Brain volume changes on longitudinal magnetic resonance imaging in normal older people

Background and Purpose. The purpose of this study is to investigate the lon gitudinal age-related changes in human brain volume using stereological met hods. Methods. Sixty-six older participants (34 men, 32 women, age [mean SD ] 78.9 +/- 3.3 years, range 74-87 years) with normal baseline and follow-up examinations underwent 2 MRIs (magnetic resonance imaging) of the brain on average 4.4 years apart. The volumes of the cerebrum (defined as cortex, b asal ganglia, thalamus, and white matter), lateral ventricles, and cerebell um were estimated on the 2 MRIs using an unbiased stereological method (Cav alieri principle). Results. The annual decrease (mean SD) of the cerebral v olume was 2.1% +/- 1.6% (P < .001). The average volume of the lateral ventr icles on the second MRI was increased by 5.6% +/- 3.6% per year (P < .001). The average volume of the cerebellum on the second MRI was decreased by 1. 2% +/- 2.2% per year (P < .001). Even though the average cerebral volume wa s significantly different between men and women on initial MRI and second M RI, the percentage change of the age-related cerebral volume decrease in ma le and female brains between initial MRI and second MRI were identical. Con clusions. The findings showed that there was age-related atrophy of cerebru m and cerebellum and age-related disproportional enlargement of lateral ven tricles in normal older men and women.