Does performance on the standard antisaccade task meet the co-familiality criterion for an endophenotype?

Area of Science:

• Neuroscience
• Psychiatry
• Behavioral Genetics

Background:

• The "co-familiality" criterion defines an endophenotype, requiring unaffected relatives to show altered performance and heritability compared to controls.
• The antisaccade task is a candidate endophenotype for schizophrenia, but its suitability requires rigorous evaluation.

Purpose of the Study:

• To assess if antisaccade task performance measures meet the co-familiality criterion for schizophrenia endophenotypes.
• To investigate shifts in mean performance, increased variance, and heritability in relatives of schizophrenia patients.

Main Methods:

• Examined three antisaccade performance measures: reflexive saccade errors, correct antisaccade latency, and gain.
• Analyzed effect sizes, variance ratios, and heterogeneity in performance between relatives and controls.
• Assessed heritability of antisaccade performance, particularly error rate.

Main Results:

• Modest mean effect sizes were observed for error rate (0.34), latency (0.33), and gain (0.54), with significant heterogeneity.
• Error rate showed a significant increase in variance in relatives, but confidence intervals were broad.
• Latency and gain variance ratios did not differ between relatives and controls; error rate performance was moderately heritable.

Conclusions:

• Antisaccade task measures do not consistently meet the co-familiality criteria for schizophrenia endophenotypes due to inconsistent mean shifts and heterogeneity.
• While intra-familial resemblance in antisaccade performance has genetic components, it may not be directly related to a schizophrenia genotype.
• Further research is needed to definitively establish antisaccade task performance as a schizophrenia endophenotype.