Brain functional changes across the different phases of bipolar disorder

Area of Science:

• Neuroimaging
• Psychiatry
• Cognitive Neuroscience

Background:

• Functional imaging changes in bipolar disorder across illness phases are poorly understood.
• Understanding these changes is crucial for diagnosis and treatment.

Purpose of the Study:

• To compare brain activation during a working memory task in individuals with bipolar disorder across different mood states (mania, depression, euthymia) versus healthy controls.
• To investigate the neural correlates of cognitive function in bipolar disorder.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to assess brain activity during the n-back task in 38 participants with bipolar disorder in mania, 38 in depression, 38 in euthymia, and 38 healthy controls.
• Activations and de-activations were compared between groups using statistical analyses and a linear mixed-effects model.

Main Results:

• Individuals with bipolar disorder in mania and depression exhibited reduced activation in the dorsolateral prefrontal cortex and parietal cortex compared to controls.
• All bipolar disorder subgroups showed impaired de-activation in the ventromedial frontal cortex.
• Reduced activation in the left dorsolateral prefrontal cortex was more pronounced in mania than euthymia.

Conclusions:

• Bipolar disorder is associated with mood state-dependent hypoactivation in the parietal cortex.
• Reduced dorsolateral prefrontal cortex activation is characteristic of mania and depression, potentially improving during euthymia.
• Failure to deactivate the medial frontal cortex suggests trait-like abnormalities in bipolar disorder.