ABSTRACT
The strong relationship that exists between cellular metabolic capacity and regional blood flow leads to the conclusion that a clear understanding of age-related changes in the regulation of blood flow is essential for understanding the progressive decline in cellular metabolic activity and eventually tissue function with age. In principle, microvascular density in each region of the brain could be genetically programmed. Several pharmacological agents promote microvascular growth and plasticity in the adult brain. Cerebrovascular aging can be viewed from several perspectives, including alterations in vascular density, vascular plasticity, and vascular reactivity. Rarefaction of arterioles and changes in vessel shape and structure most likely contribute to reduced flow although the possibility of capillary rarefaction and the regulation of capillary density with age remains an area for additional research. The metabolic impact of reduced blood flow may be exacerbated by altered transport across the capillary wall.
