Pathology of Brain Aging

This chapter describes the prevalent pathologic changes that are found in the brains of aged individuals. It describes some of the prevalent brain pathologies observed in aged persons’ brains. These observations help frame a discussion of their relationship with the aging process and with specific brain diseases. Genetics is one important place to seek clues as to whether the “aging” phenotype links specifically to Alzheimer’s disease (AD) pathology or to any other prevalent aging-linked brain pathology. Clinical signs and symptoms that may exist even in pre-teens include cognitive impairment, wrinkled skin, atherosclerosis, brittle bones, cataracts, and many other changes, although there is not a single progeria that can be said to definitely cause “accelerated aging”. By far the strongest risk factor for late-onset AD is the e4 variant of the apolipoprotein E (APOE) gene. The impact of the APOE e4 allele in terms of boosting brain Aß deposition is well established.