[单项选择]Researchers have established that when people are mentally engaged, biochemical changes occur in the brain that allow it to act more effectively in cognitive (认知的) areas such as attention and memory. This is true (62) of age.
People will be alert and receptive (63) they are faced with information that gets them to think about things they are interested in. And someone (64) a history of doing more (65) than less will go into old age more cognitively (66) than someone who has not had an active mind.
Many experts are so (67) of the benefits of challenging the brain (68) they are putting the theory to (69) in their own lives. "The idea is not (70) to learn to memorize enormous amounts of information," says James Fozard, associate director of an institute (71) aging. "Most of us don’t need that kind of skill. Such (72) training is of less interest than being able to (73) men