Bipolar I and bipolar II disorder: cognition and emotion processing

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• Cognitive impairment is a potential endophenotype of bipolar disorder (BP).
• Limited understanding exists regarding cognitive and emotion processing deficits in BP subgroups and their link to depression.
• Facial emotion recognition deficits are also noted in BP.

Purpose of the Study:

• To investigate the relationship between depression and cognitive/emotion processing impairments in BP.
• To compare cognitive and emotion processing across BP I and BP II subgroups.
• To determine if depression severity influences these impairments.

Main Methods:

• 36 patients (25 BP I, 11 BP II) underwent cognitive testing and a facial emotion recognition task.
• Performance was compared to published norms and controls.
• Statistical analyses included Binomial Single Proportion tests, t-tests, and Mann-Whitney tests.

Main Results:

• BP patients exhibited impairments in memory, naming, and executive functions compared to norms.
• Cognitive performance was mostly unrelated to depression ratings.
• BP patients showed impaired recognition of surprise (75% vs. 89% in controls) and anger recognition correlated with depression severity.
• BP II patients demonstrated more significant deficits in IQ, memory, and executive functions than BP I patients.
• Differences between BP subgroups were not explained by depression severity, medication, or electroconvulsive therapy (ECT).

Conclusions:

• Cognitive impairment and isolated facial emotion processing deficits are confirmed in BP patients.
• These deficits appear largely independent of depressive symptoms.
• Cognitive deficits are more pronounced in BP II patients, suggesting recurrent depressive episodes may have a greater long-term impact on cognition than manic episodes.