Older and Wiser

""Use it or lose it,"" declares Restak (author of The Brain, on which the PBS special series was based) to readers wishing to increase their odds of living longer and healthier. The ""it"" is the brain, the organ that can play a primary role in determining the length and quality of a person's life. In explaining how the brain orchestrates the body's functions, the author, a neuropsychiatrist practicing in Washington, D.C., often dips into hard science, as when he describes the chemical actions of neurotransmitters and receptors. Grounding His discussions, grounded in facts and studies, give a reassuring solidity to the advice that's offered. An entire chapter is devoted to memory, with a firm reminder that Alzheimer's disease and other forms of dementia are abnormal conditions and not the inevitable result of living long. Restak discusses the effects that exercise (he recommends tai chi), diet and such substances as aspirin, caffeine and melatonin can have on the aging process. He examines the damaging effects of depression, loneliness, strokes and alcoholism and cites stagnation as the major cause of physical decline in old age. Included in the final chapter, ""Thirty Steps You Can Take to Enhance Your Brain in the Mature Years,"" is the exercise of balancing on one foot for as long as possible, then switching to the other foot, an activity that strengthens muscles, increases balance and flexibility and significantly reduces the likelihood of bone-breaking falls. This substantive, upbeat guide takes some of the edge off aging. (Sept.)