Where, when, how high, and how long? The hemodynamics of emotional response in psychotropic-naïve patients with adolescent bipolar disorder.

BACKGROUND: In response to emotional faces, patients with adolescent bipolar disorder (ABD) exhibit increased neural activity in subcortical emotional processing regions (e.g., amygdala, ventral striatum) and variable prefrontal activity. We extend previous research by identifying cortical and subcortical regions showing altered hemodynamic response shapes in ABD relative to healthy controls (HC).
METHODS: ABD (N=65) and matched HC (N=79) completed a slow event-related affective hemodynamic probe task that required indicating the gender of fearful and neutral faces. An informed basis set in SPM8 evaluated shape variations of the hemodynamic responses to these faces.
RESULTS: Patients with ABD showed higher activity for fearful relative to neutral faces in the amygdala and prefrontal cortex and a delayed hemodynamic response to fearful faces in dorsolateral and ventrolateral prefrontal cortices (PFC), as well as bilateral amygdala and caudate. Furthermore, the ABD group, relative to HC, showed a prolonged response to fearful faces in right dorsolateral PFC. Clinical measures of mania and depression severity correlated with increased processing delays in the amygdala and striatum. LIMITATIONS: By design, the task contained fewer, more widely-spaced stimuli, possibly reducing its power to detect group differences. The use of fearful faces makes comparisons with prior literature in ABD somewhat more difficult.
CONCLUSIONS: The ABD group engaged in enhanced neural processing of the fearful faces which was associated with increasingly severe manic/mixed mood states. These exploratory findings could help elucidate a "biosignature" of emotion-attention interactions in ABD and present a potential target for reversal with medication treatment.