Cognitive impairment in affective psychoses: a meta-analysis

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• Cognitive impairment is considered for schizophrenia diagnosis, partly to differentiate it from bipolar disorder (BD).
• Existing evidence indicates cognitive deficits in BD persist even in euthymic states.
• Psychotic features in mood disorders may exacerbate cognitive impairment, complicating differential diagnosis.

Purpose of the Study:

• To conduct a meta-analysis examining the extent and nature of cognitive impairments in affective psychoses (AP).
• To assess if cognitive deficits can differentiate schizophrenia from BD.
• To analyze moderator variables influencing cognitive performance in AP.

Main Methods:

• Systematic literature search identifying 27 relevant studies.
• Meta-analysis and meta-regression of cognitive data from 763 patients with AP (BD and major depressive disorder) and 1823 healthy controls.
• Subgroup analyses to investigate moderator effects.

Main Results:

• Patients with AP exhibited significant impairments across all 15 assessed cognitive tasks, with large effect sizes for most.
• No significant differences in the magnitude of cognitive impairment were found between bipolar disorder and major depressive disorder groups.
• The most pronounced deficits were observed in symbol coding, Stroop task, verbal learning, and category fluency, indicating issues with attention, learning, and memory.

Conclusions:

• Cognitive impairments are a core feature of affective psychoses, affecting various domains.
• The pattern and magnitude of cognitive deficits in AP are similar between bipolar disorder and major depressive disorder, limiting their use in differential diagnosis.
• Cognitive impairments in AP are generally more pronounced than those reported in euthymic BD patients.