Predictors of Treatment Response in Bipolar Disorders: Evidence From Clinical and Brain Imaging Studies

The clinical features of bipolar disorders can be correlated with responses to medications. Patientswho respond to lithium, for example, often present differently from those who respond todivalproex or carbamazepine, but the correlations are relatively modest. Brain-imaging tools, suchas positron emission tomography (PET), single photon emission computed tomography (SPECT),and functional magnetic resonance imaging (fMRI), can relate brain function to clinical featuresand medication responses. For example, in depression, it appears that prefrontal cortical functionis decreased while subcortical anterior paralimbic activity is increased. Preliminary evidence suggeststhat baseline metabolism increases and decreases in the left insula may be associated withcarbamazepine and nimodipine responses, respectively, and that cerebral lithium concentrationsmay correlate with antimanic effects. Although it is not yet a clinical tool for bipolar disorders,brain imaging provides useful research data to understand the fundamental neurobiology of mooddisorders and to more effectively target therapeutics.