Objective: Functional magnetic resonance imaging (fMRI) studies have documented abnormalities in the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex in bipolar disorder in the context of working memory tasks. It is increasingly recognized that DLPFC regions play a role in mood regulation and the integration of emotion and cognition. The purpose of the present study was to investigate with fMRI the interaction between acute sadness and working memory functioning in individuals with bipolar disorder.
Methods: Nine depressed individuals with DSM-IV bipolar I disorder (BP-I) and 17 healthy control participants matched for age, gender, education, and IQ completed a 2-back working memory paradigm under no mood induction, neutral state, or acute sadness conditions while undergoing fMRI scanning. Functional MRI data were analyzed with SPM2 using a random-effects model.
Results: Behaviorally, BP-I subjects performed equally well as control participants on the 2-back working memory paradigm. Compared to control participants, individuals with BP-I were characterized by more sadness-specific activation increases in the left DLPFC (BA 9/46) and left dorsal anterior cingulate (dACC).
Conclusions: Our study documents sadness-specific abnormalities in the left DLPFC and dACC in bipolar disorder that suggest difficulties in the integration of emotion (sadness) and cognition. These preliminary findings require further corroboration with larger sample sizes of medication-free subjects.