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Ageing Population

A population ages when increases in the proportion of older persons (that is, those aged 60 years or over) are accompanied by reductions in the proportion of children (persons under age 15) and then by declines in the proportions of persons in the working ages (15 to 59).

At the world level, the number of older persons is expected to exceed the number of children for the first time in 2047. In the more developed regions, where population ageing is far advanced, the number of children dropped below that of older persons in 1998.

Since 1950 the proportion of older persons has been rising steadily, passing from 8% in 1950 to 11% in 2007, and is expected to reach 22% in 2050. As long as old age mortality continues to decline and fertility remains low, the proportion of older persons will continue to increase.

Statistics

Global [1]

• In 2000, the population aged 60 years or over numbered 600 million, triple the number present in 1950. In 2006, the number of older persons had surpassed 700 million. By 2050, 2 billion older persons are projected to be alive, implying that their number will once again triple over a span of 50 years
• Globally the population of older persons is growing at a rate of 2.6% per year, considerably faster than the population as a whole which is increasing at 1.1% annually. At least until 2050, the older population is expected to continue growing more rapidly than the population in other age groups
• Marked differences exist between developed and developing regions in the number and proportion of older persons. In the more developed regions, over a fifth of the population is currently aged 60 years or over and by 2050, nearly a third of the population in developed countries is projected to be in that age group. In the less developed regions, older persons account today for just 8% of the population but by 2050 they are expected to account for a fifth of the population, implying that, by mid-century, the developing world is likely to reach the same stage in the process of population ageing that the developed world is already at
• The pace of population ageing is faster in developing countries than in developed countries. Consequently, developing countries will have less time to adjust to the consequences of population ageing
• The population of older persons is itself ageing. Among those aged 60 years or over, the fastest growing population is that of the oldest-old, that is, those aged 80 years or over. Their numbers are currently increasing at 3.9% per year. Today, persons aged 80 years or over account for about 1 in every 8 older persons (60 or over). By 2050, this ratio is expected to increase to approximately 2 persons aged 80 or over among every 10 older persons
• Because women live longer than men, women constitute the majority of older persons. Currently, women outnumber men by about 70 million among those aged 60 years or over. Among those aged 80 years or over, women are nearly twice as numerous as men, and among centenarians women are between four and five times as numerous as men

In sum, as a result of the transition from high to low fertility and the continuous reduction of adult mortality, the population of most countries of the world is ageing. This unprecedented demographic change, which started in the developed world in the nineteenth century and is more recent in developing countries, is already transforming many societies. The ageing process is expected to accelerate in the near future, particularly in developing countries.

UK [2]

USA [3]

Japan [4]

Global [5]

The Ageing Process

Ageing is a process which we all go through from the time we are conceived. In the early years, ageing is about growth and differentiation. We typically reach our physical and sensory peak in our early 20s. While some aspects of our mental ageing also peak at around this time (e.g. memory, speed of information processing), other mental abilities continue to develop throughout most of our adult lives (e.g. vocabulary, general knowledge, emotional control).

A hundred years ago, the average age of death in the UK was 50, and people around this age had numerous diseases and impairments. Today the average age of death in the UK is around 80, and these diseases and impairments are now rare until advanced old age.

Age-related changes in physical, sensory and mental capabilities.

Physical capabilities

Being able to perform physically at a level which ensures an independent lifestyle requires, amongst other things, adequate muscle strength and muscle power. These functional abilities are characterised by ‘reserve capacity’ in the young, but during the ageing process the functional reserve is depleted and impairments appear.

Muscle strength (e.g. hand grip, quadriceps strength) is at its peak around age 25 on average, and begins to decline quite sharply from around age 50. Hand strength is needed for lifting and as an adjunct to leg strength when rising from a low chair, getting onto a bus or out of the bath. Bassey (1997) shows that there is a steep decline in hand grip strength for men and women from age 45-54, and for those aged 75+ it is less than half of the value for young adults. However, muscular strength is rarely used without movement, so muscular power (which combines strength and speed) is required in dynamic activities such as climbing stairs, rising from a chair, getting on to a bus or out of a bath. Muscle power (e.g. the extensor power of the leg) tends to decline even more sharply than muscle strength (Allied Dunbar National Fitness Survey, 1992, 1997).

Other functional abilities required include: flexibility (loss of range in the shoulder joint is common in old age); balance (restoring equilibrium of the body mass to avoid falling after a person has tripped requires rapid powerful movements, and these decline with age) and endurance (the capability of sustaining prolonged dynamic activity decreases with age too). Ageing is also accompanied by a loss of elasticity. This affects the lungs and the way we walk; walking becomes less efficient because of the loss of rebound energy.

In general, physical strength is related to body size, so women are physically weaker than men at all ages. Women’s physical capabilities are about two-thirds those of men (Bassey, 1997). Women have weaker muscles and a poorer power-to-weight ratio.

Physical capabilities are also influenced by height and other bodily dimensions. Older people are significantly shorter than younger people, both because there is a large generational influence on height, and because, from mid adulthood onwards, we begin to lose height. The combined effect is that the average height of someone aged 65- 74 is 5cms less than the average height of someone aged 16-24, and this height difference is almost double for those aged 75+ (Health Survey for England, 2000).

In addition to the normal age-related changes in physiology, physical capabilities are influenced by the variety of health problems which increase with advancing age. One of the most common age-related health problems is arthritis which causes swelling and pain in the joints, and limited movement and weakness in the arms and hands, resulting in poor dexterity. People with arthritis find it difficult to get a firm grip or make fine, precise finger movements. Double actions such as push and twist are particularly difficult for people with poor dexterity.

(Inclusive Design, Chapter 1. Designing for older users).

Sensory capabilities

Physiological changes occur in all our sense organs as we age, reducing our sensitivity to incoming information. These changes begin in our late teens or early twenties, and although changes are inevitable, it is not inevitable that they will lead to impaired functioning. Functional impairments may be related to disorders which are associated with ageing, rather than to the normal processes of ageing.

Vision
Age-related physiological changes lead to a decline in the ability to see detail, to focus on near objects, to discriminate differences between levels of contrast, adapt to changes in brightness and manage in extremely bright light, as well as to mild impairments in colour vision and depth perception.

The principal physiological changes occur in the lens of the eye which is responsible for focusing light onto the retina and to the muscles of the eye which control the shape of the lens and the size of the pupil. The lens becomes more opaque and less elastic and also tends to discolour with age. The opacity and discolouration mean that less light enters the eye and an increase in illumination is necessary for older people to see detail. The discolouration of the lens also reduces colour vision, the effect being particularly to filter out blues and violets.

The loss of elasticity of the lens in adult life means that it is less able to focus incoming light onto the retina. This results in a change in the optimal viewing distance, which begins to lengthen from 8 cm at around age 10, to 50 cm at age 50, to 100cm at age 60 (Grandjean, 1986). By the age of 50, many people need to wear reading glasses to correct their long-sightedness.

The perception of distance and depth is also affected from around age 40, as the ability of the two eyes to converge on an object is reduced due to weakening eye muscles.

An increase in illumination can improve the ability to see detail, until a point is reached where the illumination is so great that glare begins to decrease performance. The discomfort and even disability which arises from glare is more disturbing to those over 40 than to the young. Because of the thickening and yellowing of the lens with age, and the reduction in pupil size, it takes longer for older people to become accustomed to seeing in a dark environment after coming from a light environment. The absolute sensitivity of the eye to light (the visual threshold) can be measured after individuals have been adapted
to the dark.

Timiras (1988) showed that, even when they have had ample time to adapt to the dark, 60 year olds require ten times as much light (1 unit on the log scale) as 20 year olds to detect that there is a light present, while 80 year olds require 100 times as much light (2 units on the log scale) as 20 year olds to detect that a light is present. This demonstrates how profound are the age-related deficits in light sensitivity. However, under normal conditions of illumination, twice as much light is required at age 40 as at age 20, and three times as much light at age 60.

(Inclusive Design, Chapter 1. Designing for older users).

A loss of visual acuity and contrast sensitivity makes the perception of objects in the environment more difficult. In particular, the detection of low-contrast objects can lead to unsafe ambulation. If not seen clearly, objects such as door thresholds and carpet edges can cause trips. Furnishing surfaces (e.g., chairs and toilet seats) that are not visually distinguishable also can interfere with safe transfers. And the loss of visual acuity and/or contrast sensitivity is more evident under conditions of low illumination.

(Lighthouse International, Aging & Vision Vol 15 No 1 Spring '03, Increased Risk of Falls: A Consequence of Vision Impairment).

Owlsely and her colleagues (1983) determined the contrast sensitivity functions of 91 people aged between 20 and 80. The results showed that from the age of 40, contrast sensitivity at higher spatial frequencies starts to decline until at the age of 80 it has been reduced by up to 83%.

(EveryEye, Old age vision: age related vision impairment explained).

Hearing
As people age, the ear structures deteriorate. The eardrum often thickens and the inner ear bones and other structures are affected. It often becomes increasingly difficult to maintain balance.

Hearing may decline slightly, especially that of high frequency sounds, particularly in people who have been exposed to a lot of noise when younger. This age-related hearing loss is called presbycusis.

The sharpness (acuity) of hearing may decline slightly beginning about age 50, possibly caused by changes in the auditory nerve. In addition, the brain may have a slightly decreased ability to process or translate sounds into meaningful information. Impacted ear wax is another cause of trouble hearing and is more common with increasing age.

Some hearing loss is almost inevitable. It is estimated that 30% of all people over 65 have significant hearing impairment.

(Medical Encyclopedia: Aging changes in the senses).

Touch
The sense of touch also includes awareness of vibrations and pain. The skin, muscles, tendons, joints, and internal organs have receptors that detect touch, temperature, or pain. Many studies have shown that with ageing, you may have reduced or changed sensations of pain, vibration, cold, heat, pressure and touch. It is hard to tell whether these changes are related to ageing itself or to the disorders that occur more often in the elderly.

It may be that some of the normal changes of ageing are caused by decreased blood flow to the touch receptors or to the brain and spinal cord. Regardless of the cause, many people experience changes in the touch-related sensations as they age.

Fine touch may decrease. However, some people develop an increased sensitivity to light touch because of thinner skin (especially people older than 70).

(Medical Encyclopedia: Aging changes in the senses).

Several studies have compared sensory threshold testing in young and elderly groups of healthy subjects. Kenshalo et al (1986) compared absolute thresholds to cutaneous stimulation at two sites (thenar eminence and plantar foot) in young (age range 19–31 years) and old (age range 55–84 years) subjects. The six modalities studied were tactile, vibration at 40 and 250 Hz, temperature increase and decrease and noxious heat. Older subjects were significantly less sensitive to mechanical stimuli (tactile and vibration) at both sites and elderly feet were significantly less sensitive than the young to warm stimuli. All older subjects showed deficits to one or more of the sensory modalities in at least one site.

Light touch - Tactile thresholds in the elderly are significantly increased (Thornbury, 1981; Bruce, 1980). This is thought possibly to be attributable to a decrease in the density and distribution of particular corpuscles and discs in the skin causing decreased spatial acuity (Schimrigk, 1980; Bolton, 1966; Gescheider, 1994; Stevens, 1995).

Vibration sense - Detection thresholds for several vibration intensities are higher in older subjects (Verrillo, 2002; Stevens, 1998; Goble, 1996; Gescheider, 1996, 1994; Schmidt, 1990). A study looking at 12 performance based tests of muscle strength, balance, gait, somatosensory discrimination, and reaction time showed that all these declined with increasing age and on a percentage scale, vibration threshold was the most rapidly affected by age (Sands, 1998) and is maximal after the age of 65 years (Gescheider, 1994). In non-diabetic elderly subjects loss of vibration sense is particularly pronounced but perception of light touch and pain are comparatively preserved (Thonson, 1993).

Spatial acuity of touch - The spatial acuity of skin at the fingertip deteriorates noticeably with age as assessed by two point threshold measurement (Stevens, 1992).Other tests of skin spatial acuity (for example, the ability to discriminate tactile gaps, orientation of lines, and the length of lines drawn on the skin) also deteriorate with age (about a 1% increase in threshold per annum between ages 20 to 80 years) (Stevens, 1996, 1995). Tactile acuity thresholds in the foot and finger are on average about 80% higher in the older subjects (age >65years) than in the younger subjects (age 18–28 years), but only 22% higher in the forearm.

It seems that the rate of deterioration of skin spatial acuity is slower at the proximal compared with distal sites (Stevens, 1996, 2003). Although the upper surface of the fingertip is more sensitive than the lower surface in both young and old subjects, the age related decline in tactile acuity is almost identical at both sites. The same also applies to the foot and suggests that the effect of ageing on the extremities is unlikely to be simply attributable to wear and tear on the contact surfaces of the hands and feet.

(PMJ Online, Effects of ageing on touch).

Cognitive capabilities

The ability to function independently is as much related to mental capabilities as to physical capabilities. The term cognition refers to the set of mental capabilities by which we pay attention to the world around us, interpret the information that comes in from our senses, learn and remember, solve problems and make decisions. While all of these abilities decline to some degree with advancing age, impairment may only be evident when an individual is faced with a situation that is novel, demanding or complex. Mental abilities which are based on bodies of information acquired over long periods of time (e.g. vocabulary, work related expertise, hobbies and interests) tend to remain stable with advancing age, whereas abilities which require the rapid assimilation and analysis of new information tend to decline quite sharply.

There is a marked age-related decline in the speed at which we can process information (Salthouse, 1991) which leads to difficulties with tasks where information is presented for very brief periods or rapid responses are required.

Most cognitive abilities reach their peak, on average, in our late teens and early 20s, and tend to remain relatively stable until our 50s and 60s, when declines become more apparent. The rate of decline differs between abilities and between individuals. Some abilities such as understanding word meanings, appear to go on increasing into late adulthood, while others, such as numerical ability or any ability which depends on speed of processing, show a steady decline from the mid-20s onwards. At any age, our cognitive ability is influenced by physical disorders, depression, medication, stress levels and amount of sleep, and with advancing age these factors may increase the amount of cognitive impairment. On the other hand, the effects of these factors are often reversible. The prevalence of degenerative brain disorders such as Parkinson’s disease, Alzheimer’s disease and vascular dementia also increase with advancing age.

Attention and concentration - The ageing process is associated with impairments in our ability to pay attention to the world around us. On average, our ability to sustain attention and to shift our attention between incoming sources of information decreases as we get older. But the most dramatic change in our attentional processes is in our ability to do two or more things at a time (e.g. Sit and Fisk,1999).

Language, numerical skill and spatial ability - While the basic understanding of language is relatively unaffected by ageing, it becomes harder to comprehend complex grammatical structures, particularly when they are preserved aurally or when the message is implied rather than explicit (Cohen, 1981). In addition to changes in language comprehension, there are some age-related changes in language production. Advancing age is associated with increasing word-finding difficulty, i.e. difficulty in recalling the proper names of people, places (e.g. Cohen and Faulkner, 1986) and the names of objects (e.g. the name of medications), as well as a reduction in verbal fluency (see Light and Burke,1988).

Numerical skills, such as adding and subtracting, multiplying and dividing, calculating proportions and percentages, and making estimates, all decline as we get older. Indeed, longitudinal studies of the same individuals tested over a number of years have shown that numerical abilities declined more than any other primary abilities (Schaie, 1988).

Our spatial abilities also tend to decline significantly with age. For example, visual synthesis, discriminating a figure from its background (even when colour and brightness contrast are good), and matching complex spatial patterns such as faces, all become more difficult with advancing age (e.g. Salthouse, 1992). Spatial orientation is also affected, e.g. the ability to find one’s way around a new environment by following a map. Compared to younger people, older adults tend to have more difficulty on constructional tasks such as assembling shapes, drawing objects or copying designs.

Learning and memory - Our ability to learn new skills and new information is extremely high during childhood and continues into our teens and early twenties. Thereafter, there is a gradual decline which means that middle-aged and older adults need to put more effort into learning compared with younger adults (Cohen, 1989).

There are two types of memory task with which older individuals have particular difficulty – remembering context and remembering to carry out an intended action. Impaired memory for context refers to the common observation that older adults may remember the content of information (a fact, a story, a joke) but not remember the source of the information (e.g. who told it to them, whether they saw it or heard it). An extension of this is that elderly people may not remember whether they actually saw an event taking place, or only heard a report of it. The other type of memory which shows marked age-related impairment is prospective memory i.e. remembering to carry out an action (Huppert, Johnson and Nickson, 2001).

(Inclusive Design, Chapter 1. Designing for older users).

The ageing population and ICT

 

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