title: Age at onset in trichotillomania:clinical variables and neurocognitive performance.
abstract: OBJECTIVE
  Trichotillomania (TTM), or compulsive hair pulling, is a common psychiatric disorder characterized by psychosocial impairment and reduced quality of life. The aim of this retrospective study was to characterize the impact of age at TTM onset on clinical variables and neuropsychological function using a variety of clinical and neurocognitive measures.
  
  
  METHODS
  The study sample included 98 adult treatment-seeking individuals with a DSM-IV diagnosis of TTM. Correlates were explored by grouping participants into childhood-onset (onset at ≤ 11 years old, n = 42) or later-onset (≥ 12 years old, n = 56) TTM and via linear regression. All subjects underwent a semistructured clinical interview with a psychiatrist and completed a variety of paper-pencil tests regarding TTM severity and quality of life. A subset (n = 44) of subjects underwent neurocognitive testing assessing motor inhibition and set-shifting compared to a sample (n = 27) of age- and gender-matched healthy controls. Data were collected from September 2006 through July 2011.
  
  
  RESULTS
  Postpubertal age at onset was significantly associated with greater TTM symptom severity. Clinically, the later-onset group pulled their hair for a significantly greater amount of time daily (P = .008), had higher clinician-rated TTM severity on the Clinical Global Impressions-Severity of Illness scale (P = .042), and had higher patient-rated severity on the Massachusetts General Hospital Hairpulling Scale (P = .022) compared to healthy controls. On the neurocognitive tasks, later-onset TTM was characterized by stop-signal impairments (P = .020) and relatively spared set-shifting, consistent with previous studies in the literature. In contrast, the childhood-onset manifestation was associated with set-shifting deficits in stages of the task completed and total errors adjusted (both P < .001) but relatively spared stop-signal performance compared to healthy controls.
  
  
  CONCLUSIONS
  Results indicate that childhood-onset of TTM is common, as confirmed by the fact that 42.9% of our sample met childhood-onset criteria, and may differ neurobiologically from the prototypical later-onset form. Future neurobiological and treatment studies should measure age at onset and explore further these putative differences.Trial Registration ClinicalTrials.gov identifiers: NCT00354770 and NCT00775229.
authors.affiliation: Department of Psychiatry, Ambulatory Research Center, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Odlaug
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Chamberlain
authors.forename: Arit M
authors.initials: AM
authors.lastname: Harvanko
authors.forename: Jon E
authors.initials: JE
authors.lastname: Grant