Studies: Walking May Ward Off Alzheimer's CHICAGO - The health benefits of regular walking may include helping prevent mental decline and Alzheimer's disease, research in patients aged 70 and up has found, bolstering evidence that exercise needn't be strenuous to be good for you.    There's plenty of evidence that mental exercise, such as crossword puzzles and reading, may reduce Alzheimer's risks, but previous studies on brain benefits from physical exercise had conflicting results...