We did not find evidence for a strong polygenic association for neurocognition as a single composite factor. This could be due to different genetic susceptibility for different sub-domains. We confirm this in our post hoc analyses where we found that two subdomains (working memory and vigilance) of neurocognition were predicted by PRS, though they did not survive correction for multiple tests. Earlier studies have found PRS associations with working memory in the healthy general population (Hatzimanolis et al., 2015). In addition, PRS has been associated not just with behavioral measures of cognition but also brain based endophenotypes such as prefrontal inefficiency (Walton et al., 2014). Working memory has been strongly associated with prefrontal function (Perlstein et al., 2001) and this offers potential causal mechanisms for further investigation. In our study we also found PRS associations with vigilance measured by the continuous performance test. Vigilance measured by the same test has been associated with schizophrenia PRS in a healthy population (Hatzimanolis et al., 2015).
