Trait and state corticostriatal dysfunction in bipolar disorder during emotional face processing.

Area of Science:

• Neuroscience
• Psychiatry
• Brain Imaging

Background:

• Bipolar disorder (BD) is associated with limbic and prefrontal cortex (PFC) abnormalities in emotional processing.
• Some abnormalities in BD are mood-state dependent, while others persist into euthymia.
• Few studies have examined neural responses across elevated, depressed, and euthymic states using emotional stimuli of varying valence.

Purpose of the Study:

• To investigate trait- and state-related neural system responses in bipolar disorder (BD).
• To assess regional brain responses to positive, negative, and neutral emotional stimuli in individuals with BD across different mood states.
• To compare neural responses between individuals with BD and healthy comparison (HC) individuals.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to scan 134 subjects (76 with BD, 58 HC).
• Participants processed faces depicting happy, fearful, and neutral expressions.
• Analyses focused on trait- and mood state-related features in BD, including individuals in elevated, depressed, and euthymic states.

Main Results:

• Decreased ventral anterior cingulate cortex (VACC), orbitofrontal cortex (OFC), and ventral striatum responses to happy and neutral faces were observed in the BD group compared to HC, independent of mood state.
• Elevated mood states were linked to reduced right rostral PFC activation to fearful and neutral faces.
• Depressed mood states were associated with increased left OFC activation to fearful faces.

Conclusions:

• Abnormal VACC, OFC, and ventral striatum responses to happy and neutral stimuli appear to be trait features of bipolar disorder (BD).
• Acute mood states in BD are associated with additional lateralized abnormalities, including diminished right rostral PFC responses in elevated states and increased left OFC responses in depressed states.