Neuroanatomical studies on bipolar disorder

Background Neuroimaging data showing structural and functional brain abnorm alities in mood disorders suggest that brain alterations at the neurohistol ogical level may underlie the macropathology seen by imaging in vivo. Aims To summarise recent postmortem studies on affective disorders. with a focus on bipolar disorder. Method Literature review and discussion of results from volumetric. cyto-ar chitectural and immunohistochemical analyses. Results Basal ganglia are smaller in patients with depression irrespective of diagnostic polarity. In addition, higher neuron numbers have been report ed in the locus caeruleus of patients with bipolar disorder compared with t hose with unipolar depression. Patients with bipolar as well as unipolar il lness show subtle structural deficits in the dorsal raphe. Histological dat a are consistent with a regional reduction in the synthesis of noradrenalin and serotonin, which appears to be compensated by antidepressants. Conclusion Preliminary results suggest that, aside from functional dysregul ation, subtle structural abnormalities in the brain may contribute to the p athogenesis of mood disorders.