Age-Related Changes in the Nervous System
The nervous system changes that occur with age do not interfere too much with day-to-day routines. Personality changes occur only if there are specific neu-rologic diseases. With age, there is a steady loss of neurons in the brain and spinal cord. Because the neurons do not reproduce, they are replaced by sup- porting cells. There is a reduction in synaptic connec-tions and neurotransmitter synthesis and secretion. Combined, this results in diminished reflexes and slower reaction time. The learning ability may be less, with some failing of short-term memory and integra-tion of sensory input. However, thinking and cogni-tion are intact.
One important change that occurs is in relation to proprioception. Balance in an individual is main-tained by the integration of input from vision, vestibu-lar apparatus, joint position sense, touch-pressure sensations, and hearing. If incorrect or insufficient in-put is received and if the input is not well synthesized, dizziness, light-headedness, and falls may occur.
Some studies have shown that the threshold is in-creased for sensations such as pain, touch, and vi-bration.
There is a general decrease in vision in most individ-uals older than age 55, requiring glasses for reading or distance. The elasticity of the lens decreases, mak-ing it difficult for it to bulge when near objects are to be seen. The protein in the lens gets altered, making the lens less transparent. Color discrimination di-minishes with age, especially differentiating greens and blues. This is probably a result of problems re-lated to filtering these wavelengths through the yel-lowed opaque lens.
There is a gradual, progressive loss of hearing for high frequency tones and the ability to discriminate spoken words.
Atrophy of neurons may result in diminished sense of taste and smell.
Changes in muscle and gland response to the auto-nomic nervous system have a profound effect on au-tonomic reflexes such as baroreceptor reflexes and vascular changes in accordance to environmental temperature. Therefore, the incidence of hypothermia and hyperthermia are higher in older individuals.
Patience is required because reflexes and movements are slow. The sight and hearing of the person should also be considered and communication altered ac-cordingly. Use of hot and cold packs should be done with care as temperature regulation is impaired. The therapist should watch for orthostatic hypotension when changing the client’s position.