Abstract
Introduction
Trichotillomania (TTM) is a body-focused repetitive disorder linked to psychiatric comorbidities. Comprehensive studies mapping its associations with a range of conditions remain limited. This study examines TTMs associations with psychiatric, neurodevelopmental, substance-related, reproductive, and social factors using a national database.
Methods
We performed a case-control study using the All of Us Research Program database. TTM cases (n = 40) were matched to controls (n = 400) based on age, sex, and ethnicity. Multivariate logistic regression was used to examine associations with comorbidities and lifestyle factors, controlling for demographic variables.
Results
TTM was significantly associated with obsessive-compulsive disorder (odds ratio [OR] 18.3), borderline personality disorder (OR 15), anxiety disorders (OR 10.2), alcohol abuse (OR 6.13), depression (OR 5.89), and vitamin D deficiency (OR 4.2) (all p < 0.01). Other significant associations included fatigue, social anxiety, post-traumatic stress disorder, ADHD, and difficulty running errands alone.
Conclusion
Our findings highlight the strong association between TTM and a wide range of psychiatric and behavioral conditions, emphasizing the need for integrated treatment strategies addressing both psychiatric and physical aspects.
Keywords: Trichotillomania, Body-focused repetitive disorders, Alopecia, Psychodermatology
Introduction
Trichotillomania (TTM) is characterized by the recurrent urge to pull out one’s own hair from any region of the body, often leading to mechanical alopecia [1]. TTM is understood to be influenced by other psychiatric conditions [2], and first-line therapy for the condition has generally been habit reversal therapy (HRT [2]. However, while previous work has explored the link between TTM and certain psychiatric comorbidities, there remains a lack of comprehensive research mapping the full range of associated conditions which may co-occur with TTM. We analyzed cases of TTM for associations with psychiatric comorbidities, neurodevelopmental and cognitive disorders, substance-related disorders, reproductive disorders, and social and situational factors using a national database to analyze patterns of comorbidity and risk factors. By leveraging this large-scale data, we aimed to provide a more nuanced understanding of the broader associations with TTM, offering insights into how these factors may contribute to the disorder’s development and course.
Methods
We performed a case-control study including patients in the US recruited to the All of Us (AoU) Research Program, a national initiative led by the National Institutes of Health to build a database of health data from voluntary adult participants. Systematized Nomenclature of Medicine (SNOMED) diagnostic codes from electronic health record data were used to identify cases of TTM (SNOMED 17155009), and also various comorbidities, including obsessive-compulsive disorder (OCD), depression, attention-deficit/hyperactivity disorder, post-traumatic stress disorder (PTSD), body dysmorphic disorder, anorexia, bulimia, insomnia, dyssomnia, psychoactive substance use, alcohol abuse, obesity, drug abuse, schizophrenia, repetitive self-excoriation and excoriation of skin, migraine, Vitamin D deficiency, hypercalcemia, seborrheic dermatitis, autism spectrum disorder, Huntington’s chorea, fibromyalgia, presence of foreign body in stomach, borderline personality disorder (BPD), hoarding disorder, dissociative disorder, multiple personality disorder, victim of sexual abuse, restless legs syndrome, premenstrual tension syndrome, premenstrual dysphoric disorder, polycystic ovary syndrome, acute stress disorder, stress, social anxiety disorder, separation anxiety disorder, alcohol-induced anxiety disorder, anxiety disorder, fatigue, mental disorders during pregnancy, and hallucinogen-induced organic mental disorder. AoU concept IDs were used to identify lifestyle risk factors of difficulty running errands alone, difficulty concentrating, smoking status (100+ cigarettes in a lifetime), health insurance status, and stable housing concern in the previous 6 months. Each case of TTM was matched to ten controls based on age, sex, and ethnicity using nearest neighbor propensity score matching. Multivariate logistic regression was used to calculate odds ratios and p value. In each regression analysis, age, sex, and race were included as covariates. Statistical significance was set at p < 0.05. The Benjamini-Hochberg procedure was applied to adjust for multiple hypothesis testing. Conditions corresponding to a false discovery rate (FDR) (q value) of less than 0.1 were considered significant.
Results
Our analysis included 40 cases of adult patients with TTM and 400 controls matched on age, sex, and self-reported race. Patients with TTM were 48.2 years old on average, 80% female, and majority White (65.5%) (Table 1). Matched controls were similar for all baseline demographic features. Adults with TTM were more likely to have OCD (odds ratio [OR] 18.3; 95% CI: 4.6–72.9), BPD (OR 15; 95% CI: 4.27–52.7), anxiety disorder (OR 10.2; 95% CI: 4.51–23.1), alcohol abuse (OR 6.13; 95% CI: 2.47–15.2), depression (OR 5.89; 95% CI: 2.94–11.8), and vitamin D deficiency (OR 4.2; 95% CI: 2.06–8.56) (all p < 0.01) (Table 2). Our analysis also revealed several conditions with statistically significant associations with TTM (p < 0.05) but with q values >0.1: repetitive self-excoriation (OR 24.1; 95% CI: 2.03–287), social anxiety (OR 16.7; 95% CI: 2.69–103), stress (OR 17; 95% CI: 2.66–109), ADHD (OR 5.34; 95% CI: 1.68–17), fatigue (OR 3.18; 95% CI: 1.52–6.66), PTSD (OR 3.11; 95% CI: 1.22–7.93), and difficulty running errands alone (OR 2.71; 95% CI: 1.08–6.79). Patients with TTM and controls were similar in terms of lifestyle risk factors relating to housing stability, insurance status, and smoking history (all p > 0.05).
Table 1.
Demographic characteristics of adults with TTM and controls matched on age, sex, and self-reported race
| TTM (n = 40) | Matched controls (n = 400) | p value | |
|---|---|---|---|
| Age, mean (SD), years | 48.2 (17.3) | 47.2 (16.1) | 0.7498 |
| Sex at birth count, n (%) | 0.4063 | ||
| Male | ≤20a | 59 (15) | |
| Female | 32 (80) | 332 (83) | |
| Other | ≤20a | ≤20a | |
| Self-reported race/ethnicity count, n (%) | 0.998 | ||
| White | 26 (65.5) | 247 (61.8) | |
| Black | ≤20a | 71 (17.8) | |
| Other | ≤20a | 82 (20.5) |
aCount and percent hidden as per All of Us data policy: https://www.researchallofus.org/wp-content/themes/research-hub-wordpress-theme/media/2020/05/AoU_Policy_Data_and_Statistics_Dissemination_508.pdf.
Table 2.
Association of TTM with comorbidities and lifestyle risk factors for disease
| Comorbidity or lifestyle factor | TTM patients (n = 40), n (%) | Controls (n = 400), n (%) | Odds ratio and 95% confidence interval | p value | q value |
|---|---|---|---|---|---|
| Anxiety disorder | 31 (78) | 116 (29) | 10.2 [4.51–23.1] | <0.001 | 0.000011295 |
| Depression | 21 (52) | 66 (16) | 5.89 [2.94–11.8] | <0.001 | 0.00013815 |
| Borderline personality disorder | ≤20a | ≤20a | 15 [4.27–52.7] | <0.001 | 0.003645 |
| Obsessive-compulsive disorder | ≤20a | ≤20a | 18.3 [4.6–72.9] | <0.001 | 0.004185 |
| Vitamin D deficiency | ≤20a | 71 (18) | 4.2 [2.06–8.56] | <0.001 | 0.006813 |
| Alcohol abuse | ≤20a | ≤20a | 6.13 [2.47–15.2] | <0.001 | 0.0071025 |
| Fatigue | ≤20a | 61 (15) | 3.18 [1.52–6.66] | 0.00213 | 0.1251 |
| Social anxiety | ≤20a | ≤20a | 16.7 [2.69–103] | 0.0025 | 0.1251 |
| Stress | ≤20a | ≤20a | 17 [2.66–109] | 0.00278 | 0.1251 |
| Attention-deficit/hyperactivity disorder | ≤20a | ≤20a | 5.34 [1.68–17] | 0.00443 | 0.181227273 |
| Repetitive self-excoriation | ≤20a | ≤20a | 24.1 [2.03–287] | 0.0117 | 0.278372093 |
| Post-traumatic stress disorder | ≤20a | 29 (7.2) | 3.11 [1.22–7.93] | 0.0175 | 0.278372093 |
| Difficulty running errands alone | ≤20a | 31 (7.8) | 2.71 [1.08–6.79] | 0.0334 | 0.2875 |
| Autism spectrum disorder | ≤20a | ≤20a | 12.9 [0.693–240] | 0.0865 | 0.632177 |
| Premenstrual tension syndrome | ≤20a | ≤20a | 4.37 [0.808–23.6] | 0.0867 | 0.632177 |
| Premenstrual dysphoric disorder | ≤20a | ≤20a | 11.9 [0.697–204] | 0.0871 | 0.632177 |
| Bulimia | ≤20a | ≤20a | 12.1 [0.674–217] | 0.0906 | 0.647143 |
| Excoriation of skin finding | ≤20a | ≤20a | 10.9 [0.646–184] | 0.0976 | 0.684 |
| Dissociative | ≤20a | ≤20a | 10.7 [0.641–179] | 0.0988 | 0.684 |
| Difficulty concentrating | ≤20a | 56 (14) | 1.88 [0.838–4.2] | 0.126 | 0.846269 |
| Restless legs syndrome | ≤20a | ≤20a | 2.55 [0.768–8.5] | 0.126 | 0.846269 |
| Fibromyalgia | ≤20a | ≤20a | 2.79 [0.738–10.6] | 0.131 | 0.86087 |
| PCOS | ≤20a | ≤20a | 2.84 [0.73–11] | 0.132 | 0.86087 |
| Migraine | ≤20a | 57 (14) | 1.84 [0.81–4.19] | 0.145 | 0.932143 |
| Obesity | ≤20a | 112 (28) | 1.58 [0.791–3.14] | 0.196 | 1 |
| Seborrheic dermatitis | ≤20a | ≤20a | 2.03 [0.623–6.61] | 0.24 | 1 |
| Dyssomnia | ≤20a | ≤20a | 3.42 [0.339–34.5] | 0.297 | 1 |
| Schizophrenia | ≤20a | ≤20a | 3.39 [0.33–34.8] | 0.305 | 1 |
| Insomnia | ≤20a | 49 (12) | 1.53 [0.629–3.74] | 0.346 | 1 |
| Acute stress disorder | ≤20a | 17 (4.2) | 1.81 [0.497–6.59] | 0.368 | 1 |
| Stable housing concern | ≤20a | 68 (17) | 0.715 [0.269–1.9] | 0.502 | 1 |
| Smoking | ≤20a | 127 (32) | 0.777 [0.367–1.65] | 0.509 | 1 |
| Pregnancy-related mental health disorders | ≤20a | ≤20a | 0.555 [0.0702–4.39] | 0.577 | 1 |
| Drug abuse | ≤20a | ≤20a | 1.25 [0.15–10.4] | 0.836 | 1 |
| Has insurance | 39 (98) | 388 (97) | 1.17 [0.146–9.39] | 0.882 | 1 |
| Psychoactive substance use | ≤20a | ≤20a | 1.11 [0.136–9.1] | 0.921 | 1 |
PCOS, polycystic ovary syndrome.
aCount and percent hidden as per All of Us data policy: https://www.researchallofus.org/wp-content/themes/research-hub-wordpress-theme/media/2020/05/AoU_Policy_Data_and_Statistics_Dissemination_508.pdf.
Discussion
We showed that adults with TTM are more likely to have comorbid psychiatric, behavioral, and functional impairment conditions compared to matched controls. The correlation between TTM and conditions such as anxiety, depression, OCD, ADHD, and stress have been well-documented [3–6], with TTM patients often having higher levels of anxiety disorders and obsessive thoughts, which can trigger or worsen hair-pulling. These intrusive thoughts may resemble OCD obsessions, with hair-pulling acting as a compulsive response to reduce anxiety.
Previous research has linked hair-pulling to personality disorders in African American women [7]. Our study, focusing on a predominantly White female TTM sample, found a higher prevalence of BPD, which is characterized by emotional instability and impulse control issues. This suggests that impulsivity, emotion dysregulation, and self-destructive behaviors may overlap with compulsive hair-pulling across demographics. Addressing emotional dysregulation in BPD may help reduce TTM symptoms.
Furthermore, a 2023 study found that 16/121 adults with TTM indicated hazardous alcohol use, though this difference was not statistically significant when compared to the control sample [8], and a 2019 study found relationships between lifetime alcohol dependence and TTM [9]. In contrast, our study found a significant association between alcohol abuse and TTM, suggesting shared psychological or behavioral mechanisms. Physicians should screen for alcohol use disorders in TTM patients and vice versa, as untreated alcohol abuse can hinder TTM treatment and worsen compulsive behaviors. Both conditions often co-occur with mood disorders, emphasizing the need comprehensive evaluation.
We also discovered a notable association between Vitamin D deficiency and TTM. The literature reports a few documented cases of TTM triggered by Vitamin D deficiency [10, 11], where low vitamin D3 levels were the sole abnormal finding in patients. Remarkably, supplementation resulted in a significant reduction in hair-pulling behavior, suggesting a potential link between Vitamin D levels and TTM [10, 11]. Our study provides the first epidemiological evidence highlighting the role of Vitamin D deficiency in TTM patients. While more research is necessary to confirm this connection, Vitamin D might influence the development and severity of TTM through multiple pathways. Of Vitamin D has an important role in brain development and function, as evidenced by the presence of Vitamin D receptors and the enzyme 1α-hydroxylase in the human brain [9]. In children, Vitamin D deficiency during critical developmental periods has been associated with several psychiatric conditions due to its regulatory effects on neurotransmitters like dopamine [12]. Moreover, Vitamin D deficiency has been independently linked to depression [13], anxiety [13], and stress [13] – all of which are commonly associated with TTM.
Since Vitamin D is synthesized through sunlight exposure [14], limited outdoor activities or living in areas with minimal sunlight can contribute to both Vitamin D deficiency and may thus lead to increased emotional or mental distress. Such distress may, in turn, exacerbate the onset and severity of TTM symptoms. Future research could explore the potential benefits of addressing Vitamin D deficiency in TTM patients through supplementation or lifestyle modifications. These interventions may complement existing treatments, helping alleviate distress and reduce compulsive hair-pulling behaviors.
We also found that self-excoriation (skin picking) had a higher likelihood in TTM patients. A 2016 study found that individuals with co-occurring TTM and skin picking disorder may have more problematic symptoms with the primary repetitive behavior [15]. Further research is needed into understanding if the presence of one body-focused repetitive disorder such as TTM predisposes patients into developing another; however, in patients presenting with TTM, other body-focused repetitive disorders that affect skin, nails, and body hair must be examined for.
Additionally, a 2024 survey study found that 19.1% (40 individuals) of those with TTM reported symptoms consistent with current PTSD, with participants more likely to be male and have a co-occurring alcohol use disorder [16]. Our findings show a higher likelihood of PTSD and alcohol abuse in TTM patients, suggesting trauma may trigger or worsen TTM behaviors. Since most of our sample was female, PTSD in women can be linked to TTM. Gender-specific factors should be considered when evaluating TTM in patients, as PTSD manifests and affects individuals differently by gender.
Our results also show fatigue and difficulty running errands alone to be associated with TTM. Previous studies have found fatigue to be associated to TTM only in cases of Rapunzel’s syndrome that present with trichobezoars [17, 18]. However, while trichobezoars hint at the physical effect TTM had in these cases leading to the development of fatigue, the effects of stress and anxiety – both closely tied to TTM – should not be underestimated as additional factors when looking at TTM from an epidemiological perspective. The association between difficulty running errands alone and TTM has not been previously reported. We hypothesize that this may stem from psychosocial factors commonly observed in TTM, such as social anxiety, self-consciousness related to hair-pulling, and emotional dysregulation. Co-occurring conditions like depression and generalized anxiety disorder, as mentioned above, may further exacerbate avoidance behaviors, making routine tasks overwhelming.
This study’s limitations include potential false positives due to multiple comparisons (p < 0.05, q > 0.01) for conditions such as repetitive self-excoriation, social anxiety, stress, ADHD, fatigue, PTSD, and difficulty running errands alone. While these associations were statistically significant (p < 0.05), after adjusting for multiple comparisons (as reflected in the q values), the possibility of inflated significance due to the large number of comparisons made cannot be ruled out and these associations may require further validation. Therefore, additional research is needed to confirm their robustness and clinical relevance. Additionally, small sample sizes for certain conditions (e.g., anorexia) or inconsistent coding within the database that impacts the accuracy of sample size calculations, may potentially introduce bias in the results.
Future research may include larger samples of patients to consider comorbidities. Further investigation is needed to determine whether TTM is correlated with multiple comorbidities simultaneously.
This study highlights the need of a holistic approach in treating TTM, given its links to psychiatric comorbidities such as anxiety, depression, PTSD, and BPD, as well as substance abuse and Vitamin D deficiency. Dermatologists must assess for these conditions and collaborate with mental health professionals to address both the physical and emotional aspects of TTM.
Acknowledgments
This study used data collected from the All of Us Research Program, which is supported by the National Institutes of Health, Office of the Director: regional medical centers: 1 OT2 OD026549; 1 OT2 OD026554; 1 OT2 OD026557; 1 OT2 OD026556; 1 OT2 OD026550; 1 OT2 OD 026552; 1 OT2 OD026553; 1 OT2 OD026548; 1 OT2 OD026551; 1 OT2 OD026555; IAA#: AOD 16037; federally qualified health centers: HHSN 263201600085U; data and research center: 5 U2C OD023196; biobank: 1 U24 OD023121; the participant center: U24 OD023176; participant technology systems center: 1 U24 OD023163; communications and engagement: 3 OT2 OD023205; 3 OT2 OD023206; and community partners: 1 OT2 OD025277; 3 OT2 OD025315; 1 OT2 OD025337; 1 OT2 OD025276. In addition, the All of Us Research Program would not be possible without the partnership of its participants.
Statement of Ethics
This study used secondary data from de-identified datasets available to an individual after application. As the data was anonymized and no new participant data were collected, ethics approval was not required according to institutional and national guidelines. Written informed consent from participants was not required for the study presented in this article in accordance with local/national guidelines.
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
Funding Sources
This study was not supported by any sponsor or funder.
Author Contributions
Aarushi K. Parikh: conceptualization, methodology, software, data curation, writing – original draft, and writing – reviewing and editing. Noah Musolff: methodology and writing – review and editing. Madeline Tchack: writing – review and editing. Babar Rao: writing – review and editing and supervision.
Funding Statement
This study was not supported by any sponsor or funder.
Data Availability Statement
The registered tier dataset from the All of Us Research Program v7 was utilized for this study. Research data at the level of individual All of Us study participants are not publicly available according to the program data distribution policies. However, individuals can apply for access to the database. Further inquiries can be directed to the corresponding author.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The registered tier dataset from the All of Us Research Program v7 was utilized for this study. Research data at the level of individual All of Us study participants are not publicly available according to the program data distribution policies. However, individuals can apply for access to the database. Further inquiries can be directed to the corresponding author.