Reduced brain white matter integrity in trichotillomania: a diffusion tensor imaging study.

CONTEXT: Trichotillomania is an Axis I disorder characterized by repetitive, pathological hair pulling. OBJECTIVE: To assess the integrity of white matter tracts in subjects with the disorder. DESIGN: Between-group comparison using permutation cluster analysis, with stringent correction for multiple comparisons. SETTING: Academic psychiatry department. PARTICIPANTS: Eighteen volunteers meeting DSM-IV criteria for trichotillomania and 19 healthy control subjects. MAIN OUTCOME MEASURES: Fractional anisotropy (measured using diffusion tensor imaging), trichotillomania disease severity (Massachusetts General Hospital Hairpulling Scale score), and dysphoria (Montgomery-Asberg Depression Rating Scale score). RESULTS: Subjects with trichotillomania exhibited significantly reduced fractional anisotropy in anterior cingulate, presupplementary motor area, and temporal cortices. Fractional anisotropy did not correlate significantly with trichotillomania disease severity or depressive mood scores. CONCLUSIONS: These data implicate disorganization of white matter tracts involved in motor habit generation and suppression, along with affective regulation, in the pathophysiology of trichotillomania.

Grey matter abnormalities in trichotillomania: morphometric magnetic resonance imaging study.

BACKGROUND: Trichotillomania (repetitive hair-pulling) is an Axis I psychiatric disorder whose neurobiological basis is incompletely understood. Whole-brain trichotillomania neuroimaging studies are lacking. AIMS: To investigate grey and white matter abnormalities over the whole brain in patients with trichotillomania. METHOD: Eighteen patients with DSM-IV trichotillomania and 19 healthy controls undertook structural magnetic resonance imaging after providing written informed consent. Differences in grey and white matter were investigated using computational morphometry. RESULTS: Patients with trichotillomania showed increased grey matter densities in the left striatum, left amygdalo-hippocampal formation, and multiple (including cingulate, supplementary motor, and frontal) cortical regions bilaterally. CONCLUSIONS: Trichotillomania was associated with structural grey matter changes in neural circuitry implicated in habit learning, cognition and affect regulation. These findings inform animal models of the disorder and highlight key regions of interest for future translational research.

Impaired cognitive flexibility and motor inhibition in unaffected first-degree relatives of patients with obsessive-compulsive disorder.

OBJECTIVE: Obsessive-compulsive disorder (OCD) is highly heritable. Attempts to delineate precise genetic contributions have met with limited success. There is an ongoing search for intermediate cognitive brain markers (endophenotypes) that may help clarify genetic contributions. The aim was to assess inhibitory control processes in unaffected first-degree relatives of OCD patients for the first time with objective tests. METHOD: The Intradimensional/Extradimensional Shift, Stop-Signal, and Cambridge Gamble tasks were administered to 20 unaffected first-degree relatives, 20 OCD patient probands with washing/checking symptoms, and 20 healthy matched comparison subjects without a family history of OCD. RESULTS: Unaffected first-degree relatives and OCD patient probands showed cognitive inflexibility (extradimensional set shifting) and motor impulsivity (stop-signal reaction times). Decision making (Cambridge Gamble task) was intact. CONCLUSIONS: Deficits in cognitive flexibility and motor inhibition may represent cognitive endophenotypes for OCD. Such measures will play a key role in understanding genotype/phenotype associations for OCD and related spectrum conditions.