Disability and dementia trends under a life course perspective
In many European countries including Spain, trends of physical disability in old age show that transitions towards mobility disability occur later in life and onset of more severe disability is postponed to older ages. European studies on cognitive function in old age show that dementia risk has decreased at every age in recent decades.
Longitudinal studies of aging using a life course perspective have shown that prevention or postponement of physical disability and dementia requires to: a) reduce poverty and interpersonal violence during the life course; b) promote health behaviors since childhood to old age; c) provide healthy environment s for aging and d) health care including good quality management of chronic conditions.
There is agreement that in high income countries, severe disability has being postponed but there is scarce information for the very old age group, those beyond 85 years of age. Disability trends are generally decreasing but less so in countries where disability had been already low, such as the Netherlands and Sweden [1] where severe disability had already decreased between 1980 and 1990[1].
Historical events have shaped social and economic conditions influencing exposures to chronic disease risk factors, which in turn have changed the risk of chronic diseases throughout the life course of individuals. A life course perspective is needed to interpret disability survey results. It also allows to take into account the conditions of life of specific birth cohorts [2].
Using a life course perspective, the aim of this text is to review the current debate on population disability trends in high income countries. We propose, first, that the concepts and methods of life course epidemiology can increase our understanding of population health and disability trends in a world undergoing rapid demographic, social and economic transformation.
The concepts and methods of life course epidemiology can increase our understanding of population health and disability trends in a world undergoing rapid demographic, social and economic transformation
Second, we use the available evidence from three studies in Spain to argue that country level factors, beyond individual health factors, may underline the observed disability trends by modifying the average risk of disability in the population. Last, we examine the opportunities for dementia prevention and how mass preventive intervention can alter the magnitude of the announced epidemic of dementia.
There is real potential to change the relationship between chronological age and the incidence of chronic disease and disability by reducing exposure to poverty and violence from childhood through old age, increasing healthy behaviors across the life course, and ensuring access and coverage to good chronic disease prevention and management in old age
We conclude that there is a real potential to change the relationship between chronological age and incidence of chronic diseases and disability by reducing poverty and violence exposures from childhood to old age, increasing healthy behaviours along the life course and warranting access and coverage to good prevention and management of chronic diseases in old age.
Current disability burden.
The recently published Global Burden Disease 2013 report illustrates the challenges that increasing trends of multimorbidity and disability pose to the health systems of all countries, including high income countries[3]. We are told that population growth and population aging are the driving forces of the increases in prevalence of chronic diseases and particularly diabetes. The number of people with neurological, respiratory and musculoskeletal conditions is increasing in high income countries and particularly in Europe.
The leading cause of years lived with disability in Spain is diabetes, followed by back and neck pain, major depressive disorders, falls, hearing impairment, migraines, other musculoskeletal disorders (osteoporosis and osteomyelitis and associated fractures), chronic obstructive pulmonary disease, and anxiety
We are also warned that the first leading cause of years lived with disability in Spain is diabetes, followed by back and neck pain, major depressive disorders, falls, hearing impairment, migraines, other musculoskeletal disorders (osteoporosis and osteomyelitis and associated fractures), chronic obstructive pulmonary disease and anxiety. Main killers, cardiovascular disease and cancer, are not listed here.
Due to improved treatments, mortality is decreasing faster or increasing slower than prevalence of disease. For instance, for diabetes in Europe, age standardised prevalence rates increased by 43% globally while mortality increased only 9% in the period between 1990 and 2013. What would be the comparable figures for Spain, where diabetes has become the leading cause of years with disability? In addition, back pain and neck pain are disputing the second and third places of the list and competing with major depressive disorders. Respiratory chronic conditions, such as COPD and asthma are located in the list just prior to anxiety. Thus, the Global Burden of Disease report ranks disability causes in different European countries and emphasizes the importance of diabetes, muscular-skeletal conditions, mental health and respiratory chronic conditions. To complete the picture, hearing impairment is clearly listed as the sensory deficit responsible for more disability years.
Hearing impairment is clearly listed as the sensory deficit responsible for more disability years
Examining disability by age groups in those high income countries of the world, we are told that only 0,03% of those over 80 years of age are free of sequelae from the diseases considered in the GBD; 10% had between 1 and 4 sequelae, 64.6% had between 5 and 9 sequelae and 25.1% had 10 or more sequelae. Since prevalence of chronic conditions increases with age and the population distribution of ages shifts to older ages, there is been an increase of 52% in the number of people with 10 or more sequelae between 1990 and 2013. Women were more likely to fall in that group.
These results give a good summary of the burden of disability in Europe. We conclude that, compared with findings from previous GBD reports, we have an increasingly older population with selected chronic conditions (diabetes, musculoskeletal conditions, chronic respiratory disease, mental diseases and hearing impairment) leading to multiple sequelae and disability. More women than men are affected by multiple sources of disability and this gender difference has been attributed to sex and gender differences.
We have an increasingly ageing population with certain chronic diseases (diabetes, musculoskeletal conditions, chronic respiratory diseases, mental illness and hearing problems) that result in multiple sequelae and disability
How does a life course perspective contribute to understanding these trends?
The picture we have drawn corresponds to certain birth cohorts, who were born and have lived through the twentieth century and who have been exposed to the living conditions prevailing in Europe between the first and second world war (or the Spanish Civil War), the post-war period with the development of the Welfare State, the establishment of universal old age pensions, the improvements in health coverage through National Health Systems, the recent advance of neoliberalism, the successive economic crises of the last quarter of the twentieth century, the 2008 Great Recession and austerity measures, curtailing the Welfare State and imposed to face the last and more profound economic and social crises of 2008-2014. These experiences have shaped the health and function of the population of older adults at different stages of their life course.
Epidemiologic studies of older adults, conducted mostly in Europe and in North America, have repeatedly shown the strong effects of childhood socioeconomic status and early life social adversity on physical function and disability in old age. In addition, adulthood and old age adversity have been shown to have cumulative effects on physical function in old age[4-6].
Epidemiologic studies of older adults, conducted mostly in Europe and in North America, have repeatedly shown the strong effects of childhood socioeconomic status and early life social adversity on physical function and disability in old age
Disability trends need to take into account the strong influence of the social and economic conditions during the life course on the patterns of chronic diseases and disability in old age. In spite of this evidence, we are unaware of current disability predictive models that have integrated a life course perspective.
Disability trends in old age in Spain: three studies with different designs and some contradictory findings.
Three epidemiologic studies have analyzed the disability trends in the period around the turn of the century. We will describe them briefly and we will try to draw conclusions in spite of apparently diverging results.
The first study compares prevalence estimates of severity of disability in the basic activities of daily living (ADL) or in mobility using the Spanish National Disability, Impairments and handicap surveys of disability conducted by the National Institute of Statistics in 1986 and 1999. Findings show that age standardized ADL disability prevalence increased slightly for men (0.5%) and for women (1.8%) but age standardized mobility disability declined from 28% to 15% in men and from 37% to 25% in women. This very impressive decline in mobility disability would lead us to believe in an optimistic future. Although these figures are based on surveys and do not give us information on individual changes through time, they suggest that disability is being postponed to advanced ages and the number of years lived with disability is decreasing at the individual level[7]: the proportion of disability free life expectancy increased both in men and women over 65 years of age between 1986 and 1999.
The second study is a longitudinal study of a representative sample of older adults living in Leganes, a city in the Madrid Metropolitan Area. In the Aging in Leganes study, subjects were followed for 6 years and a clear postponement of the onset of both ADL and lower functional limitations related to mobility was observed when comparing birth cohorts. Thus, people who were 70 years old in 1993 had the same prevalence of ADL disability than those 76 years old in 1999. Since institutionalization in the Leganes population in that period was negligible, these results support a postponement of disability in successive cohorts. Postponement could be related to the improvement in the conditions of life (socioeconomic, nutrition, education, gender equality and work) of different cohorts and to the increased access and quality of health services for chronic diseases management following the 1986 legislation to establish the National Health System[8].
The third publication is based on data from Barcelona Health Surveys of 1986, 2000 and 2006. Results on the older population of this city do not show a decrease in the overall ADL disability prevalence rates in the population over 65 between 1986 and 2006 but an increase (particularly in older women) which is completely explained by population aging, that is the increase in the number of very old women[9]. Age-adjusted prevalence of disability in men went from 28% to 31% in men and from 46% to 53% in women between 1986 and 2006 and these increases were observed for almost all items in the ADL scale.
Using a life course perspective, we advance an explanation for the disagreement between the results of the Barcelona study and the previous studies based on national surveys or a local cohort. The older population of the city of Barcelona has on average better socioeconomic situations than the average of the national population or the Leganes cohort. Even if education is just one dimension of socio-economic status, education levels may be used to support this argument. In 1993, at baseline, 72.3% of men and 85.8% of women in the Leganes study sample had less than primary education. These figures are much higher than the corresponding figure for the sample in the Barcelona survey: 42.3% of men and 67.3% of women. In 1992, the distribution of Leganes older adults was very close to that of the Spanish population of similar age. While education is only one possible marker of socio-economic status, the maximum level
of education attained is strongly determined by early childhood social and economic environment. While older adults in the Leganes cohort had a rural and poor upbringing, Barcelona older adults have more varied origins. Therefore, we propose that the improvement of living conditions in Spain during the second half of the XXth century, and in particular for the Leganes study participants, would have led to the observed decline in mobility disability (and also in ADL disability, according to the Leganes cohort[8]) while for older adults living in Barcelona[9], socioeconomic changes have been less marked both at the individual as at the societal level, with little or no change in ADL disability.
Opportunities for dementia prevention and mass prevention interventions through a life course perspective.
In recent years the ability to prevent dementia has been recognized. In fact, seven modifiable factors for dementia can explain more than half of dementia cases in the world population[10,11]. This list of 7 factors is not complete since it does not include other known factors related to social networks[12] and nutrition[13]. Dementia prevention would require shifting of the population distribution of these known risk factors and would imply modification of social conditions (improving education and social participation), behavioral factors (reducing physical inactivity and smoking) or improving the clinical management of well-known chronic conditions (hypertension, diabetes, depression and obesity). Several clinical trials are ongoing in Europe and North America to assess the efficacy of modifying these factors to reduce dementia risk but our knowledge on the etiology of dementia already supports preventive population interventions from childhood to old age. Cognitive decline should be considered more as an age –related condition that can be postponed than as a disease entity susceptible of therapeutic intervention in old age[14]. Here again, the potential to change the relationship between dementia and old age rests on our ability to modify risk factors prevalence along the life course.
The list, although not complete, of the 7 factors that can prevent dementia would involve modifying social conditions (improving education and social participation), behavioral factors (reducing physical inactivity and smoking) or improving the clinical management of well-known chronic conditions (hypertension, diabetes, depression and obesity)
Conclusion
Disability trends have been observed and predicted based on current and past patterns of chronic diseases. However, the potential to change these trends lays on our ability to modify risk factors along the life course, both for physical and cognitive decline and age-related disability and dementia. Known risk factors include early child social and economic adversity, lifelong education, income and social participation, healthy behaviours and good quality management of chronic conditions in adulthood and old age. We have accumulated enough scientific knowledge to pass to action and to assert that prevention of physical disability and dementia requires a strong political will to reduce poverty and violence during the life course and to promote good health behaviors since childhood to old age, to provide healthy environments in old age and good quality health care.
References
1. Christensen, K., et al., Ageing populations: the challenges ahead. Lancet, 2009. 374(9696): p. 1196-208.
2. Kuh, D., et al., A life course approach to healthy ageing: the HALCyon programme. Public Health, 2012. 126(3): p. 193-5.
3. GBD, Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet, 2015.
4. Guralnik, J.M., et al., Childhood socioeconomic status predicts physical functioning a half century later. J Gerontol A Biol Sci Med Sci, 2006. 61(7): p. 694-701.
5. Birnie, K., et al., Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis. PLoS One, 2011. 6(1): p. e15564.
6. Sousa, A.C., et al., Lifecourse adversity and physical performance across countries among men and women aged 65-74. PLoS One, 2014. 9(8): p. e102299.
7. Sagardui-Villamor, J., et al., Trends in disability and disability-free life expectancy among elderly people in Spain: 1986-1999. J Gerontol A Biol Sci Med Sci, 2005. 60(8): p. 1028-34.
8. Zunzunegui, M.V., et al., Decreasing prevalence of disability in activities of daily living, functional limitations and poor self-rated health: a 6-year follow-up study in Spain. Aging Clin Exp Res, 2006. 18(5): p. 352-8.
9. Espelt, A., et al., Disability among older people in a southern European city in 2006: trends in gender and socioeconomic inequalities. J Womens Health (Larchmt), 2010. 19(5): p. 927-33.
10. Barnes, D.E. and K. Yaffe, The projected effect of risk factor reduction on Alzheimer's disease prevalence. Lancet Neurol, 2011. 10(9): p. 819-28.
11. Norton, S., et al., Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet Neurol, 2014. 13(8): p. 788-94.
12. Zunzunegui, M.V., et al., Social networks, social integration, and social engagement determine cognitive decline in community-dwelling Spanish older adults. J Gerontol B Psychol Sci Soc Sci, 2003. 58(2): p. S93-s100.
13. Valls-Pedret, C., et al., Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial. JAMA Intern Med, 2015. 175(7): p. 1094-103.
14. Lock, M., The Alzheimer Conundrum: Entanglements of Dementia and Aging. 2013,Princeton, New Jersey: Princeton University Press.
Pregunta
Respuestas de los expertos
Scientific knowledge on the importance of reversing the risk factors that promote situations of physical or cognitive disability is very broad. Dr. Zunzunegui's excellent work in which she reviews some research is a good example that provides scientific evidence based on studies carried out in our country.
The positions of international organisations on the subject have been constant for years. The WHO has published numerous reports on the impact of social determinants on health, defined as "the circumstances in which people are born, grow, work, live and age, including the broader set of forces and systems that influence the conditions of everyday life"(1,2,3). Furthermore, all the scientific production around the active ageing paradigm and its determinants (4) further substantiate the urgent need for public authorities in the different countries of the world to take action to change these trends.
However, it seems that population-based actions to promote and prevent health - in this case disability and physical and cognitive impairment as people age - are still not sufficiently successful in public policy.
Population-based health promotion and prevention actions are still not sufficiently successful in public policy. They require cross-cutting and also evolutionary, life-course approaches, which are rare in systems based on knowledge and highly specialised and compartmentalised intervention.
They require cross-cutting and also evolutionary, life-course perspectives, which are rare in systems based on knowledge and highly specialised and compartmentalised intervention. They also require the explicit recognition that we live in societies where social inequalities increase, especially in crisis situations.
Is it possible to reverse these trends without a cross-cutting and population-based approach to preventive actions?
In some gerontological planning (5) we have advocated actions that facilitate decision-making throughout life in order to reach old age in better conditions. "Making decisions in time" should become a motto for public authorities. In addition to upholding people's dignity and autonomy, this position is cost-effective and avoids later investments in long-term care.
But to move in this direction, we need to "recognise ourselves in the population that we are" (6). Beyond the evidence that countries such as ours have a very long-lived population, we also know that the shortcomings in our welfare system are becoming more acute every day: education, health, housing and access to employment are pillars that are faltering if we do not provide them with funds and public commitment to ensure greater equality and equity in their access by the population. Our neighbourhoods, towns and cities also need care (economic and human) to guarantee pleasant, healthy, friendly, digitally accessible environments, in which preventive actions are taken on by the entire population from childhood onwards. Taking care of ourselves is not only "going to the doctor": it is going to a decent, attractive school, equipped with austere means, but for everyone, it is preventing obesity by eating healthily, it is enjoying accessible, clean and safe parks, streets and homes, it is having a decent salary, it is enjoying culture, it is reconciling work and care so that we can dedicate the necessary time to the people we love (sons and daughters, fathers and mothers, friends...). It means being able to build community and care for its growth. It is to place ageing in all policies, to "normalise" it in order to contribute to eliminating ageism and age discrimination.
Taking care of ourselves is not only "going to the doctor": it is going to a decent, attractive school, equipped with austere means, but for everyone, it is preventing obesity by eating healthily, it is enjoying accessible, clean and safe parks, streets and homes, it is having a decent salary, it is enjoying culture, it is reconciling work and care so that we can devote the necessary time to the people we love (sons and daughters, fathers and mothers, friends...). It means being able to build community and care for its growth. It is to include ageing in all policies, to "normalise" it in order to contribute to eliminating ageism and age discrimination.
In short, a good old age is built throughout life, free of stereotypes, based on people's rights. Let's make decisions at the right time. Tomorrow is too late.
1.Final Report of the WHO Commission on Social Determinants of Health 28 August 2008. https://www.who.int/social_determinants/thecommission/finalreport/es/
2.Reducing health inequities by acting on the social determinants of health . 2009. https://apps.who.int/gb/ebwha/pdf_files/A62/A62_R14-sp.pdf?ua=1
3.World report on ageing and health. WHO 2015. https://apps.who.int/iris/bitstream/handle/10665/186471/WHO_FWC_ALC_15.01_spa.pdf?sequence=1
4.Active Ageing. A policy framework 2002. http://envejecimiento.csic.es/documentos/documentos/oms-envejecimiento-01.pdf
5.Active Ageing Strategy in the Basque Country 2015-2020. Basque Government.
Dr. Zunzunegui's question is at the heart of many deliberations on public health and health promotion. My answer here will refer to two bodies of knowledge, related to implementation science and health determinants, respectively. While both are relevant and useful, I will clearly favour the latter over the former.
In her question, Dr. Zunzunegui states that we have knowledge on how to reduce disabilities in older adults. This claim will no doubt be shared by a good number of actors involved in what is now called implementation science (Brownson et al., 2015) and its various forms, an extensive movement whose growth has intensified in the last 15 years and whose aim is to help bridge the gap between research and practice. It is argued that knowledge and tools are available, but implementation is often flawed. In response, massive research efforts have produced implementation models to guide planners and practitioners in implementing programmes and practices to achieve change. Systematic reviews and other cutting-edge syntheses of evidence-based interventions have been published in a variety of fields and jurisdictions to facilitate their dissemination and implementation. Other studies have highlighted barriers to the adoption and implementation of promising interventions by organisations with public health fiduciary mandates: insufficient funding, lack of time, lack of incentives or support from higher levels of governance.
When I think of older people, I am reminded of a public health department whose strategic planning deliberately excluded older people, on the premise that efforts aimed at children and young people would have a greater positive impact on population health. It is clear that even when knowledge and tools are available, there can still be barriers to implementing solutions to prevent, slow and treat disabilities in older populations.
A second body of knowledge emphasises social inequalities in health and their reduction as an important component of the public health agenda. Closely linked to this are the social determinants of health: "the circumstances in which people are born, grow, live, work and age, and the systems in place to cope with disease" (WHO, 2010, p. 1), i.e. the circumstances and conditions that determine people's health status and the inequalities in health outcomes.
The most powerful levers for action are public policies that act on the determinants of health and, more generally, on the economic and political structures that condition them - a Herculean task if ever there was one!
From this point of view, the most powerful levers for action are public policies that act on the determinants of health and, more generally, on the economic and political structures that condition them. A Herculean task if ever there was one! At which end do we start? Raphael (2017) suggests three courses of action. First, we must continue to "[tell] the hard facts" about the causes of health inequalities among older people. In this regard, a plethora of exemplary studies, conducted in a variety of countries, have successively confirmed that variables such as education, socioeconomic status and material conditions at different stages of life play a key role in the incidence of morbidity, disability, frailty in later life and beyond. These findings clearly support an agenda for action on social determinants. It is important to continue this research and, above all, to disseminate the results widely. "Storytelling' is the second proposed course of action. Researchers themselves and older people can certainly testify to the impact of initiatives aimed at improving their living conditions and environment. Minkler's (1985) seminal work in the Tenderloin Neighbourhood in San Francisco, California, is a good illustration of the impact of actions aimed at the living conditions of socio-economically disadvantaged older people. Finally, the third course of action is to support policy action that promotes health and human development. There is a range of useful tools for citizen action in this regard: opinion letters, messages on social networks, demonstrations, etc. However, we - researchers and health professionals - also have access to capital and resources that we should not hesitate to put at the service of the health of the older population.
In short, there are at least two possible answers to the question posed. Both are relevant and useful. The second, however, has proven to be a much more powerful lever, not only for reducing the inequalities that generate disease and injury, but also for facilitating the development and implementation of public health interventions.
Lucie Richard, PhD lucie.richard@umonteal.ca
References
Browson RC, Tabak RG, Stamatakis KA, Glanz K (2015) Implementación, diseminación y difusión de intervenciones de salud pública. En Glanz K, Rimer BK, Viswanath K (Eds.), Health Behavior: Theory, Research, and Practice (5ª ed.) (Págs. 301-325). San Fancisco, CA: Jossey-Bass.
Minkler M (1985) Construyendo lazos de apoyo y sentido de comunidad entre los ancianos del centro de la ciudad: The Tenderloin Senior Outreach Project. Educación y comportamiento para la salud, 12 (3), 303-314.
Raphael D (2017) Implicaciones de las inequidades en salud para la práctica de promoción de la salud. En Rootman I, Pederson A, Frohlich KL, Dupéré S (Eds.), Health Promotion in Canada: New Perspectives on Theory, Practice, and Research (4ª ed.) (Págs. 146-166). Toronto, ON: académicos canadienses.
Organización Mundial de la Salud (2010). Antecedentes 3: Conceptos clave. Obtenido de https://www.who.int/social_determinants/final_report/key_concepts_en.pdf
Respuestas de los usuarios