The incremental validity of criteria B and C for diagnosis of Trichotillomania in children and adults

DSM-IV-TR diagnostic criteria for Trichotillomania (TTM) specify that hair pulling (criterion A) be associated with tension prior to pulling (criterion B) and relief, pleasure, or gratification while pulling (criterion C). However, research suggests that the phenomena described by criteria B and C may not apply to all who engage in repetitive hair pulling. The current study explored the incremental validity of criteria B and C in children and adults. Participants from the Child and Adolescent Trichotillomania Impact Project (CA-TIP; n=238) and the Trichotillomania Impact Project (TIP; n=1659) were grouped according to diagnostic criteria endorsed: (1) absence of criteria B and C, (2) presence of criterion B or C (but not both), and (3) criteria B and C. Groups did not differ on measures of TTM severity; automatic pulling; depression; age of onset; and social, interpersonal, and academic functioning. Differences included lower focused pulling scores in group 1, higher anxiety scores in group 3 children, and greater pulling severity in group 3 adults. The results obtained suggest that criteria B and C add little differential information to the overall clinical picture of TTM. Intervention and research should give equal attention to all who present with hair pulling causing marked distress/impairment.