Many of us believe that a person’s mind becomes less active as he grows older. But this is not true, according to Dr. Lissy F. Jarvik, professor of psychiatry at the University of California, Los Angeles, and a board member of the New Center for Aging at the Veterans Hospital. She has studied the mental functioning of aging persons for several years. For example, one of her studies concerns 136 pairs of identical twins, who were first examined when they were already 60 years old. As Dr. Jarvik continued the study of the twins into their 70s and 80s, their minds did not generally decline as expected