A、It remains as active as ever. B、It tends to be less active. C、It loses the ability to reason. D、It functions well in learning

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. Javik, professor of psychiatry at the University of California, Los Angeles.  Dr. Jarvik 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’s continued the study of the twins into their 70s and 8Os, their minds did not generally decline as was expected.
    However, there was some decline in their psychomotor speed. This means that it took them longer to accomplish mental tasks than it used to.  But when speed was not a factor, they last very little intellectual ability over the years. In general, Dr. Jarvik’s studies have shown that there is no decline in knowledge or reasoning ability. This is true not only into the 30s and 40s but also into 60s and 70s as well.
    As for learning new things, and ability to remember, studies by Dr. Jarvik and others show that the old are equal to the young. It is true that older people themselves often complain that their memory is not as good as it once was.  However, much of what we call "loss of memory" is not that at all. There usually was incomplete learning in the first place. For example, the older person perhaps had trouble hearing or poor vision, or inattention, or was trying to learn the new thing at a speed that was too fast.
    In the cases where the older person’s mind really seems to decay, it is not necessarily a sign of a decay due to old age or "senility". Often it is simply a sign of a depressed emotional state. The depression usually can be counteracted by counseling, therapy with a psychologist, or medications which fight depression.