Trichotillomania (hair pulling disorder)

Abstract

Trichotillomania is characterized by the repetitive pulling out of one's own hair leading to hair loss and possibly functional impairment. Trichotillomania has been documented in the medical literature since the 19^th century. Prevalence studies suggest that trichotillomania is a common disorder (point prevalence estimates of 0.5%–2.0%). Although grouped with the obsessive-compulsive disorder (OCD) in the diagnostic and statistical manual of mental disorders-5, trichotillomania is distinct from OCD in many respects. For example, the treatment of trichotillomania generally employs habit reversal therapy and medication (n-acetylcysteine or olanzapine), both of which are quite different from those used to treat OCD. Conversely, some first-line treatments used for OCD (e.g., selective serotonin reuptake inhibitors) appear ineffective for trichotillomania. This article presents what is known about trichotillomania and the evidence for a variety of treatment interventions.

INTRODUCTION

Trichotillomania (hair-pulling disorder) is an often debilitating psychiatric condition characterized by recurrent pulling out of one's own hair, leading to hair loss, and marked functional impairment.[1,2] Although discussed in the medical literature for over a century,[3] trichotillomania was not officially included as a mental health disorder in the American psychiatric association's diagnostic and statistical manual of mental disorders (DSM) until the DSM-III-R (1987) when it was classified as an impulse control disorder not elsewhere classified. In the 5^th edition of the DSM (DSM-5),[4] trichotillomania was included in the chapter on obsessive-compulsive and related disorders with obsessive-compulsive disorder (OCD), excoriation disorder, body dysmorphic disorder, and hoarding disorder. The current diagnostic criteria for trichotillomania are as follows: pulling of hair which results in hair loss; attempts to either decrease or stop pulling; significant distress or impairment; and the pulling cannot be attributed to another medical or psychiatric condition.[4]

EPIDEMIOLOGY AND CLINICAL CHARACTERISTICS

Nationwide epidemiological studies of trichotillomania are lacking, smaller studies, usually conducted in university settings, have found a lifetime prevalence of trichotillomania to be around 0.6%;[1] and point prevalence to be 0.0%–3.9%.[5,6,7,8] Because people with trichotillomania are often ashamed and embarrassed about their condition, these numbers may actually reflect underestimates of the true population prevalence. In adults, trichotillomania appears to have a large female preponderance (4:1 female:male), a sex ratio that is unique among psychiatric disorders.[9] In childhood, sex distribution has been found to be equal.[10]

Hair pulling appears to be quite common and often presents along with a continuum from mild-to-severe. The most common sites pulled include the scalp, eyebrows, and eyelashes; although, pulling from other areas of the body is common.[11] Pulling from multiple sites is not uncommon and pulling episodes can last from a few minutes to several hours.[11]

The onset of hair pulling is generally in late childhood or early adolescence.[11] Due to the developmental period when the disorder begins, trichotillomania is often associated with reduced self-esteem and quality of life and avoidance of social situations (for example, getting haircuts, swimming, being outside on a windy day, sporting activities, or dating).[12,13] Cues to pulling may include stress, boredom, or “downtime.” In addition, many people not being fully aware of their pulling behaviors also referred to as “automatic” pulling and comprise a more habitual form of the disorder.[2] Approximately 10%–20% of people with trichotillomania eat their hair after pulling it (“trichophagia”), which can result in gastrointestinal obstruction and the formation of intestinal hair-balls (“trichobezoars”) which can require surgical intervention.[14]

COMORBIDITY

Comorbid psychiatric conditions, especially depression and/or anxiety (lifetime histories of which are seen in over 50% of patients) are extremely common in trichotillomania.[15,16] In fact, lifetime and current major depressive disorder occur in between 29% and 52% of patients and OCD has been found to co-occur in over 26% of patients with trichotillomania. Trichotillomania also frequently co-occurs with skin picking disorder, and when it does, people tend to have more severe trichotillomania symptoms.[17]

NEUROBIOLOGY: SELECT RECENT DEVELOPMENTS

Data regarding the pathophysiology of trichotillomania are limited, but there is a familial component. Several family studies have reported elevated rates of trichotillomania in first-degree relatives of probands with trichotillomania, along with elevated rates of mood and anxiety disorders.[18] In a recent study, Keuthen et al. found that the relatives of probands with trichotillomania had higher recurrence risk estimates for hair pulling.[19]

Animal models represent useful tools for investigating the pathophysiology of trichotillomania particularly those which mimic the behavioral and clinical manifestations of the disorder. Three models in particular exhibit markedly elevated grooming: the HoxB8 knockout mouse,[20] the SAPAP3 knockout mouse,[21] and the SliTrk5 knockout mouse.[22] The potential relevance of SAPAP3, in particular, to trichotillomania, is reinforced by the finding that rare variations in the SAPAP3 gene are associated with human disorders such as hair pulling.[23] The hoxb8 gene is ordinarily expressed in mice orbitofrontal cortex and striatum, regions also heavily implicated in the pathophysiology of OCD in humans.[24]

A few small neuroimaging studies have examined possible structural brain findings in trichotillomania, most of which have been “region-of-interest.” A recent multi-site international study of cortical thickness and sub-cortical volumes (76 people with trichotillomania compared to 41 controls) found that trichotillomania patients showed excess cortical thickness in a cluster maximal at right inferior frontal gyrus and appear to play a central role in the pathophysiology of trichotillomania and to be a trait in nature.[25] These findings are distinct from OCD.

Another recent multi-site study attempted to elucidate subcortical morphometric abnormalities, including localized curvature changes, in trichotillomania. A pooled sample of 68 individuals with trichotillomania and 41 healthy controls found significant volumetric reductions in trichotillomania in the right amygdala and left putamen. Localized shape deformities were found in bilateral nucleus accumbens, bilateral amygdala, right caudate, and right putamen. These structural abnormalities of subcortical regions appear to be involved in affect regulation, inhibitory control, and habit generation.[26]

In terms of other biological research in trichotillomania, a recent study examined hormonal markers in adolescent girls with trichotillomania. Trichotillomania generally has its onset at puberty and is far more common in females. In addition, several years ago, Keuthen et al. found that 53.3% of a sample of 45 adults with trichotillomania reported that they experienced symptom exacerbation of pulling the week before menstruation.[27] The recent study examining the role of sex hormones in eleven adolescent girls with trichotillomania found that lower progesterone was associated with more severe symptoms and lower levels of all hormones were associated with worse overall functioning.[28]

TREATMENT

Psychotherapy

Various components of cognitive behavioral therapy are the most widely recognized and efficacious treatments for trichotillomania. For example, habit reversal therapy (HRT) is relatively well established in the treatment of trichotillomania, with large effect size versus control conditions. HRT is first-line treatment and focuses on: awareness training (encouraging awareness of situations that can precede pulling episodes), relaxation training (since anxiety and stress are commonly reported triggers for hair pulling episodes), competing response training (encouraging unwanted pulling behaviors to be replaced with a less conspicuous action), motivation procedures, and generalization training.[29,30]

Elements of dialectical behavior therapy have been added to more traditional cognitive behavioral approaches for the treatment of trichotillomania. The therapy consists of mindfulness training (e.g., patients are taught to experience urges or negative emotions as they occur in the present moment and learn to allow them to pass without pulling), teaching patients skills to regulate negative emotions without pulling, and building a distress tolerance (e.g., tolerating urges or stressful events without pulling).[31]

Acceptance and commitment therapy is a subsidiary component of HRT in which patients are asked to experience urges to pull and accept the urge without acting on it. The negative emotions involved with pulling are also engaged but not acted upon. The idea is that understanding, feeling, and experiencing the fact that the individuals do not have to respond to an urge or emotion can help the patient to feel more in control of their pulling.[32]

Finally, exposure therapy, borrowed from the world of OCD, has been used in preliminary research to help with trichotillomania.[33] The therapy consists of a brief, 4-component approach based on the conceptualization that hair-pulling is maintained by negative reinforcement similar to compulsions associated with OCD. The first component examines the individual's hair-pulling pattern; the second component involves the generation of a hair-pulling hierarchy; the third component uses exposures based on the individual's hierarchy; and the fourth component addresses emotion dysregulation.

Pharmacotherapy

There are no medications approved by any regulatory agencies for the treatment of trichotillomania. Having said that, several studies examining the safety and efficacy of different pharmacological interventions have been conducted.[34] Pharmacotherapies which have indicated efficacious outcomes in trichotillomania include n-acetylcysteine (NAC), clomipramine, olanzapine, and dronabinol; although, each of these treatments has been shown to be efficacious in relatively small samples of clinical trial patients. In the case of NAC, two double-blind placebo-controlled studies for trichotillomania using a dose of 1200 mg twice a day produced conflicting results. The study in adults demonstrated greater efficacy than placebo, whereas the same study in children did not.[35,36] The studies raise the question of whether the disorder may be different in these age groups and may even change over time. Side effects with NAC are generally mild and usually only involve some bloated feelings and flatulence. The antipsychotic, olanzapine, has also been studied in one small (n = 23) 12 weeks, double-blind, placebo-controlled trial.[37] Olanzapine (mean dose of 10.8 mg/day) significantly reduced symptoms of trichotillomania compared to placebo, but olanzapine has been associated with metabolic syndrome and hence, this adverse side effect profile needs to be considered when prescribing this medication. Finally, serotonin reuptake inhibitors are frequently prescribed for the treatment of trichotillomania, but meta-analyses have shown that only clomipramine appears to be effective and that the effect is relatively small.[34,38]

Control of the hair pulling appears to be critical for maintaining long-term health and quality of life. Based on research findings, NAC in doses of 1200 mg twice a day appears to be the most promising option without significant side effects. Dopamine blockers such as olanzapine may also be promising, but side effects need to be carefully monitored.

SUMMARY

If untreated, trichotillomania is a chronic illness that often results in substantial psychosocial dysfunction, and that can, in rare cases, lead to life-threatening medical problems. Greater understanding of the neurobiology of trichotillomania is needed to improve treatment approaches.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.