Prevalence of serum N-methyl-D-aspartate receptor autoantibodies in refractory psychosis.

N-methyl-d-aspartate receptor (NMDA-R) autoantibodies have been reported in people with acute psychosis. We hypothesised that their presence may be implicated in the aetiology of treatment-refractory psychosis. We sought to ascertain the point prevalence of NMDA-R antibody positivity in patients referred to services for treatment-refractory psychosis. We found that 3 (7.0%) of 43 individuals had low positive NMDA-R antibody titres. This suggests that NMDA-R autoantibodies are unlikely to account for a large proportion of treatment-refractory psychosis.