Preliminary evidence for medication effects on functional abnormalities in the amygdala and anterior cingulate in bipolar disorder

Abstract

Rationale: Abnormal amygdala and frontocortical responses to emotional stimuli are implicated in bipolar disorder (BD) and have been proposed as potential treatment targets.

Objectives: The aim of this study was to investigate amygdala and frontocortical responses to emotional face stimuli in BD and the influences of mood-stabilizing medications on these responses.

Methods: Functional magnetic resonance imaging was performed while 17 BD participants (5 unmedicated) and 17 healthy comparison (HC) participants viewed faces with happy, sad, fearful, or neutral expressions.

Results: The group by stimulus-condition interaction was significant (p<0.01) for amygdala activation, with the greatest effects in the happy face condition. Relative to HC, amygdala increases were greater in unmedicated BD, but lower in medicated BD. Rostral anterior cingulate (rAC) activation was decreased in unmedicated BD compared to HC; however, BD participants taking medication demonstrated rAC activation similar to HC participants.

Conclusions: Although the sample sizes were small, these preliminary results suggest that BD is associated with increased amygdala and decreased rAC response to emotional faces. The findings also provide preliminary evidence that mood-stabilizing medications may reverse abnormalities in BD in the response of an amygdala-frontal neural system to emotional stimuli.