title: A cognitive comparison of pathological skin picking and trichotillomania.
abstract: OBJECTIVE
  Pathological Skin Picking (PSP) and Trichotillomania (TTM) share overlapping comorbidity and phenomenology. The extent to which these disorders share a common cognitive phenotype, however, has yet to be examined. This study sought to compare inhibitory control processes in individuals with PSP or TTM.
  
  
  METHODS
  Thirty-one subjects with PSP (mean age 31.2 ± 12.5 years; 93.5% female), 39 subjects with TTM (mean age 35.9 ± 10.7 years; 87.2% female), and 33 matched controls (mean age 31.9 ± 9.9 years; 72.7% female) undertook cognitive assessments using the Stop-Signal Task (assessing response impulsivity) and the Intra-dimensional/Extra-dimensional (ID/ED) Set Shift task (assessing cognitive flexibility). Groups were matched for age, gender, race/ethnicity, and education.
  
  
  RESULTS
  PSP was associated with significantly impaired stop-signal reaction times but intact ID/ED cognitive flexibility compared to controls. TTM occupied an intermediate position in terms of stop-signal reaction times between controls and PSP but did not differ significantly from either group on the ID/ED Set Shift Task.
  
  
  CONCLUSIONS
  These results replicate the finding of impaired inhibitory control in PSP but suggest TTM may be heterogeneous with respect to such impairment. Future work should explore possible subgroups in TTM and whether cognitive variables are predictive of treatment outcomes.
authors.affiliation: Department of Psychiatry, University of Minnesota, Minneapolis, MN 55454, USA. grant045@umn.edu
authors.forename: Jon E
authors.initials: JE
authors.lastname: Grant
authors.forename: Brian L
authors.initials: BL
authors.lastname: Odlaug
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Chamberlain
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology* / Q000523:psychology; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000150:complications* / Q000453:epidemiology / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life; D012867:Skin; D014256:Trichotillomania / Q000150:complications* / Q000453:epidemiology / Q000523:psychology; D055815:Young Adult