Introduction and current status

The prolongation of old age is a fact in the process of change; it is fundamentally the end result of increasing longevity, which was unimaginable only a few decades ago; even in the 1970s the hypothesis of a potential extension of the final stage of the life cycle, as it has been reached today, was rejected by some of the most expert demographers of the time. 

If of those born in Spain in 1908 only 3,750 out of every 100,000 Spaniards reached the age of 85, a century later almost 50,000, or half a full generation, survived to that age. This simple figure shows how during the last decades there has been an acceleration in the increase in the survival of populations - especially in rich countries but not only - which has continued a slow change that began at the beginning of the century and has increased the volume and characteristics of the older and more elderly population. During the 20th century, multidimensional transformations were consolidated that had begun fundamentally a century earlier, and among them there are three transitions that are the framework for increased survival after adulthood, - a demographic transition, an epidemiological transition (Omran, 1971; Olshawsky, and Ault (1986) and a health transition (Lerner, 1973; Frenk et al, 1991, Rogers and Hackenberg ,1986) the latter two included in the first, and all three closely interrelated with each other and with the social context in which they have historically developed. 

The change in the prolongation of the life cycle and its impact on the ageing of the population have extraordinary social and demographic consequences and are the final objective of this chapter in which, with a necessary brevity, we will reflect on some of the main factors involved in this process of prolonging old age, on the resulting heterogeneity of the elderly, as well as the existing difficulties for its study, given the limited availability of relevant data, especially in the most advanced ages. On the basis of these approximations, we can briefly point out some of the consequences that this historical transformation has and will have on the Spanish population. 

Of those born in Spain in 1908, only 3,750 of every 100,000 Spaniards reached the age of 85

1. Old age expansion 

Life expectancy at birth clearly accelerated from the 1930s onwards, due to the drop in infant mortality, which led to a rejuvenation of the Spanish population. Thus, between 1970 and 2012 alone, an average of 10 years of life were gained, which basically benefited the extension of the life of the elderly; a process that accelerated from the 1970s onwards, with men starting out with an average of 69 years of life and reaching 79 at the end of the period, while women started out at almost 75 and reached 85, twelve years later. Consequently, an ageing process has been taking place since then. Moreover, at present, we can state that this late survival is still being prolonged, without any historical precedent in the history of mankind, but also without any empirical evidence that this trend is going to end for the time being (Wilmoth, J.R., 1997), despite the fact that there will be periods of stabilisation or even regression in it. 

Once the Health Transition of a society is advanced, after a continuous decrease in mortality at all ages, deaths occur, increasingly concentrated around the modal age at death -unimodal in old age-, and death is increasingly delayed at higher ages, where an increasing proportion of the older population arrives. This trend has continued over the last four decades. On the other hand, this increase in longevity is recognisable through a twofold process that takes place during these same years; on the one hand, there is a tendency for deaths to be concentrated (compressed) at advanced ages, and on the other, this concentration takes place in parallel with the displacement of deaths to ever greater proportions and ever higher ages that were even considered extreme in the past, i.e. through an increase in longevity. We use the expressive image created by the demographer Kannisto (2000; 2001) to explain this double process, so that the curve representing the deaths of a mortality table seems to hit an "invisible wall" that slows it down, concentrating mortality around the modal age at death. We add that this "wall" is delimited by the available scientific-medical knowledge and the living conditions of the context at a given time¹. 

This late mortality has its origin in the Epidemiological Transition experienced, which has ended up concentrating deaths, mostly caused by chronic and degenerative diseases, at progressively older ages, once their intensity and the so-called society diseases (behaviours) have been reduced, but leaving behind the predominance of infectious and parasitic diseases that decimated the child and youth population to a greater extent. As a result of this change in pattern, the average life span of Spaniards has increased, as losses from chronic and degenerative causes of death have been reduced, and this survival has benefited proportionally more people over 65 than the rest of the population. 

It should be noted that the increase in survival has been largely due to a very notable decrease in the circulatory system (especially the cerebrovascular system in the case of Spain), together with a stabilisation and, only in recent years, a decrease in various types of tumours and diseases of the respiratory system

The increase in survival has been largely due to a very notable decrease in mortality of the circulatory system (especially cerebrovascular ones in the case of Spain), together with a stabilisation and, only in recent years, a decrease in various types of tumours and respiratory system diseases. On the other hand, we must highlight emerging diseases, whose mortality, although less intense, is growing rapidly; two groups of relevant causes in the older population present this pattern, mental diseases, as well as those of the nervous system and the senses, which should be attended to in order to prevent their extraordinary effects on activity limitations, disability and dependence at the end of life.  Finally, these five groups of causes constitute the pillars of mortality in the older population and govern the evolution and transformation of mortality in the present (Gómez Redondo, García-González and Faus Bertomeu, 2010). 

From what has been explained here so far, all this indicates the efficiency achieved by humanity in speeding up the potential duration of life, on the one hand, allowing children, young people and even the first old age to survive and an increasing number of survivors to enter old age, but this has as a consequence an "ageing of old age" which, together with the obvious advantages of these achievements, must also be taken into account, the new needs which they pose and, in addition, the lack of homogeneity between the growing populations which reach this vital stage. 

2. Heterogeneity of old age: age, sex and gender

At present, from the age of 65 onwards, we find subpopulations with very different profiles and characteristics and, consequently, with a diversity of needs and demands to cover

In traditional societies, old age could refer to a relatively homogeneous population from a demographic point of view, but nowadays, from the age of 65 onwards, we find subpopulations with very different profiles and characteristics and, consequently, with a diversity of needs and demands to be covered. Thus, the population that is leaving the economically active age presents characteristics that are very far from those of the over-85s, not to mention the over-100s, a group which, although a minority in the total population, is rapidly expanding at present and is expected to accelerate in the near future. These last two groups are the ones that will potentially present activity limitations, and to a lesser or greater extent disability and even dependency. In fact, the demands for care of these last elderly people, which are not fully covered by public administrations, are covered by family and social networks, which provide informal support in their place, and which are largely fed by those younger elderly people, that is, the first group mentioned, that of socially active elderly people, with another characteristic profile of our times, the care of "elderly for elderly people", as a consequence of the increase in longevity. 

The number of people aged over 80 has risen from 175,378 in 1908 to two and a half million today, of whom 1,600,000 

The ageing of old age is the main consequence of the above-mentioned transformations in mortality and longevity, but so is its feminization (Gómez Redondo and Boe, 2005; Canudas et al, 2008). The volume of the older population is growing, but its composition is also altering, one and the other being determined by the two basic demographic phenomena, Fertility and Mortality; the latter, which we are dealing with more closely in these pages, interacts with the former through the generations of belonging which, being born 65, 80 or 100 years earlier, are reaching old age. Thus, the population over 65 years of age, which in 1908 represented only 5.5% of the total population, with growth accelerating from 1970 onwards, is now around 17.5% women. However, the proportion represented by those over 80 is growing faster, from 0.89% to 3.94% at present, which in absolute terms means going from a population of around 175,378 octogenarians to one of two and a half million people of that age, 1,600,000 of whom are elderly women. Similarly, if the volume of the centenary population represents a small proportion of the old age, its growth rate has been increasing since the eighties, with the volume of almost 12,000 centenarians at present, and the figure was only 300 at the beginning of the period; this means that it has gone from representing 1.68 per 100,000 inhabitants to reaching the proportion of almost 25 centenarians per 100,000 Spaniards. 

If today we know that in the 1970s and then in the early 2000s, the growth of the elderly population experienced significant accelerations, this exponential increase in the number of elderly people will continue to occur with similar accelerations in the medium and long term, without ruling out the possibility that the volume of the elderly population will decrease as a result of economic crises of different kinds.  The various population estimates consider it foreseeable that a new increase will occur between the decades after 2030, when the growth rate of the sexagenarians and octogenarians will increase, as a result of the gradual entry of the baby-boom generations into old age and senescence.  In addition to this effect of past fertility, there is the process of prolonging life in old age, which we will continue to discuss below. 

Secular inequality in the face of death, which benefits women differently in societies that put them on an equal footing with men in terms of their living conditions, has feminised the population in general throughout history, and subsequently in old age, a process that has been observed universally. It is well known that women have a longer life expectancy than men at any age, and even more so in old age, but it is perhaps more evident to show the origin of the female majority that constitutes the elderly population, if we offer the data that although men had reached the modal age at death of 85 years in 2011, women had already reached and surpassed it (85.4) twenty-five years earlier, in 1985. A quarter of a century of difference in the process of postponing and concentrating deaths at the end of the life cycle makes clear the leading position represented by women in the increase in human longevity and explains the clear majority of women in the ageing population that characterises our societies. 

Recently, there have been signs of a potential trend towards increasing life expectancy to 65 years for both men and women, but this is not yet the case for all populations (Meslé, 2006); the continuation of the known trend towards divergence or the beginning of a new trend towards convergence by gender will depend on the evolution of these observed signs and their generalization. 

It is clear that there are other criteria of heterogeneity that can be considered, but we will not deal with them on this occasion, focusing exclusively here on the basic factors of differences in old age: age, which refers us to a diversity of situations in terms of objectives, activities, health, degrees of limitations, disability and levels of dependency, which change depending on whether we are talking about men or women, we also find notable differences generated by socialisation in values and roles, cultural and educational level, economic activity and informal activity. Suffice it to say that it is obvious that old age is heterogeneous, depending on the socio-economic and cultural level to which one belongs, but probably in parallel with what happens during the other stages of life: youth, childhood and adulthood. Likewise, the geographical distribution of this heterogeneity is unequal, and living conditions differ from one environment to another, rural-urban, Autonomous Communities, etc..., but it would be very difficult for us to consider here all the sources of inequality and above all, in some of them, to respond clearly to these and other questions mentioned above, because despite the relevance of the trends observed, which are well known, the information available regarding the older population and above all, the elderly population is deficient and very scarce. For this reason, we dedicate the following section to mentioning some of the main obstacles to progress in knowledge and its transfer to the public and private sectors, which if they were to be corrected would provide a solid base for adequately covering the needs that guarantee a greater quality of life in extensive old age that we have achieved in ageing societies.

3. Difficulties in the study of the elderly population. scarce and deficient data

A primary objective in the advancement of knowledge and its social implementation on the Spanish elderly population is to guarantee its comparability with other countries in our socio-cultural environment, which have been representing different models in providing a satisfactory old age and evidence-based care for the elderly for years, which have been representing different models in providing a satisfactory old age and evidence-based care for the elderly

This also requires long series of data to identify trends and changes, banishing fragmented, circumstantial, heterogeneous and scattered information. For this reason, I would like to mention at least a series of limitations that should be overcome in both the statistical and the socio-demographic data available, which could serve as a guide in the corresponding actions in the private and public spheres aimed at the older population of the present and especially of the immediate future. It is necessary to have a basis for orienting interventions based on solid planning: 

• Serious continuity of data, avoiding short and interrupted series. 
• Homogeneity (maintenance of variables over time and introduction of new ones based on research) 
• Comparability with the rest of the world (at least within the European Community) 
• Knowledge-based comprehensiveness (finishing at advanced ages). 
• Quality and review of data provided especially in very old population. 
• Linking demographic sources and making existing statistics profitable, avoiding the lack of interrelation between different official sources available (census, social security system, health surveys, etc.) 

There are many gaps in this respect which prevent progress in the transfer of knowledge on key issues of ageing, ageing, its transformations and above all its impact on the general well-being of society. We have mentioned some issues that lack data that would allow a causal study and among these limitations the following stand out in different areas: 

• Populations of nonagenarians, centenarians, semi-centenarians and supercentenarians, as exponents of extreme longevity, alluding to statistical secrecy and not being able to easily contrast the poor quality of the available data, despite detecting its existence, nor to investigate the causal factors of extreme longevity and the degree of satisfaction existing during this prolongation of life in those who achieve it. 
• Multiple causes of death (also anonymous) that make studies that link or associate the evolution of a group of causes with environmental, physiological, social or psychological factors impossible. 
• Dependence and Disability. Information that includes the institutionalised population, that which by definition concentrates the greatest proportion of potential demanders of services and support. Impossibility of contrasting errors and defects using different sources in their estimation. 
• Knowledge about formal and informal care and intergenerational networks of special relevance to the well-being of societies where up to four generations live together.

 (networks and multidirectionality of flows and care), incorporating complementary modules according to the results obtained, and through related surveys. 

This lack of information or its limitations come from different factors, which in any case have a common denominator, a relative lack of interest on the part of public administrations and official bodies in promoting this type of knowledge, and it is necessary for other bodies of a diverse nature to deal with the necessary contribution to the updating and maintenance of this data, completing it, so that the interventions to be implemented benefit society as a whole, anticipating new transformations and potential crises in the welfare of the elderly that are already taking place before us. 

In short, it is clear that the relationship between age, health and death is more than just a biological relationship in a life course. On the other hand, empirical evidence shows that the average life span of humanity changes  

The average life span of humanity changes permanently according to the social context, permanently according to the social context available.  We have the basic knowledge to plan interventions to increase the well-being of our ageing societies, but at the same time it will be necessary to obtain additional information to intervene in those key points that will make it possible, on the one hand, to minimise the impact that a long life could have on the quality of life of the generations living together with the elderly population, but above all, that these interventions will make it possible, in addition to a long old age, to achieve a dignified and satisfactory old age. 

Quoted Bibliography

Frenk, Julio. et al. (1991). “Elements for a Theory of the Health Transition”. Health Transition  Review, 1(1): 21-38. Kannisto, Väinö (2000) “Measuring the Compression of  Mortality”.Demographic Research, 3:24-52. 

Kannisto, Väinö (2001) “Mode and dispersion of the length of life”. Population, 13: 159-171. 

Gómez Redondo, Rosa. y Carl Boe, (2005). “Decomposition Analysis of Spanish Life  Expectancy at Birth: Evolution and Change in the Components by Sex and Age”.  Demographic Research, 13(20): 521-546 (en línea). http://www.demographic research.org/volumes/vol13/20/ 

Gómez Redondo, Rosa; Juan Manuel García y Aina Faus (2014). “Changes in Mortality at  Older Ages: the Case of Spain” En Anson, Jon y Marc Luy (eds), Mortality in an International  Perspective. Springer, Dordrecht, Heidelberg: 207-244. 

Meslé, France. (2006). “Recent Improvements in Life Expectancy in France: Men Are Starting  to Catch Up”, Population, 61 (4): 365-387. 

Olshansky, S. Jay. y A. Brian Ault. (1986). “The Fourth Stage of the Epidemiologic Transition:  The Age of the Delayed Degenerative Diseases”. The Milbank Quarterly, 64: 355-391. 

Omran, Abdel R. (1971). “The Epidemiologic Transition: a Theory of the Epidemiology of  Population Change”. Milbank Mem Fund Q, 49: 509-583. Rogers, Robert A. y Hackenberg  (1987). “Extending Epidemiologic Trasition Theory: A New Stage”. Social Biology, 34: 234- 243. 

Wilmoth, John R. (1997). “In Search of Limits” En Kenneth W. Wachter y Caleb E. Finch  (eds.), Between Zeus and Salomon: the biodemography of longevity, National Research  Council (Committee on Populatio n), National Academy Press, Washington DC: 38-64. 

¹An example of stages in the curbing of the trend described is well represented by the COVID 19 health crisis, which differentially affected the older population.