Hair pulling disorder (HPD; trichotillomania) and skin picking disorder (SPD; excoriation disorder) are characterized by recurrent and distressing or impairing hair pulling and skin picking, respectively (American Psychiatric Association [APA], 2022). HPD and SPD have highly similar symptom presentations and share genetic underpinnings (Bienvenu et al., 2009; Monzani et al., 2014). There is an emerging consensus that HPD and SPD are closely related conditions, and the two disorders are often conceptualized as grooming disorders or body-focused repetitive behavior disorders (along with other body-focused habits such as excessive nail biting or nail picking). The aim of the study was to (1) examine the prevalence, co-occurrence, and clinical characteristics of HPD and SPD in an acute psychiatric sample and (2) explore to what extent HPD/SPD were associated with clinical and diagnostic variables in the sample.
At least four studies have examined the prevalence of HPD or SPD in general psychiatric populations using diagnostic interviews. Grant et al. (2005) interviewed 204 adult inpatients and found that 7 patients (3.4%) met criteria for current HPD. In another study (Tamam et al., 2008), 103 psychiatric inpatients were interviewed, and 3 (2.9%) met criteria for current HPD. Two studies examined the prevalence of both HPD and SPD. Grant et al. (2007) interviewed 102 adolescent inpatients and found that 4 (3.9%) met criteria for current HPD, and 12 (11.8%), for current SPD. Müller et al. (2011) examined a sample of 234 adult psychiatric inpatients and found that 2 patients (0.9%) met criteria for current HPD and 16 patients (6.8%) met criteria for current SPD.
None of the studies described above had large enough samples to examine the co-occurrence of HPD and SPD. However, research has shown relatively high rates of HPD in SPD samples, and vice versa. In a review of the literature (Snorrason et al., 2012) it was found that the rates of SPD in HPD samples ranged from 10% to 34% and the rates of HPD in SPD samples ranged from 5% to 30%. Likewise, Grant et al. (2021) recruited individuals with HPD or SPD from the community and found that 40 of 279 cases (14.3%) had both conditions. We are not aware of any study examining the co-occurrence of HPD and SPD in general psychiatric samples using diagnostic interviews.
Historically, theorists have often considered whether HPD/SPD has associations with nonsuicidal self-injury (NSSI), suicidality, or borderline personality disorder (BPD) (Favazza, 1998; Kimbrel et al., 2014; Mann et al., 2020; Mathew et al., 2020; McKay and Andover, 2012; Neziroglu and Mancebo, 2001). However, empirical examination of rates of these conditions in HPD or SPD samples is very scarce. More generally, HPD and SPD are often thought to be associated with emotional disorders, including depressive and anxiety disorders (APA, 2022). Several studies have documented high rates of comorbid anxiety and depressive disorders in some HPD or SPD samples, although results are quite variable across studies (Houghton et al., 2016; Keuthen et al., 2014). A notable limitation of the existing literature is a lack of comparison with general psychiatric samples.
In this study, we examined the prevalence and correlates of HPD and SPD among patients in an acute psychiatric sample. Semistructured interviews were administered to adult patients in a psychiatric partial hospital program. The first aim was to examine the prevalence, clinical characteristics, and co-occurrence of HPD and SPD in the sample. We expected the rates would be similar to those in inpatient samples (i.e., 1%–4% for HPD and 7%–12% for SPD), and we predicted that HPD and SPD would have significant co-occurrence and similarities in clinical characteristics (e.g., sex ratio and age at onset). The second aim was to examine to what extent clinical/diagnostic variables (e.g., NSSI and major depression) added to the prediction of HPD/SPD status in the sample. Given the paucity of empirical literature examining clinical correlates of HPD/SPD in psychiatric samples, we did not make specific predictions about associations between the clinical/diagnostic variables and HPD/SPD.
METHOD
Participants and Setting
Participants were adult patients presenting for treatment in a psychiatric partial hospital program at McLean Hospital in Belmont, MA. The sample included patients who were (1) admitted to the program between 10/17/2019 and 3/2/2022 and (2) completed diagnostic interviews for HPD or SPD. No patients were interviewed from 3/13/2020 to 7/30/2020 because of the COVID-19 pandemic. After 7/30/2020, treatment and assessments in the program were conducted via videoconferencing. Before this date, assessments had been conducted in person. (The two data sets were combined as there were no significant differences in the study variables between virtual and in-person assessments). There were 1065 admissions to the program during the study period (i.e., not including 3/13/2020 to 7/30/2020). A total of 150 patients had been admitted more than once (range, one to three times), and only data from the first admission (n = 55) were included. In addition, 424 patients did not complete the interview package because of clinical or logistic reasons (Snorrason et al., 2019).
The final sample included 599 individuals; thereof, 355 (59.3%) were female and 244 (40.7%) were male. Of the females, 97.7% identified as a woman, and 2.3%, as a nonbinary or transgender person. Of the males, 97.9% identified as a man, and 2.1%, as a nonbinary or transgender person. Most identified as Non-Hispanic/Latinx and White (82.5%). Other racial/ethnic categories endorsed in the sample were Hispanic/Latinx (5.4%), Asian/Asian American (4.0%), Black/African American (1.5%), Native American (0.2%), mixed race/ethnicity (4.7%), and not listed/don't know (2.8%). The average age was 34.4 years (SD, 13.8 years).
Interview Measures
Semistructured Diagnostic Interview for HPD and SPD
This interview was designed to assess past-month Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnoses of SPD and HPD (Snorrason and Lee, 2022). The interview consisted of separate diagnostic modules for HPD and SPD that were identical except one referred to hair pulling and the other to skin picking. Each module began with screening items documenting (1) lifetime history of habitual hair pulling/skin picking and (2) confirmation that the behavior occurred in the past month. (Picking at the fingers was included, but nail picking was excluded.) If participants endorsed both screening items, they were asked whether the behaviors, in the past month, resulted in (3) skin damage/hair loss, (4) repeated failed attempts at reducing or stopping the habit, (5) distress due to the behavior, and (6) impairment in functioning due to the behavior. The modules also determined if the hair pulling/skin picking was better accounted for by (1) NSSI, (2) body dysmorphic disorder (BDD), or (3) complications of another mental disorder (e.g., psychosis), medical/dermatological conditions, or the effects of substances. The instrument also assessed age at HPD/SPD onset; frequency of picking/pulling episodes per day/week/month; the average length of episodes in minutes; and primary, secondary, tertiary, and quaternary body locations of picking/pulling (i.e., up to four body locations rank-ordered by importance).
A diagnosis of past-month DSM-5 HPD or SPD was given if a participant endorsed (1) both screening questions, (2) skin damage/hair loss, (3) failed attempts at stopping the behaviors, (4) distress or impairment due to the behavior, and (5) no exclusion criteria. A diagnosis of past-month problematic skin picking/hair pulling was given if a participant endorsed (1) both screening items, (2) at least one diagnostic criteria (i.e., skin damage/hair loss, failed attempts at stopping the behavior, distress, or impairment), and (3) no exclusionary criteria. A diagnosis of past-month habitual hair pulling/skin picking was given if a participant endorsed (1) both screening items and (2) no exclusionary criteria.
Columbia Suicide Severity Rating Scale
The Columbia Suicide Severity Rating Scale (CSSRS; Posner et al., 2011) is a semistructured interview designed to assess suicidal ideation, suicidal behaviors, and NSSI in the past month. The CSSRS includes a 6-point ideation severity scale that was dichotomized to reflect the absence (score = 0) or presence (score = 1–5) of ideation in the past month. The suicide behavior scale documents four discrete suicidal behaviors (e.g., actual, aborted, or interrupted suicide attempts) and was dichotomized to reflect the absence (0) or presence (1) of suicidal behavior in the past month (i.e., at least one category endorsed). The CSSRS also includes an item documenting NSSI in the past month (absence = 0; presence = 1).
The BPD Module of the Structured Clinical Interview for DSM-5 Personality Disorders
The Structured Clinical Interview for DSM-5 Personality Disorders (First et al., 2016) is a semistructured interview designed to assess DSM-5 personality disorders. Only the BPD module was administered in the current study. The module assesses the nine DSM-5 criteria for BPD and gives a diagnosis of BPD if five of the nine criteria are present.
The Miniature International Neuropsychiatric Interview for DSM-5
The Miniature International Neuropsychiatric Interview (MINI) (Sheehan et al., 1998) is a semistructured screening interview for common DSM-5 diagnoses. The following diagnostic modules were administered and included in the study: major depressive episode (past 2 weeks), panic disorder (past month), agoraphobia (current), social anxiety disorder (past month), obsessive-compulsive disorder (past month), generalized anxiety disorder (past 6 months), alcohol use disorder (past year), substance use disorder (past year), binge eating disorder (past 3 months), and bulimia nervosa (past 3 months). In addition, modules assessing current mania, psychotic disorder, and psychotic mood disorders were administered but not included in the study owing to low endorsement rates in the sample (<2%).
Self-Report Measures
Patient Health Questionnaire
The Patient Health Questionnaire-9 (Kroenke et al., 2001) is a 9-item self-repot measure designed to assess symptoms of depression. We used a version of the scale that assesses symptoms in the past 24 hours. Responders rate each item on a 4-point scale. Possible scores range from 0 to 27, with higher scores indicating greater severity. This scale has been shown to have good psychometric properties among patients admitted to the partial hospital (Beard et al., 2016).
Generalized Anxiety Disorder Scale
The Generalized Anxiety Disorder Questionnaire (Spitzer et al., 2006) is a seven-item questionnaire designed to assess symptoms of generalized anxiety. We used a version of the scale that assesses symptoms in the past 24 hours. Items are rated on 4-point scale. Total scores can range from 0 to 21, with higher score indicating greater severity. Previous research has shown that this instrument has good psychometric properties among patients attending the partial hospital (Beard and Björgvinsson, 2014).
Distress Intolerance Index
The Distress Intolerance Index (DII) (McHugh and Otto, 2012) is a 10-item self-report measure of perceived inability to tolerate negative affective and aversive physiological states. Items are rated on a Likert scale ranging from 0 (very little) to 4 (very much). Total scores can range from 0 to 40, with higher scores indicating greater distress intolerance. The DII has been shown to have acceptable psychometric properties among patients in the partial hospital (McHugh et al., 2014).
Procedure
All instruments were administered during the second treatment day as part of routine clinical evaluation. The interviews were administered by clinical trainees/interns who received training and monthly supervision by licensed psychologists.
Data Analyses
Deidentified raw data are posted at https://osf.io/h9vga/. All analyses were conducted in IBM SPSS Statistics for Windows, version 26. We used chi-square and independent-sample t tests to examine group differences on categorical and continuous variables, respectively. We conducted chi-square tests and logistic regression analyses to examine the associations between HPD and SPD. In addition, we conducted a series of 14 logistic regressions to examine the association between combined HPD/SPD and 14 diagnostic/clinical variables. To account for multiple comparisons, alpha level was set at p < 0.003 (i.e., 0.05/15).
RESULTS
Aim 1: Prevalence, Clinical Characteristics, and Co-occurrence of HPD and SPD
Prevalence
Table 1 shows the prevalence of (1) habitual skin picking/hair pulling, (2) problematic skin picking/hair pulling, and (3) full diagnosis of DSM-5 SPD/HPD.
TABLE 1 -
Prevalence of Habitual, Problematic, and Disordered Skin Picking and Hair Pulling Among Patients in a Psychiatric Partial Hospital
|
Total Sample
(N = 599) |
Females
(n = 355) |
Males
(n = 244) |
|
|
|
n (%) |
95% CI, % |
n (%) |
95% CI, % |
n (%) |
95% CI, % |
χ2
|
p
|
| Skin picking |
|
|
|
|
|
|
|
|
| Habitual |
121 (20.2) |
17.1–23.6 |
76 (21.4) |
17.3–26.0 |
45 (18.4) |
13.8–23.9 |
0.8 |
0.374 |
| Problematic |
103 (17.2) |
14.3–20.5 |
66 (18.6) |
14.7–23.0 |
37 (15.2) |
10.9–20.3 |
1.2 |
0.275 |
| SPD |
54 (9.0) |
6.8–11.6 |
40 (11.3) |
8.2–15.0 |
14 (5.7) |
3.2–9.4 |
5.4 |
0.020 |
| Hair pulling |
|
|
|
|
|
|
|
|
| Habitual |
42 (7.0) |
5.1–9.4 |
31 (8.7) |
6.0–12.2 |
11 (4.5) |
2.3–7.9 |
4.0 |
0.047 |
| Problematic |
34 (5.7) |
4.0–7.8 |
25 (7.0) |
4.6–10.2 |
9 (3.7) |
1.7–6.9 |
3.0 |
0.081 |
| HPD |
14 (2.3) |
1.3–3.9 |
12 (3.4) |
1.8–5.8 |
2 (0.8) |
0.1–2.9 |
4.2 |
0.042 |
| Hair pulling and skin picking |
|
|
|
|
|
|
|
|
| Habitual |
141 (23.5) |
20.3–27.1 |
89 (25.1) |
20.8–29.8 |
52 (21.3) |
16.6–26.9 |
1.1 |
0.287 |
| Problematic |
123 (20.5) |
17.5–24-0 |
79 (22.3) |
18.2–26.9 |
44 (18.0) |
13.7–23.3 |
1.6 |
0.209 |
| HPD/SPD |
63 (10.5) |
8.3–13.2 |
48 (13.5) |
10.4–17.5 |
15 (6.1) |
3.8–9.9 |
8.4 |
0.004 |
Clinical Characteristics
In the SPD group (n = 54), the most commonly reported primary picking sites were face (n = 15), fingers (n = 14), head/scalp (n = 6), and upper arms/shoulders (n = 5). The average age at SPD onset was 14.4 years (SD, 7.4 years; range, 2–34 years), and the average lifetime duration of the SPD was 15 years (SD, 11.6 years; range, 0–54 years). In the HPD group (n = 14), the most common primary pulling site was scalp (n = 8), eyebrows (n = 4), eyelashes (n = 2), legs (n = 1), and beard (n = 1). The average age at onset was 16.2 years (SD, 7.2 years; range, 3–31 years), and the average lifetime duration of the HPD was 16.8 years (SD, 10.5 years; range, 5–39 years).
Co-occurrence
Patients who met criteria for HPD were more likely than other patients to meet criteria for SPD (35.7% vs. 8.4%; χ2 = 12.46, p < 0.0001), and patients who met criteria for SPD were more likely than other patients to meet criteria for HPD (9.3% vs. 1.7%; χ2 = 12.46, p < 0.0001). Expressed as odds ratios (ORs), patients who met criteria for SPD were 6 times more likely than other patients to meet criteria for HPD, and vice versa (OR, 6.01; 95% confidence interval [CI], 1.96–18.84; p = 0.002). Moreover, when age, sex, and other diagnostic variables were controlled for (see Table S1 and Table S2 in Supplemental Material, Supplemental Digital Content 1, https://links.lww.com/JNMD/A152), those with SPD were 7.6 times more likely than other patients to meet criteria for HPD (OR, 7.62; 95% CI, 2.08–27.95; p = 0.002), and those with HPD were 8.7 times more likely than other patients to meet criteria for SPD (OR, 8.70; 95% CI, 2.38–31.77; p = 0.001). None of the other diagnoses assessed in the study had a unique association with HPD or SPD (see Supplemental Material, Supplemental Digital Content 1, https://links.lww.com/JNMD/A152).
Aim 2: Correlates of HPD and SPD
Demographics and Self-Report Measures
Table 2 shows the comparison between the combined HPD/SPD sample and other patients on demographic variables and the self-report questionnaires. The patients with HPD/SPD were significantly younger and more likely to be female compared with other patients. The groups did not differ with respect to race, ethnicity, or self-reported depression, generalized anxiety, or distress intolerance.
TABLE 2 -
Demographic and Clinical Comparison Between Patients With and Without HPD/SPD in a Psychiatric Partial Hospital Program
|
HPD/SPD
(n = 63) |
No HPD/SPD
(n = 536) |
t/χ2
|
p
|
| Demographics |
|
|
|
|
| Age, mean (SD), y |
30.3 (9.8) |
34.9 (14.2) |
2.5 |
0.001 |
| Female sex, n (%) |
48 (76.2) |
307 (57.3) |
8.4 |
0.004 |
| Non-Hispanic White, n (%) |
54 (85.7) |
440 (82.1) |
0.5 |
0.474 |
| Self-report scales |
|
|
|
|
| Depression (PHQ-9) |
10.1 (5.4) |
9.7 (5.8) |
0.5 |
0.639 |
| Generalized Anxiety (GAD-7) |
8.3 (5.1) |
7.9 (5.2) |
0.5 |
0.586 |
| DII |
1.4 (1.2) |
1.4 (1.3) |
0.3 |
0.822 |
DII indicates Distress Intolerance Index; GAD-7, Generalized Anxiety Disorder Questionnaire, 7-item version; PHQ-9, Patient Health Questionnaire, 9-item version.
Clinical and Diagnostic Variables
Table 3 shows a summary of results from a series of logistic regressions in which clinical and diagnostic variables were used to predict HPD/SPD status, after adjusting for age and sex. Diagnosis of generalized anxiety disorder was associated with HPD/SPD. None of the other clinical or diagnostic variables were significantly associated with HPD/SPD.
TABLE 3 -
Summary of Results From Logistic Regression Predicting Past-Month Diagnosis of HPD or SPD (Absence = 0, Presence =1) Adjusting for Age and Sex
|
n (%) |
OR (95% CI) |
p
|
| SCID-5-PD BPD module |
|
|
|
| BPD |
118 (19.9) |
1.57 (0.86–2.85) |
0.139 |
| CSSRS (past month) |
|
|
|
| Suicidal ideation |
348 (58.2) |
0.76 (0.44–1.30) |
0.313 |
| Suicidal behavior |
49 (8.2) |
0.83 (0.28–2.42) |
0.732 |
| NSSI |
72 (12.1) |
1.42 (0.69–2.92) |
0.343 |
| MINI diagnoses (current) |
|
|
|
| Major depressive episode |
348 (58.3) |
1.20 (0.69–2.01) |
0.515 |
| Panic disorder |
89 (15.0) |
1.10 (0.54–2.23) |
0.791 |
| Agoraphobia |
51 (8.6) |
1.48 (0.65–3.35) |
0.353 |
| Social anxiety disorder |
143 (24.1) |
2.07 (1.18–3.63) |
0.012 |
| Obsessive-compulsive disorder |
101 (17.1) |
1.28 (0.68–2.44) |
0.446 |
| Generalized anxiety disorder |
317 (53.6) |
2.45 (1.35–4.50) |
0.003 |
| Alcohol use disorder |
128 (21.5) |
0.83 (0.42–1.63) |
0.590 |
| Substance use disorder |
141 (24.0 |
1.00 (0.52–1.93) |
0.991 |
| Bulimia nervosa |
15 (2.5) |
2.79 (0.84–9.25) |
0.093 |
| Binge eating disorder |
19 (3.2) |
0.33 (0.04–2.59) |
0.295 |
SCID-5-PD BPD module indicates the BPD module of the Structured Clinical Interview for DSM-5 Personality Disorders.
DISCUSSION
The aim of this study was to examine the prevalence and clinical correlates of HPD and SPD among adult patients in a psychiatric partial hospital. The results showed that pathological skin picking was quite common in this setting, with 17.2% of patients experiencing at least some problems due to skin picking and 9% meeting full DSM-5 criteria for SPD. The prevalence of problematic hair pulling and HPD was 5.7% and 2.3%, respectively. Overall, these results parallel those from studies in inpatient psychiatric samples (Grant et al., 2005, 2007; Müller et al., 2011; Tamam et al., 2008). Given the relatively high prevalence rates, it may be advisable to screen for these disorders in psychiatric settings.
Consistent with previous literature (Snorrason et al., 2012), the results showed that HPD and SPD had overall similar clinical characteristics. The results also showed strong co-occurrence between HPD and SPD. After controlling for sex, age, and other diagnoses, patients with SPD were 7.6 times more likely than other patients to meet criteria for HPD, and patients with HPD were 8.7 times more likely than other patients to meet criteria for SPD. These results are generally consistent with the notion that HPD and SPD are closely related conditions that may share important underpinnings (Monzani et al., 2014).
The results showed that HPD/SPD had limited associations with internalizing psychopathology in this sample. There was no association between HPD/SPD and suicidality or NSSI. This is consistent with evidence showing that HPD/SPD and NSSI have quite different symptom presentations (Mathew et al., 2020). In addition, the results showed that HPD/SPD did not have significant associations with emotional disorders in the sample, including major depression, panic disorder, social anxiety disorder, obsessive-compulsive disorder, and BPD. A notable exception was a significant association between HPD/SPD and a diagnosis of generalized anxiety disorder assessed with the MINI. However, these findings should be interpreted cautiously given that the HPD/SPD group did not differ from other patients on self-report measures of generalized anxiety, depression, or distress intolerance.
Overall, our results are in line with previous research showing relatively weak association between HPD/SPD and internalizing conditions. For example, in an early study, Christenson et al. (1992) compared female patients with HPD with a sample of age-matched female psychiatric outpatients and found that the patients with HPD had lower rates of BPD assessed with a diagnostic interview and lower self-reported depression and psychological maladjustment. Similarly, evidence suggests that neuroticism is more strongly associated with symptoms of OCD, hoarding disorder, and BDD than with symptoms of HPD and SPD (Keuthen et al., 2015; Watson et al., 2018). Finally, factor analytic studies have consistently shown that self-reported HPD and SPD symptoms load on a shared underlying “grooming” factor in both clinical and nonclinical samples (Hartmann et al., 2020; Maraz et al., 2017), and this grooming factor has been shown to have relatively limited association with negative emotionality (Snorrason et al., 2021, 2022).
The current study has important limitations that should be considered when interpreting the results. First, replication in larger samples is warranted. Our study might not have had sufficient power to detect association with diagnoses that had low prevalence in the sample (e.g., eating disorders). Similarly, relatively few patients in the sample had HPD, and we therefore had to examine correlates of a combined HPD/SPD group rather than correlates of each diagnosis separately. There is compelling rationale for grouping HPD and SPD together; however, future studies, using larger samples, should replicate the current analyses in separate HPD and SPD samples. In addition, the study assessed only HPD and SPD, and future researchers may want to include a broader range of BFRBs such as excessive nail biting and nail picking.
Second, although investigating comorbidity patterns in clinical populations is informative, samples drawn from clinical settings may not accurately reflect the target population. It is therefore important that future researchers replicate the study in unselected samples that are more representative of the general population. Fourth, the study should be replicated in more ethnically and socioeconomically diverse samples.
In conclusion, SPD and HPD are relatively common and frequently co-occurring disorders that appear to have limited associations with internalizing psychopathology, at least in psychiatric settings.
DISCLOSURES
Statement of ethical considerations: The study was approved as an exempt protocol (using an existing deidentified dataset) by the McLean Hospital/Partners Institutional Review Board.
Author contributions: All authors contributed to writing the original manuscript and critically reviewed the final version of the manuscript. Conceptualization: I. S. and N. J. K. Data curation: C. B. and T. B. Formal analysis: I. S. All authors have read and approved the submitted manuscript.
The authors declare no conflict of interest.
REFERENCES
American Psychiatric Association (2022)
Diagnostic and statistical manual of mental disorders, fifth edition, text revision (DSM-5-TR). Washington, DC: American Psychiatric Association.
Beard C, Björgvinsson T (2014) Beyond generalized anxiety disorder: Psychometric properties of the GAD-7 in a heterogeneous psychiatric sample.
J Anxiety Disord. 28:547–552.
Beard C, Hsu KJ, Rifkin LS, Busch AB, Björgvinsson T (2016) Validation of the PHQ-9 in a psychiatric sample.
J Affect Disord. 193:267–273.
Bienvenu OJ, Wang Y, Shugart YY, Welch JM, Grados MA, Fyer AJ, Rauch SL, McCracken JT, Rasmussen SA, Murphy DL, Cullen B, Valle D, Hoehn-Saric R, Greenberg BD, Pinto A, Knowles JA, Piacentini J, Pauls DL, Liang KY, Willour VL, Riddle M, Samuels JF, Feng G, Nestadt G (2009) Sapap3 and pathological grooming in humans: Results from the OCD collaborative genetics study.
Am J Med Genet B Neuropsychiatr Genet. 150:710–720.
Christenson GA, Chernoff-Clementz E, Clementz BA (1992) Personality and clinical characteristics in patients with trichotillomania.
J Clin Psychiatry. 53:407–413.
Favazza AR (1998) The coming of age of self-mutilation.
J Nerv Ment Dis. 186:259–268.
First MB, Williams JBW, Benjamin L (2016)
Structured clinical interview for DSM-5 personality disorders (SCID-5-PD). Washington. DC: American Psychiatric Publishing.
Grant JE, Levine L, Kim D, Potenza MN (2005) Impulse control in adult psychiatric inpatients.
Am J Psychiatry. 162:2184–2188.
Grant JE, Peris TS, Ricketts EJ, Lochner C, Stein DJ, Stochl J, Chamberlain SR, Scharf JM, Dougherty DD, Woods DW, Piacentini J, Keuthen NJ (2021) Identifying subtypes of trichotillomania (hair pulling disorder) and excoriation (skin picking) disorder using mixture modeling in a multicenter sample.
J Psychiatr Res. 137:603–612.
Grant JE, Williams KA, Potenza MN (2007) Impulse-control disorders in adolescent psychiatric inpatients: Co-occurring disorders and sex differences.
J Clin Psychiatry. 68:1584–1592.
Hartmann AS, Staufenbiel T, Bielefeld L, Buhlmann U, Heinrichs N, Martin A, Ritter V, Kollei I, Grocholewski A (2020) An empirically derived recommendation for the classification of body dysmorphic disorder: Findings from structural equation modeling.
PloS One. 15:e0233153.
Houghton DC, Maas J, Twohig MP, Saunders SM, Compton SN, Neal-Barnett AM, Franklin ME, Woods DW (2016) Comorbidity and quality of life in adults with hair pulling disorder.
Psychiatry Res. 239:12–19.
Keuthen NJ, Altenburger EM, Pauls D (2014) A family study of trichotillomania and chronic hair pulling.
Am J Med Genet B Neuropsychiatr Genet. 165:167–174.
Keuthen NJ, Tung ES, Altenburger EM, Blais MA, Pauls DL, Flessner CA (2015) Trichotillomania and personality traits from the five-factor model.
Braz J Psychiatry. 37:317–324.
Kimbrel NA, Johnson ME, Clancy C, Hertzberg M, Collie C, Van Voorhees EE, Dennis MF, Calhoun PS, Beckham JC (2014) Deliberate self-harm and suicidal ideation among male Iraq/Afghanistan-era veterans seeking treatment for PTSD.
J Trauma Stress. 27:474–477.
Kroenke K, Spitzer RL, Williams JB (2001) The PHQ-9: Validity of a brief depression severity measure.
J Gen Intern Med. 16:606–613.
Mann AJ, Van Voorhees EE, Patel TA, Wilson SM, Gratz KL, Calhoun PS, Beckham JC, Kimbrel NA (2020) Nail-biting, scab-picking, and tattooing as nonsuicidal self-injury (NSSI): A deviant case series analysis of the proposed NSSI disorder diagnostic criteria.
J Clin Psychol. 76:2296–2313.
Maraz A, Hende B, Urbán R, Demetrovics Z (2017) Pathological grooming: Evidence for a single factor behind trichotillomania, skin picking and nail biting.
PLoS One. 12:e0183806.
Mathew AS, Davine TP, Snorrason I, Houghton D, Woods DW, Lee H-J (2020) Body-focused repetitive behaviors and non-suicidal self-injury: A comparison of clinical characteristics and symptom features.
J Psychiatr Res. 124:115–122.
McHugh RK, Kertz SJ, Weiss RB, Baskin-Sommers AR, Hearon BA, Björgvinsson T (2014) Changes in distress intolerance and treatment outcome in a partial hospital setting.
Behav Ther. 45:232–240.
McHugh RK, Otto MW (2012) Refining the measurement of distress intolerance.
Behav Ther. 43:641–651.
McKay D, Andover M (2012) Should nonsuicidal self-injury be a putative obsessive-compulsive-related condition? A critical appraisal.
Behav Modif. 36:3–17.
Monzani B, Rijsdijk F, Harris J, Mataix-Cols D (2014) The structure of genetic and environmental risk factors for dimensional representation of
DSM-5 obsessive-compulsive spectrum disorders.
JAMA Psychiat. 71:182–189.
Müller A, Rein K, Kollei I, Jacobi A, Rotter A, Schütz P, Hillemacher T, de Zwaan M (2011) Impulse control disorders in psychiatric inpatients.
Psychiatry Res. 188:434–438.
Neziroglu F, Mancebo M (2001) Skin picking as a form of self-injurious behavior.
Psychiatric Ann. 31:549–555.
Posner K, Brown GK, Stanley B, Brent DA, Yershova KV, Oquendo MA, Currier GW, Melvin GA, Greenhill L, Shen S, Mann JJ (2011) The Columbia–Suicide Severity Rating Scale: Initial validity and internal consistency findings from three multisite studies with adolescents and adults.
Am J Psychiatry. 168:1266–1277.
Sheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E, Hergueta T, Baker R, Dunbar GC (1998) The Mini-International Neuropsychiatric Interview (MINI): The development and validation of a structured diagnostic psychiatric interview for
DSM-IV and ICD-10.
J Clin Psychiatry. 59:22–33.
Snorrason I, Beard C, Christensen K, Bjornsson A, Björgvinsson T (2019) Body dysmorphic disorder and major depressive episode have comorbidity-independent associations with suicidality in an acute psychiatric setting.
J Affect Disord. 259:266–270.
Snorrason I, Beard C, Peckham AD, Björgvinsson T (2021) Transdiagnostic dimensions in obsessive-compulsive and related disorders: Associations with internalizing and externalizing symptoms.
Psychol Med. 51:1657–1665.
Snorrason I, Belleau EL, Woods DW (2012) How related are hair pulling disorder (trichotillomania) and skin picking disorder? A review of evidence for comorbidity, similarities and shared etiology.
Clin Psychol Rev. 32:618–629.
Snorrason I, Conway CC, Falkenstein MJ, Kelley KN, Kuckertz JM (2022) Higher order compulsivity versus grooming dimensions as treatment targets for the
DSM-5 obsessive-compulsive and related disorders.
Depress Anxiety. 39:49–55.
Snorrason I, Lee H-J (2022) Assessing excoriation (skin-picking) disorder: Clinical recommendations and preliminary examination of a comprehensive interview.
Int J Environ Res Public Health. 19:6717.
Spitzer RL, Kroenke K, Williams JB, Löwe B (2006) A brief measure for assessing generalized anxiety disorder: The GAD-7.
Arch Intern Med. 166:1092–1097.
Tamam L, Zengin M, Karakus G, Ozturk Z (2008) Impulse control disorders in an inpatient psychiatry unit of a university hospital.
Klinik Psikofarmakoloji Bülteni/Bull Clin Psychopharmacol. 18:153–161.
Watson D, Stasik-O'Brien SM, Ellickson-Larew S, Stanton K (2018) Explicating the dispositional basis of the OCRDs: A hierarchical perspective.
J Psychopathol Behav Assess. 40:497–513.
