Neurological System
The nervous system is a collection of nerves and specialized cells forming a spectacular network of connections which transmit signals between different parts of the body. It controls the activities of all body organs and tissues. Structurally, it is organized into two parts: the central nervous system, comprising the brain and spinal cord, and the peripheral nervous system, which connects the central nervous system to other parts of the body. 
The aging process is associated with many biological, physiological, environmental, psychological, behavioral, and physical processes. These changes often result in several complex health conditions dubbed geriatric syndromes. Most cells have a short life span and are easily regenerated and replaced by new cells in the human body. On the other hand, nerve cells are generated in vivo, have a longer life span, and are usually not replaced when they die or are destroyed. 
Several changes occur in the central nervous system. Firstly, nerve cells and supporting neuroglia are gradually lost with age. On the other hand, the remaining cells function less efficiently, and there is an increased concentration of harmful materials such as free radicals and iron in the remaining brain tissue (Knight & Nigam, 2017). Secondly, there is a decrease in brain mass leading to decreased function of affected areas such as the cerebral cortex, hippocampus, and motor cortex, manifesting as impairments in higher functions, memory loss, and gait. Thirdly, the ventricles increase in size and due to the loss of cells lining the ventricles. Fourthly, there is a decrease in cerebral blood flow and diminished integrity of the blood-brain barrier over time. There is also a decline in the production of neurotransmitters. Lastly, age-related changes to the vertebrae and intervertebral discs may increase pressure on the spinal cord and its branching nerve roots. This can slow down nerve impulses’ conduction along motor neurons, contributing to reduced muscular strength (Manini et al., 2013).
There is a slowed nerve conduction in the peripheral nervous system attributed to decreased axonal length, loss of mitochondria, and degeneration of peripheral neurons’ myelin sheath. This may result in decreased sensation, slower reflexes, and clumsiness. On top of that, damaged neurons are not repaired efficiently in older adults, and some are not repaired at all. 
The decrease in brain function with aging may impair mental function seen in neurodegenerative conditions such as delirium and dementia. Delirium is defined as an acute confusional state characterized by an acute decline in attention-focus, perception, cognition, and consciousness. In contrast, dementia is an acquired global impairment of intellect, memory, and personality but without impaired consciousness. 
The two conditions are similar in that they exhibit similarities in their presentation: impaired memory and judgment, confusion, disorientation, and variable degrees of paranoia and hallucinations (Fong et al., 2015). However, they also have some differences. Delirium usually has an acute onset, fluctuating course lasting days to weeks can occur at any age but is more common in the elderly with underlying conditions. On the contrary, dementia has an insidious onset, has a chronic course lasting months to years, and is more common in the elderly. Delirium is essentially due to reversible impairment of cerebral oxidative metabolism, while dementia is caused by exogenous insult or an intrinsic process affecting cerebral neurochemistry. The causes of delirium include metabolic disorders, toxins, infections, anatomic disorders, withdrawal, trauma, hypoxia, deficiencies, endocrinopathies, heavy metals, and acute vascular events (Inouye et al., 2014). On the other hand, dementia results from neurodegeneration, vascular defects, toxins, infections, autoimmune disorders, neurometabolic disorders, and other endocrinopathies.
References
Knight, J., & Nigam, Y. (2017). Anatomy and physiology of ageing 5: the nervous system. Nursing times, 113(6), 55-58.
Inouye, S. K., Westendorp, R. G., & Saczynski, J. S. (2014). Delirium in elderly people. The Lancet, 383(9920), 911-922.
Manini, T. M., Hong, S. L., & Clark, B. C. (2013). Aging and muscle: a neuron’s perspective. Current opinion in clinical nutrition and metabolic care, 16(1).
Fong, T. G., Davis, D., Growdon, M. E., Albuquerque, A., & Inouye, S. K. (2015). The interface between delirium and dementia in elderly adults. The Lancet Neurology, 14(8), 823-832

REPLY 2

Neurological SystemAs human beings age, the cerebral and the nervous system experience natural modifications as they begin to decline. The cerebral framework and the spinal cord get deprived of nerve cells along with their mass, known as atrophy (Xu et al., 2017). The nervous cells begin to convey messages slower than before. Byproducts can accumulate in the cerebrum tissue as the nerve cells disintegrate. This breaking down can cause strange alterations in the cerebrum known as tangles and plaques to begin to develop.The malfunctioning of the nerves may influence an individual’s senses. A fatty brown colored shade termed lipofuscin may likewise form in the nerve tissue. The patient may lose or have diminished reflexes or reduced sensation. This reduction in sensation and reflexes triggers problems with locomotion and an individual’s health. The slowing down of thinking, memory, and thought is a usual phase of aging. These advances are not identical for every human being.Some individuals have numerous adjustments in their nervous and cerebral tissue, other individuals have minimal to no changes. These advances are not ordinarily recognized with the influences on an individual’s capability to think. At the age of 30, an individual’s neurons decrease in quantity, the size and number of neurological cells increase, axons and dendrites start thinning and declining in quantity (Xu et al., 2017). The deviations that transpire in the central nervous system during the aging process are a reduction of the inflow of blood to the brain and a decrease in the brain’s size and weight.As one continues to age, some peripheral neurons depict shrinking of axonal extent, degeneration of myelin sheaths, and mitochondria reduction. The harm may begin due to an increase in the concentration of pro-inflammatory influences in the human body. The maturing body turns out to be less compelling in clearing harmful metabolites, and as the peripheral nerves are hardly managed, this inefficiency can add to peripheral nerve injury. The reduction of myelin eases back the conduction of peripheral nerve driving forces. In healthy patients, this decrease in conductivity leads to a few issues, but in high-risk patients such as those with diabetes, it might intensify to diabetic neuropathy (Wong et al., 2018). Harmed peripheral nerves are not fixed as easily in more seasoned individuals as in their more youthful years. A portion of these nerves are never fixed, and the damage can lead to decreased motor control and sensation.Delirium refers to an abrupt modification in the brain that leads to emotional disturbance and mental confusion. Delirium makes it challenging to remember, pay attention, think, and sleep. Although the cause of delirium is not exact, it is commonly caused by infections, organ failure, or medications. Dementia, on the other hand, is a loss of memory, problem-solving capabilities, language, and other thinking capabilities that are serious enough to disrupt one’s daily life (Livingston et al., 2020). Dementia occurs as a result of loss or damage of nerve cells and the links with the brain. Both dementia and delirium get attributed to confusion, hallucinations, impaired memory, and disorientation. The difference between the two is that delirium is a result of drug toxicity or acute illness and is usually reversible. Moreover, dementia is caused by anatomical changes in the brain and is usually irreversible.
ReferencesLivingston, G., Huntley, J., Sommerlad, A., Ames, D., Ballard, C., Banerjee, S., Brayne, C., Burns, A., Cohen-Mansfield, J., Cooper, C., Costafreda, S. G., Dias, A., Fox, N., Gitlin, L. N., Howard, R., Kales, H. C., Kivimäki, M., Larson, E. B., Ogunniyi, A., €¦ Mukadam, N. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396(10248), 413€“446. https://doi.org/10.1016/s0140-6736(20)30367-6.  (Links to an external site.)Wong, J. C., Walsh, K., Hayden, D., & Eichler, F. S. (2018). Natural history of neurological abnormalities in cerebrotendinous xanthomatosis. Journal of Inherited Metabolic Disease, 41(4), 647€“656. https://doi.org/10.1007/s10545-018-0152-9.  (Links to an external site.)Xu, X., Wang, B., Ren, C., Hu, J., Greenberg, D. A., Chen, T., Xie, L., & Jin, K. (2017). Age-related Impairment of Vascular Structure and Functions. Aging and Disease, 8(5), 590.
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