title: Evidence for reduced cerebellar volumes in trichotillomania.
abstract: BACKGROUND
  Limited knowledge exists regarding the neurobiology of trichotillomania (TTM). Cerebellum (CBM) volumes were explored, given its role in complex, coordinated motor sequences.
  
  
  METHODS
  Morphometric magnetic resonance imaging (MRI) scans were obtained for 14 female subjects with DSM-IV diagnoses of TTM and 12 age-, education-, and gender-matched normal control (NC) participants. Parcellation was performed utilizing a recently developed methodology to measure subterritory volumes of the CBM. Regions were defined based on knowledge of the structural and functional subunits of the CBM.
  
  
  RESULTS
  As predicted, significant group differences were reported for CBM raw cortical volumes (p = .008) that survived correction for total brain volume (TBV; p = .037) and head circumference (HC; p = .011). A priori and post hoc group raw volume comparisons for CBM subterritories and functional clusters revealed many significant differences. However, most differences failed to withstand correction for total CBM volumes (TCV). Smaller volumes were consistently reported for the TTM versus NC cohorts. Total Massachusetts General Hospital Hair Pulling Scale (MGHHPS) scores were significantly inversely correlated with left primary sensorimotor cluster volumes (p = .008), with smaller volumes associated with more severe TTM symptoms.
  
  
  CONCLUSIONS
  These findings implicate the CBM in the neurobiology of TTM, with reduced subterritory volumes reported for the TTM versus NC groups.
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA. nkeuthen@partners.org
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Keuthen
authors.forename: Nikos
authors.initials: N
authors.lastname: Makris
authors.forename: John E
authors.initials: JE
authors.lastname: Schlerf
authors.forename: Brian
authors.initials: B
authors.lastname: Martis
authors.forename: Cary R
authors.initials: CR
authors.lastname: Savage
authors.forename: Katherine
authors.initials: K
authors.lastname: McMullin
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Seidman
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Schmahmann
authors.forename: David N
authors.initials: DN
authors.lastname: Kennedy
authors.forename: Steven M
authors.initials: SM
authors.lastname: Hodge
authors.forename: Scott L
authors.initials: SL
authors.lastname: Rauch
mesh_terms: D000293:Adolescent; D000328:Adult; D002525:Cerebellar Cortex / Q000473:pathology; D002531:Cerebellum / Q000473:pathology*; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011569:Psychiatric Status Rating Scales; D014256:Trichotillomania / Q000473:pathology* / Q000523:psychology