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Trichotillomania (hair-pulling disorder) is characterized by the repetitive pulling out of one's own hair, and is classified as an Obsessive-Compulsive Related Disorder. Abnormalities of the ventral and dorsal striatum have been implicated in disease models of trichotillomania, based on translational research, but direct evidence is lacking. The aim of this study was to elucidate subcortical morphometric abnormalities, including localized curvature changes, in trichotillomania. De-identified MRI scans were pooled by contacting authors of previous peer-reviewed studies that examined brain structure in adult patients with trichotillomania, following an extensive literature search. Group differences on subcortical volumes of interest were explored (t-tests) and localized differences in subcortical structure morphology were quantified using permutation testing. The pooled sample comprised N=68 individuals with trichotillomania and N=41 healthy controls. Groups were well-matched in terms of age, gender, and educational levels. Significant volumetric reductions were found in trichotillomania patients versus controls in right amygdala and left putamen. Localized shape deformities were found in bilateral nucleus accumbens, bilateral amygdala, right caudate and right putamen. Structural abnormalities of subcortical regions involved in affect regulation, inhibitory control, and habit generation, play a key role in the pathophysiology of trichotillomania. Trichotillomania may constitute a useful model through which to better understand other compulsive symptoms. These findings may account for why certain medications appear effective for trichotillomania, namely those modulating subcortical dopamine and glutamatergic function. Future work should study the state versus trait nature of these changes, and the impact of treatment. Keywords: Trichotillomania, Impulse, Impulsivity, Compulsivity, MRI, Neuroimaging

Abstract Background A promising approach to reducing the phenotypic heterogeneity of psychiatric disorders involves the identification of homogeneous subtypes. Careful study of comorbidity in obsessive‐compulsive disorder (OCD) contributed to the identification of the DSM‐5 subtype of OCD with tics. Here we investigated one of the largest available cohorts of clinically diagnosed trichotillomania (TTM) to determine whether subtyping TTM based on comorbidity would help delineate clinically meaningful subgroups. Methods As part of an ongoing international collaboration, lifetime comorbidity data were collated from 304 adults with pathological hair‐pulling who fulfilled criteria for DSM‐IV‐TR or DSM‐5 TTM. Cluster analysis (Ward's method) based on comorbidities was undertaken. Results Three clusters were identified, namely Cluster 1: cases without any comorbidities (n = 63, 20.7%) labeled “simple TTM,” Cluster 2: cases with comorbid major depressive disorder only (N = 49, 16.12%) labeled “depressive TTM,” and Cluster 3: cases presenting with combinations of the investigated comorbidities (N = 192, 63.16%) labeled “complex TTM.” The clusters differed in terms of hair‐pulling severity (F = 3.75, p = .02; Kruskal–Wallis [KW] p

Objective: To perform a cross-cultural comparison of gambling disorder (GD) in women from Brazil and the United States, two countries with pronounced social and cultural differences. We hoped to produce insight into the impact of cultural influences on the presentation of GD in women, which may be useful for the development of culturally-sensitive interventions. Method: We assessed 681 women with GD: 406 from a Brazilian sample and 275 from a U.S. sample. We assessed demographic and gambling behavior variables in addition to co-occurring psychiatric disorders. Results: Fewer Brazilian participants were Caucasian (73.3 vs. 91.3%; p = 0.022). Also, Brazilian women had lower levels of education (59.9% with high school or less vs. 44.4%; p < 0.001), and were more likely to have a current partner (54.9 vs. 43.4%; p = 0.003). Brazilian gamblers also reported lower urge scores (6.6±4.3 vs. 11.6±2.4; p < 0.001) and higher chasing rates (89.1 vs. 80.0%; p = 0.002). Brazilian gamblers reported higher rates of bingo gambling (19.2 vs. 5.7%; p < 0.001), but lower rates of card game gambling (5.8 vs. 23.1%; p < 0.001). Finally, Brazilian gamblers were more likely to endorse a history of major depressive disorder (36.9 vs. 24.4%; p = 0.001). Conclusions: This study reinforces the need for further general cross-cultural research on GD and particularly for studies investigating how gender mediates these differences. Finally, the differences noted in this analysis suggest that the findings of predominantly Anglo-Saxon cultures may not be generalizable to other world populations.