THE MYTH OF SENILITY is an important book for the concerned layman and the health care professional, especially the physician, for whom it would make an excellent text. Scholarly, with an impressive bibliography, this book is an expansion of author Robin Henig's original article in The New York Times Sunday magazine, in which she examined the neurophysiologicl and psychological efforts of wearing one's trousers rolled, an event to which we must all aspire, if we consider the alternative.

Henig, an editor of Bioscience, separates the normal effects of advancing age from disease, disuse, institutionalization, and self-fulfilling prophecy -- behavior which results from reinforcement, in which aging persons become as they are expected to become, forgetful and a little dotty.

The mind, writes Henig, "is like a muscle. It must be used and challlenged in order to function well." For most of the elderly, physical brain changes do not necessarily cause behavioral changes, but boredom, fear and depression can. In general, healthy people remain intellectually intact, perhaps forgetting where they put their glasses, but, more importantly, remembering that they wear glasses. While I learn that daily my mind is becoming smaller and wetter, a disquieting thought, author Henig assures me that the odds favor a healthy functioning old age for most Americans, which fact alone is enough to recommend the book.

The author writes with the clarity and restraint necessary in the treatment of such material, but is capable of writing with some verve and on occasion makes an interesting anology. A cell part called a lysosome, which can determine whether a neuron lives or dies, is compared to a garbage man, who "rarely comes by anymore to pick up the trash."

There may be two culprits in the problem of memory impairment with which we associate the elderly. The first may be the hippocampus which is tucked inside the cerebral cortex and thought by scientists to lose 40 percent of its cells by the time a person reaches his eighties. The second may be the fact that older brains have a greater level of background noise, neuronic impulses against which it is increasingly difficult to sort our what is material. What seems to be affected in memory is "the pact at which an indivicual can sift through his memory roster to come up with the correct bit of information on demand." The memory is still there, but just harder to grasp, like chasing after a kite that has lost its string. Aging then primarily means a slowing down of information processing, which is better news because older people can be taught how to search more effectively for stored information.

An interesting bit of information is the terminal drop hypothesis, in which it has been shown that serious illness at work in the body has an impact on cognition. The phenomenon shows up statistically as a sharp decline in test scores among persons who will die within five years.

The author distinguishes between pseudosenility, senile symptoms which are the result of physical disease, and Alzheimer's Disease, the true senility, which affects 600,000 to 1.2 million of those over 65 and another 60,000 under 65. In pseudosenility, senile symptoms result from an illness affecting some organ other than the brain. But they are most often interpreted as a natural effect of aging rather than the result of an illness. Explaining the reason these precursor symptoms are missed, the author writes, "Confusion in an elderly patient is much like suicide in Philadelphia was to the comedian W. C. Fields: redundant."

Alzheimer's disease, on the other hand, accompanied by brain lesions in the cerebral cortex and the hippocampus, may have a viral or genetic etiology making it potentially curable.

Senility cures, under the heading "Self-Help Route," such as choline, lecithin, Vitamin E, nicotnic acid, ribonucleic acid, and Gerovital H3, are examined for their effectiveness as are those the author labels "small help," and which include anti-senility drugs, high pressure oxygen, brain shunting, and interpersonal therapies.

Treatment of the aged depends on attitude. Ageism is not promulgated by the advertisement media alone, which has long taken the rap. Prejudices are also taught in medical schools, where, under an ethic of dramatic cure and rapid recovery, young medical students gain the impression during training round that old patients are "more frustrating, more incurable, more expendable than the young."

Thompson Bowles, dean at The George Washington University Medical School, is quoted as saying, "Until recently, our courses in biochemistry and other basic sciences have always presumed that human life begins at birth and ends at about age fifty." This accounts for well-meaning doctors who say to aging patients with physical symptoms, "You're no spring chicken any more," or "What do you expect?" Author Henig cites the case of an 82-year-old-woman in an ICU, recovering from a lung tumor. When the woman began to tear at her tubes, staff rushed to inject her with powerful tranquilizers, only to find out seven hours later, when they took a reading of her blood gases, that she had a serious deficiency of oxygen in the bloodstream. The test would have been automatically made on a middle-aged patient with the same symptoms.

Bringing medical school curriculums up to date is only a partial answer. We need to examine our criteria for what is useful, pragmatism being a cornerstone of our national character, and perhaps a flaw.

Kenneth Pelletier, the author of Mind as Healer, Mind as Slayer , has written another book with a holistic perspective, in which the human being is considered not just a biological organism, but a psychological and social one as well. The title Longevity: Fulfilling Our Biological Potential , tells us that Pelletier's approach to aging may well be what Browning had in mind when he wrote, what no one has ever really believed, "Grow old with me, the best is yet to be." Certainly the focus of this book, vigorously applied prevention of the effects of aging upon body and psyche, with the aim of longevity, a robust life span may well be "the last for which the first was penned."

Pelletier points out that in about 20 years or so, just about the time it takes to pay off a mortgage, almost one third of our population will be over the age of 60, making the elderly our fastest growing minority. This mandates a shifting of priorities by the providers of health care, and a change in attitude so that there may be a shift from "pathology management," caring for the already ill and diseased, to the active promotion of longevity, dramatically recasting the nation's health strategy to emphasize the prevention of disease. The author presents optimal aging not as decline, but something like a rubber band with a lock, that one, with the right combination, may stretch. Impediments to such a shift in emphasis include powerful lobbyists and the rapid growth of the "pathology management industry" which has a vested interest in the maintenance of the status quo.

The state of the art of research and theories of aging are reviewed, including cellular decline, the wearing out of tissue, genetic instruction, and the neuroendocrinological forces which determine the way an organism adapts to environmental stresses. All of these and others are in the running, with perhaps the biochemical in the lead.

Pelletier discusses the subjects of regeneration and rejuvenation, areas of inquiry which have fascinated man since medieval alchemists lopped off the legs of salamanders to watch them grow back. He presents concepts of lowered body temperatures in which it has been demonstrated that animals live longer, drugs which retard the rate of aging, and biochemical links between mind and body. He suggests that the principles of regeneration require a subtle connection between mind, matter and environment. Addressing the potential for human rejuvenation, Pelletier cites philosopher Jacob Needleman.

"A man may live quite normally . . . with only one kidney -- indeed, two thirds of each kidney may be taken without serious disturbance. One-tenth of adrenal tissue is all that is really necessary for the body, and four-fifths of thyroid substance may be removed without abnormal effects. Only one-fifth of the pancreas is needed to furnish the insulin which the organism requires, and as for the busiest and most versatile organ of the body, the liver, three-fourths of it may be lost without serious harm. Ten feet of the small intestine (normally twenty-three feet long) were taken out of one patient and in many cases almost all of the large intestine was cleared away with results that actually seem to have been beneficial. Blood sugar and calcium level, systolic pressure, lung capacity, are all greater than need be. Even great areas of the brain are expendable."

Pelletier then focuses on areas in which we may actively participate in our own behalf, giving whole chapters replete with useful data to lifestyle, including the manner in which we customarily react to stress, work satisfaction, and the ability to adapt and change; nutrition; and exercise.

The most interesting chapter of the book was the evaluation and review of studies of both centenarian communities and centenarians, in which it was found that while genetic endowment and dietary practices were influential factors, physical activity, sexual activity, environment and life satisfaction, were equally, if not more, important.

This fine book, also well documented, is not quite as easy to ready for the lay person, although anyone with a keen interest in the subject is advised to stick it out through the early chapters. The essential message and the rich information which follow are worthwhile.