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Trichotillomania, or hair-pulling disorder, is one of a family of disorders called body-focused repetitive behaviours (BFRBs), which also include disordered skin-picking (dermotillomania) and nail-biting (onychophagia). The disorders affect 1%-2% of the population, cause high levels of distress and have high levels of comorbidity with other psychiatric diagnoses. The key facts and figures are briefly reviewed and some important points are further explored: (1) BFRBs are associated with psychological distress, but are distinct from other diagnoses, (2) The pathological behaviours mirror excessive self-grooming behaviours in other species, and may relate to immune-system mediated feedback loops, and (3) The resulting behaviours are stigmatised and cause intense shame and isolation for those who suffer, which might in itself maintain the feedback loop. These observations lead to the hypothesis that the core disorder is one of pathological grooming, which may have a basis in an immune response, with shame being both a consequence and a maintainer of the disorder. The major barrier to testing the hypotheses and potential interventions remains the stigma that keeps these disorders, and those who suffer from them, in the shadows.

Original publication




Journal article


BMJ Ment Health

Publication Date





Adult psychiatry, Child & adolescent psychiatry, Impulse control disorders, Animals, Trichotillomania, Neurosciences, Anxiety, Grooming, Nail Biting