Patterns of hair loss are highly variable. Areas of complete alopecia, as well as areas of thinned hair density, are common. When the scalp is involved, there may be a predilection for pulling out hair in the crown or parietal regions. There may be a pattern of nearly com- plete baldness except for a narrow perimeter around the outer margins of the scalp, par- ticularly at the nape of the neck (”tonsure trichotillomania”). Eyebrows and eyelashes may be completely absent.
Hair pulling does not usually occur in the presence of other individuals, except imme— diate family members. Some individuals have urges to pull hair from other individuals and may sometimes try to find opportunities to do so surreptitiously. Some individuals may pull hairs from pets, dolls, and other fibrous materials (e.g., sweaters or carpets).
Some individuals may deny their hair pulling to others. The majority of individuals with trichotillomania also have one or more other body-focused repetitive behaviors, including skin picking, nail biting, and lip chewing.
In the general population, the 12—month prevalence estimate for trichotillomania in adults and adolescents is 1%—2%. Females are more frequently affected than males, at a ratio of approximately 10:1. This estimate likely reﬂects the true gender ratio of the condition, al- titudes regarding appearance (e.g., acceptance of normative hair 1055 among males).
Among children with trichotillomania, males and females are more equally represented.
Hair pulling may be seen in infants, and this behavior typically resolves during early devel- opment. Onset of hair pulling in trichotillomania most commonly coincides with, or follows the onset of, puberty. Sites of hair pulling may vary over time. The usual course of trichotillo- mania is chronic, with some waxing and waning if the disorder is untreated. Symptoms may possibly worsen in females accompanying hormonal changes (e.g., menstruation, perimeno— pause). For some individuals, the disorder may come and go for weeks, months, or years at a time. A minority of individuals remit without subsequent relapse within a few years of onset.
Genetic and physiological. There is evidence for a genetic vulnerability to trichotillo— mania. The disorder is more common in individuals with obsessive-compulsive disorder (OCD) and their first-degree relatives than in the general population.
Trichotillomania appears to manifest similarly across cultures, although there is a paucity of data from non-Westem regions.
Most individuals with trichotillomania admit to hair pulling; thus, dermatopathological diagnosis is rarely required. Skin biopsy and dermoscopy (or trichoscopy) of trichotillo- mania are able to differentiate the disorder from other causes of alopecia. In trichotil- lomania, dermoscopy shows a range of characteristic features, including decreased hair density, short vellus hair, and broken hairs with different shaft lengths.
Trichotillomania is associated with distress as well as with social and occupational impair- ment. There may be irreversible damage to hair growth and hair quality. Infrequent med- ical consequences of trichotillomania include digit purpura, musculoskeletal injury (e.g., carpal tunnel syndrome; back, shoulder and neck pain), blepharitis, and dental damage (e.g., worn or broken teeth due to hair biting). Swallowing of hair (trichophagia) may lead to trichobezoars, with subsequent anemia, abdominal pain, hematemesis, nausea and vomiting, bowel obstruction, and even perforation.