Recent studies based on the neuroimaging analysis, genomic analysis and transcriptome analysis of the postmortem brain suggest that the pathogenesis of schizophrenia is related to myelin-oligodendrocyte abnormalities. However, no serious neuropathological investigation of this protein in the schizophrenic brain has yet been performed. In this study, to confirm the change in neuropathological findings due to the pathogenesis of this disease, we observed the expression of myelin-oligodendrocyte directly in the brain tissue of schizophrenia patients.

Myelin oligodendrocyte glycoprotein (MOG) was evaluated in the cortex of the superior temporal gyrus (STG) and the hippocampus in 10 schizophrenic and nine age- and sex-matched normal control postmortem brains.

The expression of MOG was significantly lower in the middle layer of the neocortex of the STG and stratum lucidum of CA3 in the hippocampus in the long-term schizophrenic brains (patients with ≥30 years of illness duration) than in the age-matched controls. Furthermore, the thickness of MOG-positive fibre-like structures was significantly lower in both regions of the long-term schizophrenic brains than in the age-matched controls.

These findings suggest that a long duration of illness has a marked effect on the expression of MOG in these regions, and that myelin-oligodendrocyte abnormalities in these regions may be related to the progressive pathophysiology of schizophrenia.

The enlarged cava septi pellucidi (CSP = 6 mm in length) have been reported as a reliable marker of an underlying neuropsychiatric disease or disorder. Differences in the dimensions of cava longer than 6 mm associated with a neuropsychiatric impairment could be of possible clinical and forensic significance.

We obtained 479 brains from autopsied persons (310 males and 169 females, aged 22–89 years) and observed that 110 brains (75 males and 35 females) had CSP, of which the length of CSP was equal to or longer than 6 mm on 69 (49 males and 20 females) of them. These cava were classified into four groups depending on the past medical histories of the autopsied person: five without neuropsychiatric history (asymptomatic CSP), 25 schizophrenic patients, 22 alcoholics, and 17 with a past head trauma (symptomatic CSP).

The linear parameters of CSP (i.e. length, width) of the symptomatic and asymptomatic groups were measured and were statistically analyzed. Analysis revealed that the cava in the group of schizophrenic patients were significantly longer and wider.

Discriminant function analysis was used to derive a mathematical formula to classify CSP into one of the groups obtained based on width measurements of the cavum.