OBJECTIVE: To perform a quantitative analysis of the brain volume of elderly individuals in a population-based sample. MATERIALS AND METHODS: This was a radiological assessment and voxel-based quantitative analysis, with surface alignment, of 525 magnetic resonance imaging scans of individuals between 60 and 103 years of age who participated in the Saúde, Bem-estar e Envelhecimento (Health, Well-being, and Aging) study in the city of São Paulo, Brazil. RESULTS: We noted a median rate of reduction in total brain volume of 2.4% per decade after 60 years of age. Gray and white matter both showed volume reductions with age. The total brain volume/intracranial brain volume ratio differed between males and females. CONCLUSION: We have corroborated the findings of studies conducted in the United States and Europe. The total brain volume/intracranial brain volume ratio is higher in men, representing a potential bias for the conventional radiological assessment of atrophy, which is typically based on the evaluation of the cerebrospinal fluid spaces.

Keywords: Aging; Brain; Magnetic resonance imaging; Neuroimaging; Image interpretation, computer-assisted/methods.