Cortical thickness abnormalities in trichotillomania: international multi-site analysis

Abstract

Trichotillomania is a prevalent but often hidden psychiatric condition, characterized by repetitive hair pulling. The aim of this study was to confirm or refute structural brain abnormalities in trichotillomania by pooling all available global data. De-identified MRI scans were pooled by contacting authors of previous studies. Cortical thickness and sub-cortical volumes were compared between patients and controls. Patients (n = 76) and controls (n = 41) were well-matched in terms of demographic characteristics. Trichotillomania patients showed excess cortical thickness in a cluster maximal at right inferior frontal gyrus, unrelated to symptom severity. No significant sub-cortical volume differences were detected in the regions of interest. Morphometric changes in the right inferior frontal gyrus appear to play a central role in the pathophysiology of trichotillomania, and to be trait in nature. The findings are distinct from other impulsive-compulsive disorders (OCD, ADHD, gambling disorder), which have typically been associated with reduced, rather than increased, cortical thickness. Future work should examine sub-cortical and cerebellar morphology using analytic approaches designed for this purpose, and should also characterize grey matter densities/volumes.Electronic supplementary materialThe online version of this article (doi:10.1007/s11682-017-9746-3) contains supplementary material, which is available to authorized users.

White matter volume alterations in hair-pulling disorder (trichotillomania)

“…Additionally, the application of different imaging analysis tools or pipelines (the most commonly used pipelines being FSL, Freesurfer and SPM) may result in varying outcome (Fellhauer et al 2015). This, for example, was the case in the two analyses of the first pooled multi-site sample in TTM (both included about half of the participants of the present study; Chamberlain et al 2018;Isobe et al 2018), where a Freesurfer and a FSL analysis of subcortical structures did not reveal the same significant results despite the overlapping data. As a possible explanation, it has been reported that some of the variability in reported research findings may stem from differences in sensitivity and accuracy of the various analysis pipeline algorithms for grey matter, white matter or subcortical structures (Eggert et al 2012).…”

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

“…Written informed consent was obtained from all participants, and the original studies each received Institutional Review Board approvals. Conventional cortical data for many in the current sample were reported previously and the MRI dataset obtained here was largely overlapping versus that used by a previous pooled study (Chamberlain et al, 2018); the previous paper did not examine the duration of illness measure nor how it related to brain structure. Readers are referred to the original paper (and its supplement) for available information about diagnostic criteria used at each site, the scanner type, etc.…”

“…Trichotillomania is a psychiatric condition characterized by recurrent pulling out of one's own hair, leading to hair loss (APA, 2013). Brain imaging studies have suggested that the pathophysiology of trichotillomania is linked to abnormalities in both cortical regions (associated with top-down control and habit suppression) and sub-cortical neural regions (such as the dorsal striatum involved in habit generation) (Chamberlain et al, 2009, Chamberlain et al, 20101;Chamberlain et al, 2018;Grant et al, 2018;Isobe et al, 2018;Olduag et al, 2014;Slikboer et al, 2018;White et al, 2013). The findings from imaging studies in trichotillomania, however, have not always shown consistent findings (see Roos et al, 2013 no differences in trichotillomania compared to controls in white matter tracts of the fronto-striatal-thalamic pathway), and this raises the question as to whether trichotillomania is a heterogeneous disorder.…”

Trichotillomania is more related to Tourette disorder than to obsessive-compulsive disorder

“…When TTM, TS, and OCD imaging studies 16,17,92,[118][119][120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136] were compared (Table 4), striatal abnormalities were found in the three disorders. No other common abnormality is found in OCD and TTM (Table 4).…”