Distinct subtypes of trichotillomania (TTM)/chronic hair-pulling may exist. The aim of this study was to extend an earlier analysis by our group to a larger sample of patients with chronic hair-pulling, and to assess the validity and clinical utility of several putative subtypes. Eighty patients with various putative hair-pulling subtypes were compared on sociodemographic and clinical variables. Gender and disability due to pulling accounted for a number of important differences; for example, females more commonly had earlier age of onset of pulling, less comorbidity, and more disability than males. Also, those who met DSM-IV criteria B and C of TTM appeared to have a more disabling course of illness than those who did not. These data appear to support a dimensional rather than a categorical approach to subtyping. Future work, incorporating further investigation of the role of gender and psychobiological and treatment outcomes, is needed before definitive conclusions about hair-pulling subtypes can be drawn.
In the 4th edition of the Diagnostic and Statistical Manual (DSM-IV), trichotillomania (TTM) is characterized by recurrent pulling of one's hair resulting in noticeable hair loss, tension prior to or during pulling, and pleasure, relief, or gratification when pulling, and significant impairment or distress in social, occupational, or academic functioning as a result of pulling (American Psychiatric Association, 1994). The inclusion of TTM in the DSM gave impetus to increased research on this disorder. More recently, a number of authors have suggested that TTM is a heterogeneous disorder and that there may be distinct hair-pulling subtypes or styles (e.g. Christenson and Crow, 1996, Christenson and Mackenzie, 1994, Christenson et al., 1991 and Du Toit et al., 2001a). For example, given that not all hair-pulling patients meet criteria B and C of DSM-IV, one putative subtype may be patients with or without tension beforehand and relief during/after pulling (e.g. Christenson et al., 1991 and Reeve et al., 1992). Valid subtyping may lead to improvements in our understanding of TTM and to more targeted treatments (Flessner, Woods, Franklin, Keuthen, & Piacentini, 2008).
In a previous study by our group that aimed to detail the sociodemographic and phenomenological features of 47 adult subjects with chronic hair-pulling (Du Toit et al., 2001a), 81% of whom met criteria for a DSM-IV diagnosis of TTM, possible key subtypes were identified a priori based on existing theory. For example, it has been suggested that TTM may be subtyped according to the age of onset of pulling, with patients with early-onset presenting with phenomenological and course differences compared with those with late-onset of hair-pulling (e.g. Sah, Koo, & Price, 2008). Hair-pulling in males may also differ from that in females, particularly in terms of comorbid characteristics such as tics (Christensen, Mackenzie, & Mitchell, 1994). The literature also suggests other contrasts; TTM is typically conceptualized as a behavioural syndrome whereas chronic hair-pulling is conceptualized more as a behavioural symptom with a number of pathogeneses (O'Sullivan et al., 1997). Previous research has also shown significant differences between “focused” (i.e. with a compulsive quality) and “automatic” (i.e. with decreased awareness) pulling styles (e.g. Flessner, Conelea, et al., 2008). Hair-pulling styles may also have distinct cue profiles — e.g. negative affective states may in some cases trigger hair-pulling (Mackenzie, Ristvedt, Christenson, Lebow, & Mitchell, 1995). Investigation of such contrasts has, to date, provided limited support for the existence of some of these putative subtypes of chronic hair-pulling. More specifically, it has been suggested that distinct clusters of hair-pulling-related behaviours may exist (e.g. hair-pullers with vs. those without automatic/focused hair-pulling, oral habits, and comorbid self-injurious behaviours). At the same time, it has been noted that some of these contrasts may simply reflect greater severity in hair-pulling symptomatology rather than distinct subtypes of chronic hair-pulling. However, given the small sample sizes across these studies, there may have been insufficient power to delineate such categorical subtypes of TTM.
The aim of the present study was to extend the analysis of Du Toit et al. (2001a), to a larger sample of patients with hair-pulling. We hoped to compare patients who did and did not fall into previously proposed hair-pulling subtypes, on a range of sociodemographic and clinical features (including hair-pulling symptom severity, DSM-IV Axis I comorbidity, and impact on functioning).
In summary, the data here do not strongly support any particular categorical subtyping of chronic hair-pulling. Gender and level of disability (due to pulling) may account for a number of important differences across patients; for example, females more commonly had earlier age of onset of pulling, less comorbidity, and more disability than males. Also, those who meet DSM-IV criteria B and C of TTM appear to have a more disabling course of illness than those who do not. It was also suggested that the exclusion of criteria B and C for a diagnosis of TTM should be considered for DSM-V. These data support the importance of evaluating each patient across a range of different symptoms dimensions (including automatic vs. focused hair-pulling, extent of severity/comorbidity and disability). Future work, incorporating further investigation of the role of gender and psychobiological and treatment outcomes, is needed before definitive conclusions about the relative value of categorical and dimensional approaches can be drawn.
