There may be another possible explanation of the association observed in our study in the light of the vascular-inflammatory theory of schizophrenia [35]. This theory is based on observations that inflammatory vascular disease of the brain leads to psychosis and exhibits a fluctuating course as seen in schizophrenia, and that disturbances of central nervous system blood flow have repeatedly been observed in people with schizophrenia [35]. Interestingly, it has been demonstrated that the human cerebrovascular smooth muscle cells (HCSMC) isolated from cortical vessels derived from postmortem brains can express mRNAs for complement C1QB gene. As HCSMC are closely associated with amyloid beta deposits in vessels in the brain, their production of complement proteins could amplify the proinflammatory effects of amyloid in the perivascular environment, further compromising brain vascular integrity [36].