This portion of the nervous system carries messages to and from the central nervous system. This causes atrophy of the brain and spinal cord. These changes slow the speed of message transmission. Aging increases the latency period. These changes are not consistent in everyone.
Some people have many physical changes in their nerves and brain tissue, others have few.
Some will have atrophy AND plaques, some will have plaques and tangles, some will have other changes. Although certain changes are typical of specific brain disorders, the amount and type of physical changes are not necessarily related to changes in brain function. Physical aging changes are not clearly related to decreased brain or spinal cord function. As nerves degenerate, the senses of touch, vision, hearing, and so on may be affected. Reflexes may be reduced or lost.