Cognitive function in unaffected twins discordant for affective disorder

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Cognitive impairment can occur in euthymic affective disorder patients.
• Prevalence of cognitive impairment before illness onset is unclear.
• Genetic liability may influence cognitive function in affective disorders.

Purpose of the Study:

• To investigate if genetic liability to affective disorder is associated with cognitive impairment.
• To explore cognitive function in healthy individuals with a high genetic risk for affective disorders.

Main Methods:

• Cross-sectional, high-risk case-control study.
• Compared cognitive performance in 203 healthy monozygotic (MZ) and dizygotic (DZ) twins.
• Identified twins with (High-Risk) and without (Low-Risk) a co-twin history of affective disorder.

Main Results:

• Healthy twins with a co-twin history of unipolar disorder showed widespread cognitive deficits.
• Twins with a co-twin history of bipolar disorder exhibited deficits in memory and working memory.
• MZ High-Risk twins displayed more significant cognitive impairments than DZ High-Risk twins, suggesting a genetic link.

Conclusions:

• Discrete cognitive impairment is present before affective disorder onset and appears genetically transmitted.
• Cognitive function may be a candidate endophenotype for affective disorders.
• Findings support a genetic basis for cognitive deficits associated with affective disorders.