Personality traits and their clinical associations in trichotillomania and skin picking disorder

Trichotillomania and skin picking disorder are characterized, respectively, by recurrent pulling and picking, resulting in hair loss or skin excoriations, as well as functional impairment or distress [1]. Understanding factors that may contribute to the picking or pulling behaviors, or even assist with coping with the behaviors, may be valuable as these personality traits may add to our understanding of these disorders and contribute to the development of more effective treatments. Unfortunately, even though research on these under-recognized disorders is increasing, personality traits in people with trichotillomania and skin picking disorder have received little investigation.

Only a few studies to date have examined personality features of people with these disorders. In an early study, Stanley and colleagues [2] assessed personality traits in people with trichotillomania (n = 8) and obsessive compulsive disorder (OCD) (n = 13), and found that adults with trichotillomania were more extraverted than OCD patients (using the Eysenk Personality Questionnaire). Using the Temperament and Character Inventory, Lochner and colleagues [3] assessed 54 participants with trichotillomania and 278 with OCD and found that those with trichotillomania scored significantly higher on novelty seeking, whereas those with OCD reported significantly greater harm avoidance. In one of the few studies of skin picking disorder (n = 21), Lochner and colleagues [4] found that people with skin picking disorder scored high (compared to published normative data) on measures of reward dependence and harm avoidance, but not on novelty-seeking, using the Tridimensional Personality Questionnaire. In a study of 43 adults with trichotillomania and 43 controls using the NEO-Fave Factor Inventory, Hagh-Shenas and colleagues found that trichotillomania was associated with significantly higher scores on all neuroticism subscales and significantly lower scores on the compliance sub-scale of Agreeableness [5]. Finally, Keuthen and colleagues [6] examined personality factors in 164 adults with trichotillomania using the NEO-Five Factor Inventory and found that elevated openness, neuroticism, and less agreeableness were all associated with both greater pulling severity and that higher neuroticism was associated with less pulling control.

Reports on personality characteristics of trichotillomania and skin picking disorder have been few in number and have focused primarily on trichotillomania. The present study assessed personality traits in a large and well-characterized sample of adults with either trichotillomania or skin picking disorder or both. Based on the literature and our clinical experience, we hypothesized that people with trichotillomania or skin picking disorder would have high neuroticism scores and that higher scores would correlate with greater symptom severity.

The sample comprised 98 individuals, of whom 37 had TTM, 32 SPD, 10 had both, and 19 were controls. The mean age of the sample was 30.1 (8.4) years, 82 (84.5%) were female, and 75 (76.5%) were of White Caucasian ethnicity. The BFRB group and the control group did not differ significantly in terms of age (mean [SD] age in BFRB group: 29.5 [9.7] years; in controls: 26.2 [5.2]; F = 1.995, p = .161), nor gender distributions (N [%] female in the BFRB group: 78 [83.9%]; in controls: 15 [79.0%]; Fisher’s exact test p = 0.244). Groups did not differ in terms of racial-ethnic status (68 [78.2%] White-Caucasian in BFRBs; 11 [57.9%] in controls; Likelihood Ratio chi-square = 5.991, p = 0.200 using all racial-ethnic data/groupings).

The total NEO scores for the pooled BFRB group and controls are shown in Table 1 (Fig. 1 shows the scores by sub-groups). As compared to controls, the BFRB group had significantly elevated neuroticism scores (F = 32.85, p < 0.001; Cohen’s D = 1.85), lower extraversion scores (i.e. elevated introversion) (F = 5.32, p = 0.023; D = 0.59), and lower conscientiousness scores (i.e. elevated lack of conscientiousness) (F = 7.64, p = 0.007; D = 0.71). No significant differences between trichotillomania and skin picking disorder cases were evident on these three measures (all ANOVA p > 0.10). The BFRB group did not differ on openness scores, nor agreeableness scores, versus controls (both p > 0.40).

Table 2 shows correlations between NEO neuroticism, extraversion, and conscientiousness scores and relevant clinical measures in people with BFRBs. Only findings that were significant at Bonferroni corrected threshold were considered further herein. It can be seen that neuroticism was significantly related to both hair pulling and skin picking severity (small-medium effect sizes) as well as elevated perceived stress (large effect size), worse anxiety and depressive symptoms (large effect sizes), and poorer quality of life (medium effect size). Introversion (i.e. lower extraversion) was significantly associated with worse picking severity, higher perceived stress (large effect size), and higher depression (medium effect sizes). Lack of conscientiousness was significantly associated with more depressive symptoms (medium effect size), higher perceived stress (medium effect size), and higher impulsivity (large effect size).

To our knowledge, this is one of the few studies to examine personality features in adults with either trichotillomania or skin picking disorder or both. We also included a control group to contextualize the findings in the patients. Our analyses indicate that increased neuroticism was significantly statistically related to both hair pulling and skin picking severity, as well as anxiety, depression, and perceived stress. Neuroticism conceptually relates to experiencing negative affect (including anxiety/depression), and self-doubting. This is in keeping with a previous study [6] in trichotillomania and extends those findings to skin picking disorder as well. Unlike previous studies [5, 6], however, neither openness nor agreeableness were significantly different in those with BFRBs compared to controls. Having shown the large effect size association with neuroticism, the question remain as to what exactly is the relationship between neuroticism and these disorders? Research meta-analysis has shown that neuroticism seems to be a trait associated with multiple psychiatric disorders (albeit stronger in some than others, see [27, 28]), with the effect size seen here on par with that reported in mood and anxiety disorders and higher than that reported in substance use disorders [29]. The lack of specificity of neuroticism to BFRBs suggest that perhaps this personality trait is a vulnerability marker to many disorders, to varying degrees, including BFRBs. Additionally, as with other disorders, the causal directionality of our findings merits future study. Does the tendency to experience negative affect lead to pulling and picking or does the BFRB behavior drive the neuroticism? Longitudinal studies are needed to better understand the temporal relationship, but this second confirmatory study highlights the potential for treatment targeting negative affect in both trichotillomania and skin picking disorder.

Another significant personality variable in BFRBs was introversion (i.e. relative lack of extraversion). Introversion measures reduced social engagement, and a tendency to focus on one’s own thoughts or feelings. Interestingly, our data indicate that introversion was significantly associated with higher skin picking severity, as well as with worse mood and higher levels of perceived stress. One interpretation of these data is that extraversion may have a sort of ameliorative or ‘protective’ effect on picking severity and may be linked to better mood and less stress in both disorders. A recent study in generalized anxiety disorder demonstrated that either cognitive behavior therapy or metacognitive therapy were both effective in increasing extraversion [30]. It may therefore be worthwhile to examine whether a similar therapy could increase extraversion and possibly improve symptoms simultaneously in people with BFRBs.

Lack of conscientiousness was significantly associated with more depressive symptoms, more impulsivity, and higher perceived stress in both trichotillomania and skin picking. Conscientiousness measures a tendency to be responsible and goal-directed. The link between lack of conscientiousness and heightened impulsivity is in keeping with prior conceptualizations linking the two concepts. Recent data demonstrate that there appears to be a subtype of both trichotillomania and skin picking disorder characterized by marked impulsivity [31]. This has been further confirmed by several studies finding deficiencies on objective cognitive measures of response inhibition as well [32]. Perhaps one means of improving impulsive responding, and thereby possibly improve BFRB symptoms, would be to increase conscientiousness. A recent study in adults with depression found that mindfulness-based cognitive therapy successfully improved conscientious, albeit with small effect size [33].

Several limitations should be considered in this study. Because of the relatively small sample sizes involved, our between-group comparisons focused on all BFRBs versus controls, rather than examining all subpopulations. For the same reason, the study did not undertake multiple comparison corrections for the between-group analysis, nor did it undertake multivariate modelling, both of which would have necessitated a considerably larger sample size. Future work using larger sample sizes is needed to further confirm and extend upon these findings, including exploring the role of comorbidities.

In conclusion, this is one of very few studies to have examined personality in the context of BFRBs. We identified a number of personality features associated with BFRBs: neuroticism with very large effect size, and introversion plus lack of conscientiousness with medium effect sizes. In turn, these personality features showed a number of associations with features of illness in those with BFRBs including perceived stress, mood/anxiety, disability/impairment, and impulsivity. Some of these associations were of large effect size. The findings have potential implications for how BFRBs are assessed, as well as in terms of potential enhancement of treatment options for these neglected but prevalent conditions.