This process accelerates after the age of 50. Many diseases affect the CNS and sense organs. Although it gradually increases during middle age, there is a point at which a slight additional decrease in blood flow causes serious vascular impairment such as a stroke. Head injuries, sometimes caused by falls, can damage the sense organs in the inner ears, or the brain itself. The worst disability occurs when both sense organs and CNS structures are damaged simultaneously.
Physical activity is very important for recovery from injury to the sensory systems.
The general debility of aging can negatively affect recovery if it results in a decreased level of activity. Diseases of the eyes, such as glaucoma and cataracts, decrease visual sensory function and are a common problem in old age. Injuries to the knees, hips, and back often do not completely heal, leaving some limitation of motion. Arthritis can cause permanent crippling, non-reversible effects. Osteoporosis leads to bone weakness and increases the probability of serious injury from a fall, or might cause a spontaneous fracture and lead to a fall.