Intrinsic functional connectivity during continuous maintenance and suppression of emotion in bipolar disorder

Resting-state connectivity studies, which examine unconstrained low frequency BOLD fluctuations, have reported inconsistent abnormalities in bipolar disorder (BP). In this study, we investigated intrinsic brain connectivity under the constraints of a Continuous Emotion Regulation Task (CERT) in BP patients in depressed (BPD) and manic (BPM) states, along with healthy control participants. Medication-free participants, with either a diagnosis of BP (BPD = 27, BPM = 30) or healthy controls (N = 33) were included. We collected 2 fMRI scans using the CERT paradigm, in which participants continuously watched negative pictures and either maintained emotions (MAINTAIN) or suppressed emotion using reappraisal techniques (SUPPRESS). Network-based statistic and graph theory analyses were examined for (i) the main effect of condition (within-group) and (ii) group and condition interactions. In healthy participants, MAINTAIN largely involved occipital and parietal cortices (p < .001), whereas SUPPRESS also recruited the frontal and cingulate cortices (p = .023). The interaction between group (BPD vs. BPM) and condition revealed a network involving the inferior frontal lobe which was stronger during MAINTAIN for BPD and during SUPPRESS for BPM (p = .037). Graph theory properties (i.e., clustering coefficient) for key nodes also evidenced significant group by condition interactions. We observed BP-related changes in network properties involved in normal and abnormal emotion regulation, which provide insights into the neural bases for affective disturbances in BP.