254 Obsessive-Compulsive and Related Disorders
Neurodevelopmental disorders. In neurodevelopmental di sorders, hair pulling may
meet the definition of stereotypies (e.g., in stereotypic movement disorder). Tics (in tic dis-
orders) rarely lead to hair pulling.
Psychotic disorder. Individuals with a psychotic disord er may remove hair in response
to a delusion or hallucinati on. Trichotillomania is not diagnosed in such cases.
Another medical condition. Trichotillomania is not diagnosed if the hair pulling or hair
loss is attributable to another medical conditio n (e.g., inflammation of the skin or other der-
matological conditions). Other causes of scarri ng alopecia (e.g., alop ecia areata, androgenic
alopecia, telogen effluvium) or nonscarring al opecia (e.g., chronic discoid lupus erythema-
tosus, lichen planopilaris, central centrifugal cicatricial alopecia, pseudopelade, folliculitis
decalvans, dissecting folliculitis, acne keloidalis nuchae) should be considered in individu-
als with hair loss who deny hair pulling. Skin biopsy or dermoscopy ca n be used to differ-
entiate individuals with tric hotillomania from those with  dermatological disorders.
Substance-related disorders. Hair-pulling symptoms may be exacerbated by certain
substances—for example, stimulants—but it is less likely that substances are the primary
cause of persistent hair pulling. 
Comorbidity
Trichotillomania is often accompanied by ot her mental disorders, most commonly major
depressive disorder and excoriation (skin- picking) disorder. Repetitive body-focused