Neuroanatomical studies on bipolar disorder.

Background Neuroimaging data showing structural and functional brain abnormalities in mood disorders suggest that brain alterations at the neurohistological level may underlie the macropathology seen by imaging in vivo. Aims To summarise recent post-mortem studies on affective disorders, with a focus on bipolar disorder. Method Literature review and discussion of results from volumetric, cyto-architectural and immunohistochemical analyses. Results Basal ganglia are smaller in patients with depression irrespective of diagnostic polarity. In addition, higher neuron numbers have been reported in the locus caeruleus of patients with bipolar disorder compared with those with unipolar depression. Patients with bipolar as well as unipolar illness show subtle structural deficits in the dorsal raphe. Histological data 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 dysregulation, subtle structural abnormalities in the brain may contribute to the pathogenesis of mood disorders.