Capillaries, Old Age and Alzheimer’s Disease

Abstract

Many of the minor complaints of old age may have a common etiology and are grouped together here under the term ‘the lesser ailments of aging’ (LAA). This essay proposes that they are due in large part to an age-linked reduced microcirculation. Capillary density (CD) in the tissues is determined by levels of angiogenic growth factors (AGFs). Over 47 studies have reported a reduced CD and/or waning AGFs throughout the bodies of aging animals and people. More convincing than such a generalization are the 80 sets of data comparing these two parameters in adult vs. the aged. These data have led to a hypothesis whose corollary proposes a specific treatment for the LAA. While genetically controlled, the waning levels of AGFs theoretically could be countered by pro-angiogenesis therapy and thus might ease the LAA or delay their onset. Therapies mentioned here include recombinant AGFs and inhibitors of type 5 phosphodiesterases, such a tadalafil/Cialis. Finally, Alzheimer’s disease (AD) is generally an illness of the elderly and may have a single or multiple causes. However, its clinical course may be influenced secondarily by conditions affecting the LAA. Therefore, any effective treatment of them may influence favorably the clinical course of AD.