Aging changes in the nervous system
Information:
BACKGROUND
The nervous system is probably one of the most misunderstood in relation to normal aging. It is a common misconception that all elderly people become senile. Many times, confusion is blamed on "getting old" when it may, in fact, be caused by an illness. Although changes do occur in the nervous system, it cannot be assumed that senility is a normal part of aging.
The nervous system has two divisions. The central nervous system consists of the brain and spinal cord. It processes nerve messages. The peripheral nervous system is made up of the nerves coming to and from the spine (spinal nerves) and the nerves in the body. This portion of the nervous system carries messages to and from the central nervous system.
PHYSICAL CHANGES OF AGING
Nerve cell mass is lost. This causes atrophy of the brain and spinal cord. Brain weight may decrease significantly from the maximum "young adult" weight.
The number of nerve cells decrease, and each cell has less "branches" (dendrites). Some nerve cells lose their coating (a process called demyelinization). These changes slow the speed of message transmission. After a nerve carries a message, there is a short time when it must rest and cannot carry another message (called the latency period). Aging increases the latency period.
Waste products from atrophied nerve cells collect in the brain tissue, causing plaques and tangles (microtubules). Lipofuscin (a fatty brown pigment) also accumulates in nervous tissue.
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.
EFFECT OF PHYSICAL CHANGES
SOME slight slowing of thought, memory, and thinking seems to be a normal part of aging. There is evidence that continued, moderate PHYSICAL and MENTAL exercise is helpful in maintaining cognitive abilities.
Physical aging changes are not clearly related to decreased brain or spinal cord function. Changes in memory, thought, and other "cognitive" changes, while common in the very old, are not able to be directly traced to atrophy or other physical brain changes.
As nerves degenerate, the senses of touch, vision, hearing, and so on may be affected. Reflexes may be reduced or lost. Reflex changes increase problems with mobility and safety. Conversely, some reflexes that were present at birth and then lost through maturity (infantile reflexes such as the sucking reflex and grasp reflex) may reappear with advanced age. This may be a normal change or (more likely) may be a sign of a neurological disorder.
COMMON NERVOUS SYSTEM PROBLEMS IN THE ELDERLY
Delirium, dementia, and severe memory loss are NOT a normal, expected part of aging. They can, however, be caused by degenerative brain disorders such as Alzheimer's disease.
Illnesses unrelated to the brain can cause significant changes in thinking and behavior. For example, almost any infection can cause an older person to become severely confused.
Significant changes in memory, thought, ability to perform a task, and so on should be discussed with your health care provider, especially if these symptoms occur suddenly or along with other symptoms. A change in thinking, memory, or behavior is considered "significant" if is noticeably different from previous patterns, or if it affects lifestyle.
PREVENTION
There is some evidence that continued physical and mental activity helps to keep cognitive abilities (thinking, reasoning, and so on) sharp.
RELATED TOPICS
aging changes in organs, tissues, and cells
aging changes in the senses
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The information provided herein should not be used for diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Copyright 2000 adam.com, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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