title: A neuropsychological comparison of obsessive-compulsive disorder and trichotillomania.
abstract: BACKGROUND
  Obsessive-compulsive disorder (OCD) and trichotillomania (compulsive hair-pulling) share overlapping co-morbidity, familial transmission, and phenomenology. However, the extent to which these disorders share a common cognitive phenotype has yet to be elucidated using patients without confounding co-morbidities.
  
  
  OBJECTIVE
  To compare neurocognitive functioning in co-morbidity-free patients with OCD and trichotillomania, focusing on domains of learning and memory, executive function, affective processing, reflection-impulsivity and decision-making.
  
  
  METHODS
  Twenty patients with OCD, 20 patients with trichotillomania, and 20 matched controls undertook neuropsychological assessment after meeting stringent inclusion criteria.
  
  
  RESULTS
  Groups were matched for age, education, verbal IQ, and gender. The OCD and trichotillomania groups were impaired on spatial working memory. Only OCD patients showed additional impairments on executive planning and visual pattern recognition memory, and missed more responses to sad target words than other groups on an affective go/no-go task. Furthermore, OCD patients failed to modulate their behaviour between conditions on the reflection-impulsivity test, suggestive of cognitive inflexibility. Both clinical groups showed intact decision-making and probabilistic reversal learning.
  
  
  CONCLUSIONS
  OCD and trichotillomania shared overlapping spatial working memory problems, but neuropsychological dysfunction in OCD spanned additional domains that were intact in trichotillomania. Findings are discussed in relation to likely fronto-striatal neural substrates and future research directions.
authors.affiliation: Department of Psychiatry, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge, UK. src33@cam.ac.uk
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Chamberlain
authors.forename: Naomi A
authors.initials: NA
authors.lastname: Fineberg
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Blackwell
authors.forename: Luke
authors.initials: L
authors.lastname: Clark
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Robbins
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Sahakian
mesh_terms: D000328:Adult; D000339:Affect; D001288:Attention; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000175:diagnosis / Q000523:psychology; D007266:Inhibition, Psychological; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000523:psychology; D009949:Orientation; D010364:Pattern Recognition, Visual; D011340:Problem Solving; D011597:Psychomotor Performance; D011930:Reaction Time; D012660:Semantics; D013223:Statistics as Topic; D014256:Trichotillomania / Q000175:diagnosis* / Q000523:psychology; D014706:Verbal Learning