Aging Changes in the Nervous System

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Physical changes of aging

As people age, nerve cell mass is lost. This causes atrophy of the brain and spinal cord. Brain weight may decrease significantly from the maximum weight of young adulthood.

The number of nerve cells decreases, and each cell has fewer "branches" (dendrites). Some nerve cells lose their coating in 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 may collect in the brain tissue, causing plaques and tangles. Lipofuscin (a fatty brown pigment) may also accumulate 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, and some will have other changes.

Although certain changes are typical of specific brain disorders, the amount and type of physical changes is not always clearly related to changes in brain function. For example, plaques and tangles are associated with Alzheimer's disease, but some people with the most severe symptoms have fewer plaques and tangles than those who have mild or moderate symptoms.