By the year 2030, one in five people will be over 65 years of age. Mental confusion and serious forgetfulness in old age can be caused by Alzheimer's disease or other conditions that cause incurable damage to the brain, but some 100 other problems can cause the same symptoms. A minor head injury, a high fever, poor nutrition, adverse drug reactions, and depression can all be treated and the confusion will be cured. Intelligence per se does not decline without reason. Most people maintain their intellect or improve as they grow older.
Most older people can lead an active, satisfying sex life.
Stopping smoking at any age not only reduces the risk of cancer and heart disease, it also leads to healthier lungs. Exercise at any age can help strengthen the heart and lungs, and lower blood pressure. See your physician before beginning a new exercise program.