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Obsessive compulsive disorder (OCD) is a highly debilitating neuropsychiatric condition with estimated lifetime prevalence of 2-3%, more than twice that of schizophrenia. However, in contrast to other neuropsychiatric conditions of a comparable or lesser prevalence, relatively little is understood about the aetiology, neural substrates and cognitive profile(More)
OBJECTIVE Problems with inhibiting certain pathological behaviors are integral to obsessive-compulsive disorder (OCD), trichotillomania, and other putative obsessive-compulsive spectrum disorders. The authors assessed and compared motor inhibition and cognitive flexibility in OCD and trichotillomania for the first time, to their knowledge. METHOD The(More)
Why do we repeat choices that we know are bad for us? Decision making is characterized by the parallel engagement of two distinct systems, goal-directed and habitual, thought to arise from two computational learning mechanisms, model-based and model-free. The habitual system is a candidate source of pathological fixedness. Using a decision task that(More)
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(More)
BACKGROUND Obsessive-compulsive disorder (OCD) and trichotillomania (compulsive hair-pulling) share overlapping co-morbidity, familial transmission, and phenomenology. However, the extent to which these disorders share a common cognitive phenotype has yet to be elucidated using patients without confounding co-morbidities. AIM To compare neurocognitive(More)
Failures in cortical control of fronto-striatal neural circuits may underpin impulsive and compulsive acts. In this narrative review, we explore these behaviors from the perspective of neural processes and consider how these behaviors and neural processes contribute to mental disorders such as obsessive-compulsive disorder (OCD), obsessive-compulsive(More)
Obsessive-compulsive disorder (OCD) is characterized by repetitive thoughts and behaviors associated with underlying dysregulation of frontostriatal circuitry. Central to neurobiological models of OCD is the orbitofrontal cortex, a neural region that facilitates behavioral flexibility after negative feedback (reversal learning). We identified abnormally(More)
BACKGROUND Compulsivity is a hallmark of drug addiction and in animal models is measured by consecutive incorrect responses to a previously rewarded stimulus during reversal learning. The aim of this study was to measure behavioral and neural markers of compulsivity in stimulant-dependent individuals and to test whether these markers could be modulated by(More)
Obsessive-compulsive disorder is a prevalent and disabling lifespan disorder. Clomipramine and the SSRIs have been found to be effective across the range of symptoms, both in acute and longer-term studies. Meta-analyses have reported a larger treatment effect for clomipramine relative to the SSRIs, but this is not supported by evidence from head-to-head(More)
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(More)