Normal Brain Aging and its Risk Factors –Analysis of Brain MRI Database of Healthy Japanese Subjects

We collected brain MRIs of 2,000 healthy Japanese and constructed an MRI database together with their characteristics such as age, sex, blood pressure, present and past disease history and cognitive functions. Volumetric analysis revealed that gray matter volume linearly decreased with time, while white matter volume remained unchanged during aging. Based on the regression line for gray matter loss, we defined a standard brain for each age group and sex. Correlation analyses using voxel-based morphometry (VBM) between gray matter volume and risk factors revealed that there were negative correlations between gray matter volume and hypertension, lifetime alcohol intake, obesity (BMI), mental status (subthreshold depression). Longitudinal study with 8 years interval revealed that there are sex difference in speed and pattern of gray matter loss with age. To clarify clinical significance of ischemic changes in the white matter, we developed an algorism for automatic detection of the ischemic changes. Using this system, we made probabilistic map of the lesion for age of 40, 50, .60 and 70. The lesion map revealed that ischemic lesion localized mainly around the ventricle and total lesion volume increased with increasing of age.