Abstract
The cognitive functioning of human beings declines over time. There is evidence to support that this degeneration in cognition results from the gradual breakdown of biological factors and actually starts quite early in life. By the time a person reaches late adulthood, several biological changes lead to reduced cognitive capacity that are commonly identified as signs of ageing. The decline, however, varies from person to person. While some elders face minor challenges such as poor memory and lack of focus, others can suffer from sever ailments such as depression, Alzheimer’s syndrome, and dementia. The steady decline in cognitive ability can have grave implications in terms of an ageing work force. While nations struggle to retain to large portion of elder workers to maintain a balance in the workforce, the ability of such employees to cope with fast paced technological change as well as an increasing challenging corporate environment may be limited.
It is often considered a norm for elderly citizens to be forgetful and simply not be able to understand or adapt to changes in their environment. However, it is important to understand what caused older adults to become incapable of focusing or solving problems, instead of simply dismissing these symptoms as ‘signs of ageing’. Research has revealed that, as a person grows older, the biological factors that support mental ability gradually breaks down and this process can actually begin in the mid twenties . These factors include lowered regional brain volume, cortical thinking, binding and signalling of dopamine receptor, and myelin integrity loss .
The onset of this reduced ability reveals itself in the form of basic signs of aging such as the inability to focus on tasks, being forgetful, and being unable to solve problems. In extreme cases, the elder may suffer from ailments such as severe depression, dementia, and Alzheimer’s syndrome. The rate at which cognitive ability degenerates varies from person to person based on various factors such as obesity, poor nutrition, stressful lifestyle, support and social groups, genetics and hormonal conditions, and other biological and medical conditions . However, most of these factors can be controlled leading to a reduction in the rate of degeneration.
Aging impacts the brain at various levels including macro-structural and sub-cellular. The mitochondrial and neuronal membranes deteriorate with age and these results in reduced cell bonding and weakening of the neural function. Acute reductions in the signalling and synthesis of neurotransmitters, as well as lowered synaptic plasticity and density further lessen the efficiency of the human brain as age progresses . The cortical thickness of the brain reduces at the rate of 0.5% to 1.0% annually as a result of shrinking and dying neurons. All these factors can account for 25% to 100% of the difference in cognitive functioning among young and older adults .
The efficient functioning of the brain and cognitive capacity is supported by a network of biological systems. The disruption of the synergy between these system due to factors such as insulin resistance, chronic inflammation, hormonal imbalances, and oxidative stress, can lead to the degeneration of the physical brain which in turn results in cognitive decline . The brain uses about 20% of the total oxygen consumption of the human body. Over time, oxidative stress has been known to kill neurons, even among healthy older adults, and have been linked to cognitive decline and the onset of Alzheimer’s disease .
The blood-brain-barrier formed of endolithelial cells created a wall between the brain and the general circulatory systems, thereby protecting it from infections and irritants. Chronic inflammation, caused by poor lifestyle habits such as smoking, alcohol consumption, poor diet, insufficient sleep and obesity, makes the blood-brain barrier vulnerable to the entry of irritants. Once these enter the central nervous system, the irritants reduce neurogenesis, or the process that produces fresh neurons, and can cause further damage by killing existing ones . Older adults who have a history of these habits are more likely to experience rapid cognitive decline. Imbalances in hormones such as Estrogen, Testosterone, thyroid hormones, dehydroepiandrosterone or DHEA, and Pregnenolone, can cause deregulation in the transcriptions of genes that are crucial in governing cognition . As older adults are more likely to undergo hormonal changes as a result of aging, they are more susceptible to past paced reduction in cognitive ability.
In addition to these factors, other physical and mental activities have also been found to impact cognitive decline over time. For instance, an expansive study of 33,000 participants observed over a span of 12 years found that people who lead physically active lives showed 38% lesser cognitive decline over the study period, when compared to those who did not have sufficient physical activity . Physical activity of an older adult generally decreases as age progresses as their bodies are unable to cope with physical stress. Other medical conditions such as disabilities that present themselves with the onset of old age would also limit a person’s mobility. As such, the longer an older adult stays inactive, the faster their cognitive function can be expected to decline.
There is also a substantially knowledgebase of studies centred around the relationship between brain plasticity and cognitive decline. Neural plasticity is the brains ability to adapt itself to be able to perform regular physical tasks better. For example, someone who is a beginner at typing will have a low word per minute typing speed and will mostly need to keep looking at the keyboard in order to know where the right keys are. However, through practice, the same person is able to acquire a fast typing speed and without looking at the keyboard. The same concept applies to every task a human being performs since birth.
Activities that pose a mental challenge develop the connection and synergy between neurons, thereby making the brain more efficient at performing a host of other tasks . Hence, those who are employed in mentally challenging jobs witness lesser cognitive decline when compared to those who are employed in the physical labour market. Mentally active persons are also less likely to develop Alzheimer’s disease as older adults .
The availability of information will enable better awareness of risk factors among the general public, resulting in a conscious shift in lifestyles and habits that have a negative impact on cognition. This knowledgebase will also prove to be highly beneficial for healthcare providers who will be able guide older adults, and even young adults, on how to cope with and limit cognitive decline. Research in this field, particularly those related to the biological and physical impacts on the brain, will facilitate the development of medication aimed at slowing down the pace of decline. Overall, research in cognitive decline can lead to improvements in the quality of life of older adults, lowering the possibilities of developing serious mental diseases such as Alzheimer’s and dementia.
Finally, cognitive decline has severe economic implications as well. With several nations facing the challenge of an aging workforce and retaining older employees who are nearing the age of retirement, it is crucial that older adults have the cognitive capacity to adapt and adopt fast paced technological changes and survive in a highly competitive corporate market. Good cognitive health holds the potential to extend the retirement age and allow older employees to work for more years. This will have a multi-pronged positive impact. Firstly, older employees will be able to earn for longer, thereby providing them with greater financial security post retirement. Organizations will be able to benefit from the retained knowledge and skill set of highly experienced older employees. Nations will be able to address shortages in labour arising from mass retirements. Healthcare costs arising from supporting mentally challenged elders can also be substantially reduced. All these development are greatly dependent on the research conducted into the various aspects of cognitive decline among older adults.
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