Across the world people are living longer. For the first time in history, there will soon be more adults aged over sixty-five years of age, compared to children aged five and younger. The science of ageing is called gerontology and when applied to oral health, this is called gerodontology. In these disciplines, adults over sixty-five years of age are often described as ‘older people’, whilst those over eighty-years of age are called the ‘oldest-old’.
“Between 2015 and 2050, the proportion of the world's population over 60 years will nearly double from 12% to 22%.” WHO 2018.
The average life expectancy in the United Kingdom has increased from seventy years of age to eighty years of age in the past sixty years. In developing countries, these changes are becoming very pronounced, with increases in life expectancy happening over much shorter timeframes than before.
Figure 1: Percentage of world population over 65. Reproduced from UN world population prospect 2008.
In Wales, the average age of the population is expected to increase by 2.5 years over the next twenty years. This will lead to 30% of the population being over sixty-five years of age, our definition of ‘older people’.
Gerontologists call this group of people over sixty-five years of age the ‘ageing population’. Ageing populations across the United Kingdom and Wales are characterised by falling birth rates and rising life expectancy.
When we study changes in population groups, we often use age-gender pyramids. These graphs describe the relative proportion of the different age groups in any given population, with the left of the graph denoting changes in female numbers and the right, changes in male numbers for each age group. The shape of this pyramid has changed dramatically as a result of the ageing population. Whilst we used to describe the shape of the graph as a pyramid, back in the 1950s, we have seen this change to a ‘population bell’ in 2015 and now this graph is projected to look like a ‘population barrel’ by 2050. This is because of the increasing numbers of older people: the ageing population
Figure 2: Age-gender pyramids for the Welsh population. Reproduced from the National Assembly for Wales. Source, mid-year population estimates, Office for National Statistics.
As many heath conditions are associated with ageing, it is important that health care systems are aligned with this changing need. In oral health, this is becoming a pressing public health issue and will change how we provide services and target our oral health programmes in the future.
CHRONOLOGICAL Vs. BIOLOGICAL AGEING
Why is it that one seventy-year-old person can appear healthy and independent, whilst another can appear increasingly frail and become dependent for most of their activities of daily living in many areas of their life? This question captures the difference between chronological and biological ageing.
A person’s chronological age is simply a count of the number of years, months or days since their birth. In contrast, their biological age, to put it simply, the age they appear.
This separation between someone’s age, and the age that they appear to be, makes common sense and there is wide variation in the population. However, biological ageing is difficult to predict and classify as it is the result of several factors including, chronological age, genetics, socio-demographic factors like poverty, their lifestyle, nutrition and on-going disease processes.
It is this difference between these descriptions of ageing that makes defining ‘an older person’ very difficult, in reality, to do. As a result, most gerontologists simply use people’s chronological age as a ‘catch-all’.