Metabolic evidence of corticolimbic dysregulation in bipolar mania

Findings from previous research on the neural substrates of mania have been variable, in part because of heterogeneity of techniques and patients. Though some findings have been replicated, the constellation of neurophysiological changes has not been demonstrated simultaneously. We sought to determine resting state cerebral metabolic changes associated with relatively severe acute mania. Resting positron emission tomography with 18fluorodeoxyglucose was performed in bipolar disorder patients with severe mania and in healthy controls. Statistical parametric mapping was used to determine regions of differential metabolism. Relative to controls, bipolar disorder patients with mania exhibited significantly decreased cerebral metabolism in both the dorsolateral prefrontal regions and the precuneus. Conversely, manic patients exhibited significant hypermetabolism in the parahippocampal complex, temporal lobe, anterior cingulate, and subgenual prefrontal cortex compared with controls. These results demonstrate simultaneous resting limbic/paralimbic hypermetabolism and prefrontal hypometabolism during mania. The findings support the hypothesis of corticolimbic dysregulation as a crucial contributor to the pathophysiology of bipolar disorder.