The study revealed several interesting findings: (1) that the APOE E3 genotype was associated with less depressive symptoms in elderly patients with schizophrenia; (2) the APOE E3 genotype was associated with higher serum low-density lipoprotein; and, (3) that there was a negative correlation between low-density lipoprotein and depression score. Here, APOE is linked to major depressive disorder.