Cognitive neuroscience and brain imaging in bipolar disorder

Bipolar disorder is characterized by a combination of state-related changes in psychological functíon that are restricted to illness episodes, coupled with trait-related changes that persist through periods of remission, irrespective of symptom status. This article reviews studies that have investigated the brain systems involved in these state-and trait-related changes, using two techniques: (i) indirect measures of neurocognitive function, and (ii) direct neuroimaging measures of brain function during performance of a cognitive task. Studies of neurocognitive function in bipolar disorder indicate deficits in three core domains: attention, executive function, and emotional processing. Functional imaging studies implicate pathophysiology in distributed neural circuitry that includes the prefrontal and anterior cingulate cortices, as well as subcortical limbic structures including the amygdala and the ventral striatum. Whilst there have been clear advances in our understanding of brain changes in bipolar disorder, there are limited data in bipolar depression, and there is limited understanding of the influence of clinical variables including medication status, illness severity, and specific symptom dimensions.