Investigating the neural basis of cognitive control dysfunction in mood disorders

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Cognitive control dysfunction is a persistent feature in both bipolar disorder (BP) and major depressive disorder (MDD), even during remission.
• Existing research has not clarified whether these disorders share common or distinct neural disruptions in cognitive control.

Purpose of the Study:

• To investigate the common or distinct disruptions in cognitive control function and their neural underpinnings in asymptomatic BP and remitted MDD participants.
• To compare cognitive control performance and brain activity between BP, MDD, and healthy controls (HCs) within a normative function framework.

Main Methods:

• Functional magnetic resonance imaging (fMRI) during a working memory task was used in 25 asymptomatic BP, 25 remitted MDD, and 25 HCs.
• A cognitive battery assessed multiple cognitive control domains, including attention, impulsivity, processing speed, executive function, and memory.
• Brain activation/deactivation patterns in HCs were correlated with cognitive performance to identify key regions for comparison between groups.

Main Results:

• BP participants exhibited significantly worse performance in impulsivity and executive function compared to both MDD and HCs.
• Both BP and MDD groups showed significantly poorer memory performance than HCs.
• Reduced deactivation in the medial prefrontal cortex (MPFC) during the working memory task was observed in both BP and MDD groups compared to HCs, and this correlated with executive function in HCs.

Conclusions:

• A shared neural feature in BP and MDD is the failure to deactivate the MPFC, a key region of the default mode network, during working memory processing.
• This MPFC dysfunction may underlie common cognitive deficits observed in both bipolar disorder and major depression.