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Disentangling Reward Processing in Trichotillomania: ‘Wanting’ and ‘Liking’ Hair Pulling Have Distinct Clinical Correlates

  • Snorrason, Ivar1, 2, 3, 4
  • Ricketts, Emily J.5
  • Olafsson, Ragnar P.6
  • Rozenman, Michelle5
  • Colwell, Christopher S.5
  • Piacentini, John5
  • 1 New York State Psychiatric Institute, Division of Clinical Therapeutics, New York, NY, USA , New York (United States)
  • 2 Columbia University Medical Center, Department of Psychiatry, New York, NY, USA , New York (United States)
  • 3 McLean Hospital, Behavioral Health Partial Program, Belmont, MA, USA , Belmont (United States)
  • 4 Harvard Medical School, Department of Psychiatry, Boston, MA, USA , Boston (United States)
  • 5 University of California, Los Angeles, Division of Child and Adolescent Psychiatry, Los Angeles, CA, USA , Los Angeles (United States)
  • 6 University of Iceland, Department of Psychology, Reykjavik, Iceland , Reykjavik (Iceland)
Published Article
Journal of Psychopathology and Behavioral Assessment
Springer US
Publication Date
Dec 10, 2018
DOI: 10.1007/s10862-018-9712-4
Springer Nature


Trichotillomania (TTM; hair-pulling disorder) is characterized by an irresistible urge or desire to pull out one’s own hair, and a sense of pleasure when hair is pulled out. Evidence from translational neuroscience has shown that ‘wanting’ (motivation to seek a reward) and ‘liking’ (enjoyment when reward is received) are each mediated by overlapping but distinct neural circuitry, and that ‘wanting’ contributes to addictive/compulsive behaviors more so than ‘liking’. In the present study, we developed the Hair Pulling Reward Scale (HPRS), a self-report measure that consists of two subscales designed to assess (a) cue-triggered urges and appetitive motivation to pull hair (i.e., putative correlates of ‘wanting’), and (b) momentary pleasure and gratification during pulling episodes (i.e., putative correlates of ‘liking’). We administered the HPRS to 259 individuals with TTM and examined its psychometric properties. Confirmatory factor analysis supported a two-factor model reflecting correlated Wanting and Liking scales. Consistent with predictions, Wanting, much more than Liking, had robust correlations with TTM severity, impulsiveness, difficulties in emotion regulation, psychiatric symptoms, and sleep dysfunction. The results suggest that the HPRS is a psychometrically sound instrument that can be used as a symptom-level measure of reward processing in TTM.

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