Changes in body systems and organs with age are highly variable and may be results of disease, which in turn may be affected by lifestyle. Most body systems generally continue to function fairly well, but the heart becomes more susceptible to disease. Reserve capacity declines. Although the brain changes with age, the changes are usually modest. They include loss or shrinkage of nerve cells and a general slowing of responses. However, the brain also seems able to grow new neurons and build new connections late in life. Visual and hearing problems may interfere with daily life but often can be corrected. Irreversible damage may result from age-related macular degeneration or glaucoma. Losses in taste and smell may lead to poor nutrition. Training
