To grow older physically is often referred to pejoratively as ‘going downhill’. Because the body organs perform less efficiently physical performance deteriorates. Mental performance, however, is not so directly linked to aging. For instance, when one looks at the age at which athletes give their top performance it turns out that this is usually before their thirties; but for academics the most productive phase for turning out scientific publications is around their forties. Moreover, many academics are capable of remaining at the top of their field for a much longer period of time. For other activities such as administrative and political work people with a certain knowledge of life are usually preferred to those who are not able to boast of such experience.
Even physical limitations do not have to impede mental performance. This is shown by the fact that Franklin Delano Roosevelt (1882-1945), in spite of being disabled by polio, was elected four times in a row for the presidency of the United States. The nervous system governs mental activity. Deterioration in the functioning of the nervous system and the loss of nervestart almost directly after growth has come to a halt at the end of adolescence. It is frequently believed that a deterioration in memory is merely the result of a reduction in the number of brain . However, this assumption falsely implies that the quantity of information that may be stored in the brain is limited. In fact our memory capacity is much larger than we will ever use. It is true though, that as we grow older, the process of remembering will slow down. Sometimes it may seem as if the capacity to learn new things involves a greater effort. Young people are indeed much better able to learn a large number of words by heart within a short time. However, when the subjects for tuition are linked to the experiences and interests of a person who has left school a long time ago, and when the information is offered at intervals, the results turn out to exceed expectations.
The best precautions to take to remain mentally active well into old age are to build up new interests and to participate in and contribute to the changing world. Such an attitude also helps in coping with the changes that will be brought along by, for instance, an approaching retirement.