Objective Bipolar disorder (BPD) is an affective disorder marked by recurrent episodes of depressive or euphoric mood. It affects 1.5% to 4.5% of the population and has a heritability of 60–80%. The neurobiology of BPD appears to revolve around a disconnection between ventral prefrontal cortical areas and the amygdala and other subcortical limbic structures. Although secondary BPD is classically attributed to predominantly right-sided, ventral frontal lesions, there is surprisingly little evidence supporting this well-established notion. The current work aims at mapping the neuroanatomy of secondary BPD and finding anatomical “hotspots” common to all or most secondary BPD cases.
Method Subjects: patients with a clear cut history of bipolar mood swings starting after or concomitantly with a focal brain insult. Patients must have suffered at least one discrete episode of mood elevation that meets DSM-V criteria for manic or hipomanic episode. Data collection: all subjects will undergo structural 1.5 T MRI. Images from all the patients will be matched to a healthy subject's brain and will then be loaded into a specific computer software for 3-D brain reconstruction.
Results This is an ongoing project. Eight patients have been studied so-far. Four of them had right-hemisphere lesions involving dorsal fronto-parietal areas. The other patients had more extensive right-hemisphere lesions involving this and other more frontal and ventral areas.
Conclusion Secondary BPD patients may reveal brain areas with an important role in the pathophysiology of primary BPD. The study of these patients provides a clear chronological link between structural change and behavioural change, and may revel potential targets for non-invasive neuromodulatory treatment in primary BPD