Significance of family history in understanding and subtyping trichotillomania

Background and aims: The existence of subtypes of trichotillomania (TTM) have long been hypothesized, and recent studies have further elucidated characteristic subtypes of TTM and possible ramifications of subtyping for treatment. In clinical applications of subtyping for treatment of TTM, family history (FH) of psychiatric disorders in patients may serve as a tool to differentiate disorder presentations and inform care. We compared prevalence of psychiatric illnesses in first-degree relatives of participants with TTM and healthy controls, respectively, in a large sample, and examined associations between those psychiatric disorders that were significantly different in the FH between groups and measures of disability, severity, and neuropsychological constructs.

Methods: We compared FHs of 152 participants (mean age = 29.9) with TTM and 71 healthy controls (mean age = 29.6), utilizing chi-squared tests to determine which psychiatric illnesses were more prevalent in FHs of participants with TTM. We then used two-tailed t-tests to compare TTM participants with those more prevalent FHs to participants without those FHs on measures of disorder severity, disability, and neuropsychological constructs.

Findings: Obsessive-compulsive disorder (OCD), TTM, skin picking disorder (SPD), and major depressive disorder (MDD) were significantly more frequent in first-degree relatives (p < 0.0033) of TTM participants than those of healthy controls. TTM participants with a FH of OCD scored significantly higher on measures of impulsivity and lower on measures of distress tolerance. Those with FH of TTM, SPD, and MDD did not differ significantly across measured variables.

Conclusion: OCD, TTM, SPD, and MDD are more prevalent in the FHs of people with TTM, as compared to healthy controls. TTM participants with a family history of OCD may be more likely to demonstrate decreased distress tolerance and increased impulsivity. In all, as understanding of TTM subtypes develops, the FH may prove a useful tool in delineating subtypes and informing care.