title: Impact of cannabis use on thalamic volume in people at familial high risk of schizophrenia.
abstract: BACKGROUND
  No longitudinal study has yet examined the association between substance use and brain volume changes in a population at high risk of schizophrenia.
  
  
  OBJECTIVE
  To examine the effects of cannabis on longitudinal thalamus and amygdala-hippocampal complex volumes within a population at high risk of schizophrenia.
  
  
  METHODS
  Magnetic resonance imaging scans were obtained from individuals at high genetic risk of schizophrenia at the point of entry to the Edinburgh High-Risk Study (EHRS) and approximately 2 years later. Differential thalamic and amygdala-hippocampal complex volume change in high-risk individuals exposed (n = 25) and not exposed (n = 32) to cannabis in the intervening period was investigated using repeated-measures analysis of variance.
  
  
  RESULTS
  Cannabis exposure was associated with bilateral thalamic volume loss. This effect was significant on the left (F = 4.47, P = 0.04) and highly significant on the right (F= 7.66, P= 0.008). These results remained significant when individuals using other illicit drugs were removed from the analysis.
  
  
  CONCLUSIONS
  These are the first longitudinal data to demonstrate an association between thalamic volume loss and exposure to cannabis in currently unaffected people at familial high risk of developing schizophrenia. This observation may be important in understanding the link between cannabis exposure and the subsequent development of schizophrenia.
authors: Robert Ferguson Unit, Astley Ainslee Hospital, Edinburgh and Division of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh EH10 5HF, UK. kwelch1@staffmail.ed.ac.uk
authors: Killian A
authors: KA
authors: Welch
authors: Andrew C
authors: AC
authors: Stanfield
authors: Andrew M
authors: AM
authors: McIntosh
authors: Heather C
authors: HC
authors: Whalley
authors: Dominic E
authors: DE
authors: Job
authors: Thomas W
authors: TW
authors: Moorhead
authors: David G C
authors: DG
authors: Owens
authors: Stephen M
authors: SM
authors: Lawrie
authors: Eve C
authors: EC
authors: Johnstone
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000473:pathology; D000704:Analysis of Variance; D002188:Cannabis / Q000009:adverse effects*; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000473:pathology*; D008385:Marijuana Smoking / Q000009:adverse effects; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000235:genetics / Q000473:pathology*; D013788:Thalamus / Q000187:drug effects / Q000473:pathology*; D013997:Time Factors; D055815:Young Adult