fMRI during affect discrimination in bipolar affective disorder

Objective: It has been hypothesized that disturbances in affect may represe nt distinct etiologic factors for bipolar affective disorder. The neural me chanisms mediating affective processes and their relationship to brain deve lopment and the pathophysiology of bipolar affective disorder remain to be clarified. Recent advances in neuroimaging techniques have made possible th e non-invasive examination of specific brain regions during cortical challe nge paradigms. This study reports findings based on fMRI data acquired duri ng fearful and happy affect recognition paradigms in patients with bipolar affective disorder and in healthy adult subjects. Methods: Prior to the scan, subjects were instructed to view the stimuli an d to identify the type of facial expression presented. Echo planar scanning was performed on a 1.5 Tesla scanner which had been retrofitted with a who le body echo planar coil, using a head coil. Results: The data indicate that in adult subjects with bipolar affective di sorder, there is a reduction in dorsolateral prefrontal cortex activation a nd an increase in amygdalar activation in response to fearful facial affect . In a healthy comparison group, signal intensity changes were not found in these regions. In addition, although the patients with bipolar affective d isorder completed the task demands, they demonstrated an impaired ability t o correctly identify fearful facial affect but not the happy facial affect displayed. Conclusion: These findings are consistent with the hypothesis that in some patients with bipolar affective disorder, there may be a reduction of front al cortical function which may be associated with affective as well as atte ntional processing deficits.