Duration of illness and cortical thickness in trichotillomania: Preliminary evidence for illness change over time.

Trichotillomania is a psychiatric condition characterized by repetitive pulling out of one's hair, leading to marked functional impairment. The aim of this study was to examine the association between duration of trichotillomania (defined as time between initial age of onset and current age) and structural brain abnormalities by pooling all available global data. Authors of published neuroimaging studies of trichotillomania were contacted and invited to contribute de-identified MRI scans for a pooled analysis. Freesurfer pipelines were used to examine whether cortical thickness and sub-cortical volumes were associated with duration of illness in adults with trichotillomania. The sample comprised 50 adults with trichotillomania (100% not taking psychotropic medication; mean [SD] age 34.3 [12.3] years; 92% female). Longer duration of illness was associated with lower cortical thickness in bilateral superior frontal cortex and left rostral middle frontal cortex. Volumes of the a priori sub-cortical structures of interest were not significantly correlated with duration of illness (all p > 0.05 uncorrected). This study is the first to suggest that trichotillomania is associated with biological changes over time. If this finding is supported by prospective studies, it could have important implications for treatment (i.e. treatment might need to be tailored for stage of illness). Viewed alongside prior work, the data suggest that brain changes in trichotillomania may be differentially associated with vulnerability (excess thickness in right inferior frontal cortex) and with chronicity (reduced thickness in medial and superior frontal cortex). Longitudinal research is now indicated.
Competing Interests: Conflict of interest Dr. Grant has received research grants from TLC Foundation, and Takeda Pharmaceuticals. Dr. Grant receives yearly compensation from Springer Publishing for acting as Editor-in-Chief of the Journal of Gambling Studies and has received royalties from Oxford University Press, American Psychiatric Publishing, Inc., Norton Press, and McGraw Hill. Dr. Chamberlain's time on this study was supported by a Wellcome Trust Clinical Fellowship (110049/Z/15/Z). Dr. Chamberlain consults for Cambridge Cognition, Shire, Promentis, and Ieso Digital Health. Dr. Chamberlain receives a stipend for his work as Associate Editor at Neuroscience and Biobehavioral Reviews; and at Comprehensive Psychiatry. Dr Keuthen is on the Scientific Advisory Board of the TLC Foundation for BFRBs and currently receives funding from its BFRB Precision Medicine Initiative. She receives royalties from New Harbinger, Inc. In the past 3 years, Dr. Stein has received research grants and/or consultancy honoraria from Biocodex, Lundbeck, Servier, and Sun. Dr. Lochner reports no potential conflicts of interest.
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