Progressive age-related decrease in regional cerebral blood flow in healthy subjects.

Regional cerebral blood flow (rCBF) was measured by the 133xenon inhalation technique in 103 healthy, nonhospitalized subjects of whom 44 were less than 30 years of age. Mean brain and hemispheric flows and rCBF decreased with advancing age. Moreover, a steep decline in rCBF became apparent as early as the third decade of life. Our findings suggest that the decline of rCBF is not limited to healthy elderly subjects, but is a progressive phenomenon that begins at an earlier age.