  Human mentality develops with age and is altered in psychiatric disorders,
though their underlying mechanism is unknown. In this study, we analyzed
nanometer-scale three-dimensional structures of brain tissues of the anterior
cingulate cortex from eight schizophrenia and eight control cases. The
distribution profiles of neurite curvature of the control cases showed a trend
depending on their age, resulting in an age-correlated decrease in the standard
deviation of neurite curvature (Pearson's r = -0.80, p = 0.018). In contrast to
the control cases, the schizophrenia cases deviate upward from this
correlation, exhibiting a 60% higher neurite curvature compared with the
controls (p = 7.8 x 10^(-4)). The neurite curvature also showed a correlation
with a hallucination score (Pearson's r = 0.80, p = 1.8 x 10^(-4)), indicating
that neurite structure is relevant to brain function. We suggest that neurite
curvature plays a pivotal role in brain aging and can be used as a hallmark to
exploit a novel treatment of schizophrenia. This nano-CT paper is the result of
our decade-long analysis and is unprecedented in terms of number of cases.
