Age Dependency of Changes in Cerebral Hemoglobin Oxygenation during Brain Activation: A Near-Infrared Spectroscopy Study

Open Access
Publisher Website
Google Scholar
Abstract
We used near-infrared spectroscopy (NIRS) to study noninvasively the influence of aging on changes in the local concentration of oxygenated hemoglobin ([HbO2]), reduced hemoglobin ([HbR]), and total hemoglobin ([HbT] = [HbR] + [HbO2]) during activation of brain function. Young subjects ( n = 12; age, 28 ± 4 years) performing calculation tasks showed an increase in [HbO2] [mean (arbitrary units) ± SD, 2.36 ± 1.07] and [HbT] (2.24 ± 1.13) in the frontal cortex, while [HbR] (−0.11 ± 0.48) decreased. Elderly subjects ( n = 17; age, 52 ± 10 years) showed a significantly lower mean increase ( p < 0.05) in [HbO2] and [HbT] levels (1.21 ± 1.38 and 0.72 ± 1.41, respectively). Regression analysis supports the hypothesis of an age-dependent decline in the activation-induced local increase in [HbO2] ( y = −0.241 x + 20.062; r = −0.431, p < 0.05) as well as [HbT] ( y = −0.346x + 22.496; r = −0.568, p < 0.05). We conclude that NIRS is a promising approach for studying changes in Hb oxygenation during brain activation in physiological aging.