Introduction
The process of aging is accompanied by many changes. Some changes are significant while others are less significant and can not be easily detected. One of the most significant changes which occur as a natural part of aging can be seen in a decrease in cognitive abilities.
These decreases are seen in the absence of any disease process which may affect the brain. These disease processes can include legions in the brain as a direct result of brain injury which may occur from the prolonged abuse of alcohol as in the case of Korsakoff’s syndrome. Barring injuries such as this, there is a decrease in cognitive abilities which is seen as a direct result of changes within the brain structure as well as adaptive compensation in the aging population. The changes occur on many levels and are evident in the changes in the levels of neurotransmitters, myelination of the individual neurons, processing speeds and performance on various tests. The changes which occur vary depending on the brain structure affected.
For example changes in the prefrontal lobe affect the performance of executive tasks. Executive tasks are tasks that involve the utility of working memory and activities such as planning and scheduling.
Main text
In order for one to examine the natural changes occurring to the brain as a direct result of aging, it is prudent that this examination begins with a close look at the changes occurring on the neuronal level and taking place at the synapses. Synaptic changes are directly related to the speed at which humans process information and thus they have significant implications on cognitive abilities. Evidence of brain changes can be seen as early as the middle age in that there is a decrease in the number of neurotransmitter binding sites, as well as a decrease in the level of neurotransmitters present in the brain synapses.
Dopamine neurotransmitters are responsible for the adjustment of movement in the basal ganglia as well as other very important systems within the brain. More specifically, the level of dopamine is directly responsible for Parkinson’s disease. Parkinson’s disease is the resultant of a significant drop in dopamine. This drop is much more significant than the drop attributed to the normal aging process, however, it does account for the fact that there is a propensity for Parkinson’s to be seen in the aging population.
In addition to the age-onset effects of Parkinson’s disease, decreased levels of dopamine and its effects on dopamine neurotransmission can be seen in higher cortical functioning. These effects are not readily evident, however, experimentation does illustrate that there are deficits that occur as a direct result of aging. Those deficits can be ameliorated by a change in lifestyle. This change in lifestyle was one that was illustrated by Kramer, Hahn, Cohen, Banich, McAuley et. al. (1999).
Kramer, Hahn, Cohen, Banich, McAuley et. al. (1999) examined executive function among older adults. They studied 124 adults between the ages of 60 and 75 years old who did not engage in regular exercise. The study subjects were randomly assigned to two exercise groups. One group was assigned to aerobic exercise in the form of walking while the other group was assigned to do anaerobic exercise—stretching and toning.
The executive functioning of the study subjects was examined before the six months of exercise and after the six months of exercise. The results of the study indicated that there was a significant difference between the scores of the two groups in that the group assigned to aerobic exercise did show an improvement in executive functioning. It was determined that executive functioning task was limited to the frontal and prefrontal cortex of the brain.
This region can be stimulated by exercise and as such, the cognitive deficits involving these regions can be affected by the level of activity. This study illustrates that a change in lifestyle can be effective in reversing some of the changes in the brain which result in the cognitive deficits of the elderly. Furthermore, there is a body of research that indicates that in order to prevent age-related cognitive deficits, it is prudent to increase brain as well as physical activity.
This can be done by older adults through the process of constant education and maintaining a level of physical activity. Essentially, older adults who return to college do experience age-related cognitive deficits to a lesser degree than their counterparts who do not attend institutions of higher learning.
In further examining the age-related decrease in dopamine receptors, one can see that this decrease appears to be a direct result of atrophy of the neurons.
As the neurons atrophy as a direct result of age, there is a loss in the number of synapses. This loss of synapses which occur as a result of the death of neurons affects many brain systems but does not affect all brain systems.
For example, the cerebellum may experience neuron loss after the age of sixty (60). This may be evident in dementia which is seen in many elderly individuals and is often indistinguishable from Alzheimer’s disease in its early stages.
Another age-related effect in the brain structures and in cognition can be seen in the slowing of response time as one age. The slowing of response time is evident both in motor response and in response to cognitive tasks. These effects are very individualized and can most accurately be depicted in the action potential achieved by the neurons within the central nervous system. The action potentials speak directly to the rate at which processing occurs within an individual. The action potential is an extremely complex entity in that it can vary within the same individual at different times. Furthermore, the motor responses of older adults are significantly slower than those of younger adults. This is not limited to motor response but can extend to some cognitive tasks as well.
This brings to task the notion of compensation. In order for older adults to accommodate their deficits, it is prudent for them to take measures.
In addition to the cognitive deficits which occur as a direct result of the atrophy and final death of some nerve cells, increased demyelination of some nerve cells has been cited as a reason for the age-related declines in mental and cognitive abilities. Myelin is the fatty covering of the axon of neurons. It facilitates the efficient conduction of neuronal impulses along the neurons in a manner such that when an action potential is reached, the impulses jump from node to node in a myelinated neuron. This form of action is called saltatory conduction and only occurs in myelinated neurons. It allows for the rapid transmission of impulses in that the impulses do not have to travel the full length of the neuron in order for results to be seen.
In the case where the previously myelinated neurons become delineated, neuronal responses are extremely slow when compared to their myelinated counterparts. In any case, the responses do not occur as a direct result of the loss of action potential. Essentially, changes in myelination occur as a natural response to aging.
Conclusion
Overall, aging is a natural process—one that cannot be prevented and one that is not always greeted with enthusiasm. It is one that dictates that there are both physical and mental changes that occur as a result of the slow degradation of an aging body. As individuals age, there are both cognitive and memory changes that occur in the central nervous system. Much of the changes can be attributed to the atrophy of some localized brain cells and their final death as well as the decreased dopamine, the neurotransmitter.
These deficits are most evident in the processing speeds as well as some other areas of cognition. The lion’s share of this represents the normal aging process, however, when dopamine levels become abnormally low, one can see the signs of Parkinson’s disease. In addition to Parkinson’s disease, there are a number of brain ailments that are predominantly present in the aging population. These ailments include dementia and Alzheimer’s disease.
Despite the prevalence of these diseases in the elderly, some measures can be taken in order to prevent the atrophy of brain cells. One such measure is aerobic exercise in the form of walking and another is to assure that the brain remains active. Essentially, it is prudent for the brain as well as the body to remain active as one age. Such activity can ameliorate the effects of aging.