brain, spinal cord, and nerve disorders
Effects of Aging on the Nervous System
 Spinal Cord 
As people age, the disks between the back bones (vertebrae) become hard and brittle, and parts of the vertebrae may overgrow. As a result, the disks lose some of their capacity to cushion, so more pressure is put on the spinal cord and on the branches of the nerves that emerge from it ( Cranial nerves and spinal nerves ). The increased pressure may injure nerve fibers at the point where they leave the spinal cord. Such injury can result in decreased sensation and sometimes decreased strength and balance. 