The "normal pathophysiology" of aging.

The contemporary goal of geriatrics is to limit the degeneration and deterioration of structure and function that threatens older individuals. This article suggests a different possibility. Since some structural and physiological changes generally occur, maintaining function surely is an important goal. For example, in the central nervous system, decreased central and peripheral innervation, and hypothalamic changes, require adapted responses to sensory input, proprioception, and temperature control. But some of the structural and behavioral changes of later life actually alter function for the better. These same changes bring about reduced excitability and a capacity to focus on the basics. Coupled with greater experience, these provide a realistic context for the sage judgment and true leadership that our society needs, and which may incline society to adjust to older citizens rather than simply vice versa. The tension and drama of our subject is inherent in the title. How can the same process, growing older, be both normal and pathological? This exemplifies what might be the majority opinion: that growing older has expected, normal changes, and they amount to a deterioration of function, a wearing out which is not good, and therefore is a form of pathology. But this opinion assumes that we know the true or proper function of man, and further, that it never changes. Ostensibly that would be the flower of young manhood and womanhood; any departure from that physiological state would then be downhill. Yet this depends upon one's point of view and is far from certain. The individual best suited to storm a beach or perform a ballet might not be the best one to manage a campaign or do the choreography. Again, if one is interested in flowers, then the blossom forming a seed may seem to be a pathological process. Unless, of course, one is interested in more flowers. Flowers passing to seed are the basis of evolution. What follows is a review of the changes attendant upon aging. The reader is invited to suspend judgment concerning the pathological nature of this process, concentrating only on the changes themselves and the possible adaptations they represent and require. It is possible that man and society are reciprocally evolving so that more and more of this process can be realistically seen as good, as development rather than deterioration, as advantageous for the individual in society and for society itself, promoting further, like-oriented evolution for both. Chronic conditions are cumulative. This tautology is useful for us, since it brings together gerontology, investigating the physiological consequences of aging, with geriatrics, the humane science of treating medical conditions in the elderly. There is a spectrum of probability stretching from the relatively certain physiological changes that accompany age to the always episodic appearance of truly pathological conditions that affect older people. However, since the more common of these do affect large segments of the older population, they, like gerontological changes, are pivotal in the sophisticated planning of environments for the later years. THE EYE Over 40% of our brains are devoted to visual processing (Brodal, 1981). The physics of light is reliable enough, in our earthly environment, at least to give us an accurate and relevant assessment of our surroundings. Our retinas could just as well be sensitive in the radio or ultraviolet ranges of the electromagnetic spectrum, but we've evolved to see what we see, and naturally, to construct homes, buildings, and cities that are visible to us. For persons with deteriorating vision, this spells decreasing data quality and "bandwidth" regarding their environments (Corso, 1982; Milne, 1985). What are those reductions; how do they affect people's lives? How can we use this information to improve and enrich their lives? Three geriatric conditions are fundamentally responsible for impaired vision in the elderly: macular degeneration (27%), cataract (22%), and glaucoma (12%) (Wainapel, 1994). …