Dissociable functional connectivity changes during the Stroop task relating to risk, resilience and disease expression in bipolar disorder

Abstract

Reduced cognitive control is considered a core feature of bipolar disorder (BD). Abnormalities in ventrolateral prefrontal cortex (VLPFC) and other functionally linked regions that underpin cognitive control during the Stroop Colour Word Task (SCWT) have been reported in patients with BD and their relatives. In this functional magnetic resonance study we used psychophysiological interaction analysis to examine functional connectivity during the SCWT in 39 euthymic BD patients, 39 of their first-degree relatives (25 with no Axis I disorders and 14 with major depressive disorder) and 48 healthy controls. The aim of this study was to identify potential diagnosis-specific functional connectivity changes differentiating patients with BD from their relatives with MDD, as well as functional connectivity correlates of resilience in relatives of BD patients who remain well. Psychophysiological interactions in healthy controls revealed a negative functional connectivity between the VLPFC and the ventral anterior cingulate cortex and insula and a positive connectivity between the VLPFC and the caudate and parietal cortices. Abnormalities in fronto-insular connectivity emerged as a key correlate of predisposition and disease expression for BD. Reduced fronto-cingulate connectivity was also observed in association with predisposition to BD irrespective of clinical outcome. BD patients and their MDD relatives showed additional abnormalities in frontal-basal ganglia connectivity while increased coupling between the ventral and dorsal lateral PFC was observed in relatives without any Axis I disorder. These findings suggest that during the SCWT the VLPFC and subcortical regions are involved in a dynamic interplay. Breakdown in these interactions is associated with risk and disease expression for mood disorders while increased functional coupling between dorsal and ventral prefrontal regions may reflect adaptive functional changes associated with resilience.