In examining cognitive changes in aging populations, aside from the theoretical debates, researchers have reported that cognitive processes progressively decline as chronological age advances. Studies have tended to describe the cognitive declines as gradual and general, rather than being attributable to discrete cognitive losses in specific areas of functioning.
Several studies have supported the existence of age-related cognitive decline, while other studies dispute the severity of such declines. Research interest is increasing in the areas of identifying factors related to cognitive decline and interventions to abate them. Under the direction of Ronald C. Petersen and Michael Grundman, the National Institute on Aging is studying whether daily doses of vitamin E or donepezil can prevent those with mild cognitive impairment from developing Alzheimer's disease. Other studies are investigating cholinesterase inhibitors and anti-inflammatory agents as a means of slowing the progression of mild cognitive impairment.
Psychologists who studied memory change identified diminished memory capacity in the elderly as attributable to a number of processes, such as slowed semantic access and a reduced ability to make categoricaljudgments. Other researchers concluded that older subjects were slower in mental operations but were not less accurate. Some researchers hypothesized that slower speed tied up processing functions, resulting in apparent memory impairment. Still others hypothesized that older adults have more trouble with active memory tasks because of increased competition for a share of memory processing resources, whereas others linked the aged's poor performance on working memory tasks to an actual deficiency in processing resources. Finally, some researchers concluded that older adults might simply have less mental energy to perform memory tasks. These studies accept gradual memory decline, or a slowing of processing, as a normal by-product of aging.
There are some who believe that mild cognitive impairment is a neurological disorder. This belief stems from the identification of atrophy of the left medial lobe and small medial temporal lobe, low parietal/temporal perfusion, and asymmetry of the brain as revealed by computed tomography. One study identified those with small hippocampi as prone to developing Alzheimer's disease. Additionally, electroencephalogram tracings of the brains of patients with mild cognitive impairment and patients with Alzheimer's disease showed similarities.
R. A. Hock, B. A. Futrell, and B. A. Grismer studied eighty-two elderly persons, from sixty to ninety-nine years of age, who were living independently. These normal adults were tested on a battery of eight tasks that were selected to reflect cognitive functioning, particularly measuring primary and secondary memory, memory for nonverbal material, span of attention, the capacity to divide attention among competing sources of stimulation, and two motor tasks requiring psychomotor integrity. This study found a gradual, progressive decline in cognitive functioning but found that the decline did not reach statistically significant levels. The decline was general, suggesting that it may have been a function of reduced attention rather than more discrete losses. This finding appears to be consistent with the notion that crystallized intellectual or abstract processes are well maintained across time. There were suggestions that speed of information processing is a sensitive measure of the aging process.
It is possible, however, that the tasks selected for this study did not discriminate between younger and older aging adults because the tasks may be more reliable for assessing brain injuries and psychologically impaired persons, who were not included in the population studied. Consequently, further studies on the same cognitive tasks with impaired aged adults would be necessary to see if the same relationships and conclusions would apply. Individuals with impaired cognitive functioning offer a unique opportunity to determine if the brain continues to show the same propensity to function as a unitary, global system as is observed with individuals who experience the normal aging process.
Although the brain does exhibit localization of functions, with specialization of certain brain cells for specific functions, its overall mode of operation is as a total unit. The brain has an exceptional capacity to compensate for the loss of some specific functions and continue the rest of its mental operations. This capacity or flexibility in brain function has been termed equipotentiation. Further studies of individuals with brain impairments will help to show how the brain attempts to carry out its overall functions when more specific impairments have been sustained. When cognitive disorders result in faulty information processing, actual observable changes may occur in a person's daily behavior. The previously neat person, for example, may neglect personal hygiene. The person who previously exhibited exceptional verbal abilities may speak in a socially inappropriate manner. The staid conservative businessperson may act impulsively or even make unreasonable decisions about personal finances and may show impaired social judgment.
Was this article helpful?