deficits have been reported in healthy individuals who use street cannabis, data in patients with multiple sclerosis (MS) are lacking. Given that MS is associated with cognitive deterioration, the aim of this study was to determine the neuropsychological effects of cannabis use in this population.
  
  
  METHODS
  Two groups, each of 25 patients with MS (cannabis users and nonusers), were administered the Minimal Assessment of Cognitive Function in MS battery of neuropsychological tests, the Hospital Anxiety and Depression Scale (HADS), and the Structured Clinical Interview for the DSM-IV Axis I Disorders (SCID-I). Group-matching and regression analysis were used to control for the effects of age, sex, education, premorbid intelligence, disability, and disease course and duration on cognitive function.
  
  
  RESULTS
  Cannabis users performed significantly more poorly than nonusers on measures of information processing speed, working memory, executive functions, and visuospatial perception. They were also twice as likely as nonusers to be classified as globally cognitively impaired. There were no between-group differences on the HADS measures of depression and anxiety or lifetime SCID-I psychiatric diagnoses.
  
  
  CONCLUSIONS
  This cross-sectional study provides empirical evidence that prolonged use of inhaled or ingested street cannabis in patients with MS is associated with poorer performance on cognitive domains commonly affected in this population. Whatever subjective benefits patients may derive from using street cannabis (e.g., pain and spasticity relief) should be weighed against the associated cognitive side effects.
authors: University of Toronto, 27 King's College Circle, Toronto, Ontario, Canada M5S.
authors: Kimia
authors: K
authors: Honarmand
authors: Mary C
authors: MC
authors: Tierney
authors: Paul
authors: P
authors: O'Connor
authors: Anthony
authors: A
authors: Feinstein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002188:Cannabis; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D003072:Cognition Disorders / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications* / Q000188:drug therapy*; D009483:Neuropsychological Tests; D008517:Phytotherapy; D028321:Plant Preparations / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
chemical_list: D028321:Plant Preparations