Bipolar Disorder (BD) is associated with structural and functional abnormalities in prefrontal and limbic areas implicated in emotional processing. Lamotrigine (LTG) has been shown to improve depressive features in BD although its mechanism of therapeutic action is not known. The current study examined the possibility that LTG may improve functional activation within the neural circuitry involved in emotional processing.

We used functional Magnetic Resonance Imaging to examine changes in patterns of brain activation in 12 stable BD patients (a) compared to healthy controls when medication free and (b) after 12 weeks of Lamotrigine monotherapy whilst performing a sad facial affect recognition task on both occasions.

At baseline, compared to controls, BD patients showed overactivity in response to sad facial affect recognition in temporal lobe regions and under-activity in dorsal medial and right ventrolateral PFC and the dorsal cingulate gyrus. After 4 weeks of LTG monotherapy, patients showed reduced activation in temporal regions and increased neural response in dorsomedial and ventrolateral prefrontal regions.

This preliminary evidence suggests the possibility that LTG may enhance functional activation within prefrontal regions responsible for emotional self-regulation.

This study was supported by an unrestricted grant from GlaxoSmithKline