Remission from mania is associated with a decrease in amygdala activation during motor response inhibition

Neuroimaging studies of bipolar disorder (BD) have provided evidence of brain functional abnormalities during both the states of mania and remission. However, the differences in brain function between these two states are still poorly known. In the current study, we aimed to use a longitudinal design to examine the functional changes associated with symptomatic remission from mania within the brain network underlying motor response inhibition.

Using event-related functional magnetic resonance imaging (fMRI), 10 BD patients and 10 healthy subjects were imaged twice while performing a Go/NoGo task. Patients were in a manic state when they underwent the first scan and fully remitted during the second scan. A mixed-effect ANOVA was used to identify brain regions showing differences in activation change over time between the two groups.

The left amygdala was the only brain region to show a time-dependent change in activation that was significantly different between BD patients and healthy subjects. Further analyses revealed that this difference arose from the patient group, in which amygdala activation was decreased between mania and subsequent remission.

This finding suggests that a decrease in left amygdala responsiveness is a critical phenomenon associated with remission from mania. It emphasizes the relevance of longitudinal approaches for identifying neurofunctional modifications associated with mood changes in BD.