title: Evaluating the impact of cannabis use on thalamic connectivity in youth at clinical high risk of psychosis.
abstract: BACKGROUND
  Disruptions in thalamic functional connectivity have been observed in people with schizophrenia and in youth at clinical high risk (CHR) of psychosis. However, the impact of environmental risk factors for psychosis on thalamic dysconnectivity is poorly understood. We tested whether thalamic dysconnectivity is related to patterns of cannabis use in a CHR sample.
  
  
  METHODS
  162 CHR and 105 control participants were assessed on cannabis use severity, frequency, and age at onset of first use as part of the North American Prodrome Longitudinal Study and completed resting-state fMRI scans. Whole-brain thalamic functional connectivity maps were generated using individual subjects' anatomically defined thalamic seeds.
  
  
  RESULTS
  Thalamic connectivity did not significantly correlate with current cannabis use severity or frequency in either CHR or controls. In CHR cannabis users, a significant correlation emerged between attenuated thalamic connectivity with left sensory/motor cortex and a younger age at onset of cannabis use. CHR who used cannabis before age 15 did not differ on thalamic connectivity as compared to CHR who used after age 15 or CHR who were cannabis naïve. No group differences in thalamic connectivity emerged when comparing CHR separated by moderate/high use frequency, low-frequency or cannabis naïve.
  
  
  CONCLUSIONS
  Although a younger age at onset of cannabis use may be associated with disrupted thalamo-cortical coupling, cannabis use does not appear to be an identifying characteristic for thalamic connectivity in CHR with moderate/high use frequency compared to low-frequency users or CHR who are cannabis naïve.
authors.affiliation: Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada. labuchy@ucalgary.ca.
authors.forename: Lisa
authors.initials: L
authors.lastname: Buchy
authors.affiliation: Department of Psychology, Yale University, New Haven, CT, USA. tyrone.cannon@yale.edu.
authors.forename: Tyrone D
authors.initials: TD
authors.lastname: Cannon
authors.affiliation: Department of Psychiatry, Yale University, New Haven, CT, USA. alan.anticevic@yale.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Anticevic
authors.affiliation: Department of Neuroscience, Faculty of Science, University of Calgary, Alberta, Canada. kklyngbe@ucalgary.ca.
authors.forename: Kristina
authors.initials: K
authors.lastname: Lyngberg
authors.affiliation: Department of Psychiatry, UCSD, La Jolla, CA, USA. kcadenhead@ucsd.edu.
authors.forename: Kristin S
authors.initials: KS
authors.lastname: Cadenhead
authors.affiliation: Department of Psychiatry, Zucker Hillside Hospital, Long Island, NY, USA. cornblat@nshs.edu.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Cornblatt
authors.affiliation: Department of Psychiatry, Yale University, New Haven, CT, USA. Thomas.mcglashan@yale.edu.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: McGlashan
authors.affiliation: Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA. diana_perkins@unc.edu.
authors.forename: Diana O
authors.initials: DO
authors.lastname: Perkins
authors.affiliation: Department of Psychiatry, Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Boston, MA, USA. larry_seidman@hms.harvard.edu.
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Seidman
authors.affiliation: Department of Psychiatry, Zucker Hillside Hospital, Long Island, NY, USA. mtsuang@ucsd.edu.
authors.forename: Ming T
authors.initials: MT
authors.lastname: Tsuang
authors.affiliation: Departments of Psychology and Psychiatry, Emory University, Atlanta, GA, USA. psyefw@emory.edu.
authors.forename: Elaine F
authors.initials: EF
authors.lastname: Walker
authors.affiliation: Department of Psychiatry, Yale University, New Haven, CT, USA. scott.woods@yale.edu.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Woods
authors.affiliation: Departments of Psychiatry and Biobehavioral Sciences and Psychology, UCLA, Los Angeles, CA, USA. cbearden@mednet.ucla.edu.
authors.forename: Carrie E
authors.initials: CE
authors.lastname: Bearden
authors.affiliation: University of California, San Francisco, San Francisco, CA, USA. Daniel.mathalon@ucsf.edu.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Mathalon
authors.affiliation: Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada. jmadding@ucalgary.ca.|Mathison Centre for Mental Health Research and Education, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4Z6. jmadding@ucalgary.ca.
authors.forename: Jean
authors.initials: J
authors.lastname: Addington
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008385:Marijuana Smoking / Q000009:adverse effects*; D009044:Motor Cortex / Q000502:physiology; D062706:Prodromal Symptoms; D011618:Psychotic Disorders / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D012559:Schizophrenia / Q000209:etiology / Q000503:physiopathology; D013788:Thalamus / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult