The Aging Brain

This issueof theArchivesis devoted to the aging brain. Neurologists have not always been interested in this subject. At the turn of the century, neurologic texts discussed 2 age-dependent disorders, Parkinson disease and stroke, but their real interest was focused on diseases of younger adults: neurosyphilis, tuberculous meningitis, multiple sclerosis, and spinocerebellar disorders. And rightly so, because in 1900, life expectancy in the United States was only 49 years. There were only 3 million people older than 65 years, compared with the 33.3 million in 1996, and only 72 000 older than 85 years, compared with the 2.2 million older than 85 years in 1996. It was not until 1931 that Critchley1first addressed the question of the aging brain from the viewpoint of an observant clinician. But these 3 classic articles aroused little interest at the time. Today, a preponderance of papers and reviews in many