Impaired response inhibition and excess cortical thickness as candidate endophenotypes for trichotillomania

• Published in: Journal of psychiatric research Vol. 59; pp. 167 - 173
• Main Authors: Odlaug, Brian L., Chamberlain, Samuel R., Derbyshire, Katie L., Leppink, Eric W., Grant, Jon E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Aged; Biological and medical sciences; Cerebral Cortex - pathology; Cognition; Compulsivity; Dermatology; Endophenotype; Endophenotypes; Female; Hair and nails disorders; Humans; Image Processing, Computer-Assisted; Imaging; Impulsivity; Inhibition (Psychology); Learning Disorders - etiology; Magnetic Resonance Imaging; Male; Medical sciences; Middle Aged; Miscellaneous; Neuropsychological Tests; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Social behavior disorders. Criminal behavior. Delinquency; Trichotillomania; Trichotillomania - complications; Trichotillomania - pathology; Young Adult; Compulsivity; Impulsivity; Cognition; Trichotillomania; Imaging; Endophenotype; Skin disease; Cerebral cortex; Impulse control disorder; Central nervous system; Personality; Layer thickness; Encephalon; Hair (head); Compulsion; Psychopathology; Inhibition
• DOI: 10.1016/j.jpsychires.2014.08.010
• ISSN: 0022-3956; 1879-1379

Trichotillomania is characterized by repetitive pulling out of one's own hair. Impaired response inhibition has been identified in patients with trichotillomania, along with gray matter density changes in distributed neural regions including frontal cortex. The objective of this study was to evaluate impaired response inhibition and abnormal cortical morphology as candidate endophenotypes for the disorder. Subjects with trichotillomania (N = 12), unaffected first-degree relatives of these patients (N = 10), and healthy controls (N = 14), completed the Stop Signal Task (SST), a measure of response inhibition, and structural magnetic resonance imaging scans. Group differences in SST performance and cortical thickness were explored using permutation testing. Groups differed significantly in response inhibition, with patients demonstrating impaired performance versus controls, and relatives occupying an intermediate position. Permutation cluster analysis revealed significant excesses of cortical thickness in patients and their relatives compared to controls, in right inferior/middle frontal gyri (Brodmann Area, BA 47 & 11), right lingual gyrus (BA 18), left superior temporal cortex (BA 21), and left precuneus (BA 7). No significant differences emerged between groups for striatum or cerebellar volumes. Impaired response inhibition and an excess of cortical thickness in neural regions germane to inhibitory control, and action monitoring, represent vulnerability markers for trichotillomania. Future work should explore genetic and environmental associations with these biological markers. •First study to evaluate biological vulnerability markers for trichotillomania.•People with trichotillomania and their first-degree relatives have similar biologies.•These findings appear largely distinct from those identified for OCD.