Trichotillomania and Risk of Alcohol- and Drug-Related Problems

Trichotillomania is an understudied psychiatric disorder characterized by repeated hair-pulling resulting in hair loss. Little is known about the risk of problematic substance use in this patient group. In this nationwide matched cohort study, we investigated the association between trichotillomania and substance-related problems.

We linked various nationwide administrative and clinical registers in Sweden. Among 12,015,664 individuals living in the country from January 1, 1997, to December 31, 2020, we identified 1136 individuals with an ICD-10 diagnosis of trichotillomania at age ≥10 years (86.4% female, median age at first diagnosis 23.8 years [interquartile range 13.3-34.9 years]) and matched them with 11,360 unaffected individuals. The outcome was broadly defined as substance-related problems (alcohol- and drug-related disorders, suspected criminal offenses, and deaths). Stratified Cox proportional hazards regression was used to determine hazard ratios (HRs) for the association between trichotillomania and any substance-related problems.

Over a mean follow-up period of 6 years, substance-related problems were recorded for 137 (12.1%) individuals with trichotillomania and 399 (3.5%) matched individuals (crude incidence rates per 1000 person-years of 21.6 and 5.6, respectively). After controlling for sociodemographic covariates and parental substance-related problems, trichotillomania was associated with an increased relative risk of substance-related problems (HR, 3.12; 95% CI, 2.53-3.85). Adjusting also for comorbid psychiatric history did not meaningfully change the findings.

Individuals with trichotillomania had a 3-fold increased risk of substance-related problems compared with unaffected individuals. Future research should examine the mechanisms underlying this association and inform the clinical management of the dual diagnoses.