APOE and schizoaffective disorder: Additionally, drawing on animal work demonstrating that ApoE4 carriers have a chronically “leaky” BBB, Hammer and colleagues demonstrated that patients with schizoaffective disorder show a higher than expected co-occurrence of NMDAR Abs and ApoE4 carrier status compared to patients with other psychiatric diagnoses and healthy controls, suggesting that in seropositive individuals, a leaky BBB confers susceptibility toward a schizoaffective phenotype (60).