This study had 3 main purposes: (1) to examine the effect of ApoE polymorphism rs429358 on cognitive function of patients with schizophrenia and healthy controls; (2) to investigate the relationship between ApoA1 or ApoB levels and cognitive function in patients with schizophrenia; and (3) to investigate whether the relationship between ApoA1 or ApoB levels and cognitive function is regulated by the ApoE polymorphism rs429358. Here, APOB is linked to schizophrenia.