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Physiology of ageing and problems of ageing

In document APPENDIX IV (Page 57-60)

2.1 Hypertension .1 Epidemiology

2.2.4 Physiology of ageing and problems of ageing

A number of physiologic variables decline with increasing age and thus compromise the individual’s ability to respond to pathologic insults. These variables include:

A change in vision which often is the first undeniable sign of aging. Visual function deteriorates from refractive errors and senile cataract. The elderly also have decreased visual acuity, visual fields and dark adaptation.

Ageing produces changes in the peripheral and central nervous systems that affect the neurologic structures that govern the mood, intellectual processing, skilled movement, and the perceptions mediated by special senses. These changes cause poor coordination, slowed reflexes and decline in performance of all components of basic activities of daily living.38 Over time, there is progressive cognitive decline which can advance to dementia with loss of cognitive functions including memory, thinking, orientation, comprehension, calculation, learning capacity, language, and judgement.38 The most common type of dementia is Alzheimer’s disease, followed by vascular dementia.

There is reduced hearing of high-pitched sounds as ageing progresses, referred to as age-associated hearing loss (presbyacusis). Hearing impairment causes a sensory deprivation in the elderly and may predispose them to depression, cognitive impairment and injuries. In conjunction with visual impairment, they compromise independence, necessitating a need for a care-provider.

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There is decline in olfactory and taste bud function. The elderly also suffer metabolic derangements easily after a variety of insults such as diarrhoea and febrile illness, manifesting with dehydration, due to impaired ability to retain sodium and concentrate urine. This is further worsened by their decreased thirst response.

In the respiratory system, the lung and chest wall compliance decrease with advancing age. The decrease in vital capacity of the lungs and bronchiolar ciliary movement increases collapsibility of alveoli and terminal conducting airways, thus increasing the risk of pneumonia, pulmonary emboli and atelectasis in elderly.38

In the cardiovascular system, there is reduction in elasticity of the large and medium sized vessels as well as arterial wall stiffness with ageing. Cardiac output falls also by 3% per decade as a result of reduced stroke volume and ventricular contractility. This results in raised systemic vascular resistance and hypertension which in turn may lead to left ventricular strain and left ventricular hypertrophy.38

In the musculoskeletal system, there is thinning of the cartilage that lines the joints partly because of the wear and tear of years of movement. Damage to the cartilage due to lifelong use of joints or repeated injury often compromises mobility of the joint with increased incidence of osteoarthritis. Progressive reduction in elasticity of ligaments and tendons, increase joint stiffness and reduces flexibility thereby increasing gait and balance disorder.36 Bone mineral density reduces after age 40 years significantly from osteoporosis especially in postmenopausal woman. The mostly affected bones are the end of femur at the hip, the ends of radius and ulna at the wrist and the vertebrae bone.38 Osteoporosis in elderly also predisposes to increase incidence of pathologic fracture. Changes in vertebrae at the top of the spine cause the head to tip forward, compressing the throat. As a result swallowing is more difficult, and choking is more likely. The

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vertebrae become less dense and the cushion of tissue between them lose fluid and become thinner, making the spine shorter. Thus older people become shorter. The cartilage that lines the joints tends to thin partly because of the wear and tear of years of movement. The surfaces of a joint may not slide over each other as well as they used to, and the joint may be slightly more susceptible to injury. Damage to the cartilage due to lifelong use of joints or repeated injury often leads to osteoarthritis, which is one of the most common disorders of later life. Also dehydration of inter-vertebral discs and joint cartilage with wear and tear compromises mobility of the joint with increased incidence of osteoarthritis. Ligaments, which bind joints together, and tendons, which bind muscle to bone, tend to become less elastic, making joints feel tight or stiff.

These tissues also weaken. Thus most people become less flexible. The incidence of gait and balance disorders is also increased among the elderly.102 Also, muscles cannot contract as quickly because more fast-contracting muscle fibres are lost than slow-contracting muscle fibres.

However, ageing’s effects reduce muscle mass and strength by no more than about 10 to 15%

during an adult’s life time.38

Concerning immune function, there is reduced capacity to adapt to stress with increased vulnerability to disease and probability of death.38

There is also a decline in the endocrine function, which in women causes loss of oestrogen and progesterone that makes the reproductive tract mucosa atrophy and become more subject to low-grade infections either of which can make coitus painful. Men are also supposed to become less sexually active with “Andropause”.38

In Canada, Lam et al. reported osteoarthritis as the most common medical problem followed by hypertension, osteoporosis, and depression or anxiety.103

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A study on prevalence of self-reported non communicable disease among elderly population in South Africa reported diabetes mellitus, arthritis, chronic lung infection, asthma and hypertension as common morbidities.98

Adebusoye et al. in 2011 in Ibadan reported hypertension as the commonest morbidity followed by cataract and osteoarthritis (mean morbidities was 3).5

Udoh et al. in 2014 reported cardiovascular and bone/joint diseases as the commonest non-communicable diseases in elderly patients attending tertiary health centre in Uyo South-south Nigeria.104

In document APPENDIX IV (Page 57-60)