Neuroimaging procedures and related acquisitions in bipolar disorder: state of the art

Bipolar disorder (BD) is a chronic and disabling mood disorder, with significant suicide rates among psychiatric disorders. Although the pathophysiological bases of BD have not been fully elucidated yet, over the last two decades, neuroimaging research has documented specific neuroanatomic and functional abnormalities in bipolar patients. The present review was aimed to provide an updated and comprehensive overview about currently available evidence on main structural and functional alterations documented in BD by neuroimaging procedures, through a Medline research. Among the structural alterations, the most consistent ones seem to be at the level of frontal, temporal and insular cortices, amygdala and basal ganglia, having been ventriculomegaly reported as well. Magnetic resonance spectroscopy findings showed, in turn, biochemical alterations in several neurotransmitter systems. Functional neuroimaging data are quite heterogeneous with positron emission tomography and single photon emission computed tomography studies showing phase-specific abnormalities of blood flow and glucose metabolism, as well as modifications of serotonin transporter density and binding. Functional magnetic resonance imaging data documented impaired neural networks involved in emotional regulation, including anterior limbic, ventral and dorsal prefrontal regions. Taken as a whole, neuroimaging data are strongly advancing the understanding of the neural bases of BD as described in the present review.