Cohort differences in disease and disability in the young-old: findings from the MRC Cognitive Function and Ageing Study (MRC-CFAS)

Subjective Functional Difficulties and Subjective Cognitive Decline in Older-Age Adults: Moderation by Age Cohorts and Mediation by Mentally Unhealthy Days

Background and Objectives: Despite the expected positive association between subjective functional difficulties (SFD) and subjective cognitive decline (SCD), their mediation by mentally unhealthy days (MUDs) is under-studied. Moreover, few SCD studies have examined affective reactivity to functional difficulties by age cohort. This study examined the mediation effect of MUDs on the association between SFD and SCD by age cohorts' moderation among older adults. Methods: Using a cross-sectional design approach, we used the 2019 BRFSS dataset on 13,377 older adults aged 65 to ≥80 (44% males and 56% females). Results: The bias-corrected percentile bootstrap with 5000 samplings revealed that MUDs partially mediate the relationship between SFD and SCD (14.12% mediation effect), controlling depressive symptoms, education, income levels, and race. Age cohorts moderated the relationship between SFD and SCD and between SFD and SCD but not between MUDs and SCD. The predictive effects of the path from SFD to MUDs and from MUDs to SCD were stronger in the younger-old (65-69) than the middle-old (70-79) and oldest-old (≥80) age cohorts. Worse SCD was associated with being Asian, in female older adults, and in those with lower education and income levels. Conclusions: These findings extend the chronic stress theory predictions that accentuated emotional vulnerability to subjective functional difficulties may magnify SCD, particularly in the younger-old age group. By implication, preventive SCD interventions should seek to support younger-old adults in their activities of daily life for successful aging transitioning into older-age cohorts.

Secular trends in functional abilities, health and psychological well-being among community-dwelling 75- to 95-year-old cohorts over three decades in Helsinki, Finland

Background: Life expectancy has increased markedly in the past decades. Thus, it is of great importance to understand how people are ageing and if the trajectories of health and disability are changing over time. This study aimed to examine trends in functional abilities and health in independent cohorts of people aged 75–95 over three decades. Methods: This Helsinki Ageing Study consists of repeated cross-sectional postal surveys examining independent cohorts of old people (75, 80, 85 and 90+ years old). This study combined data from four waves (1989, 1999, 2009 and 2019). Results: In the most recent wave, there was an increase in the portion of participants who were able to walk outdoors easily (75-year-olds p=0.03, 80-year-olds p=0.002, 85-year-olds p<0.001; p for linearity for the study year effect, all adjusted for sex). Fewer people in the youngest age group (75-year-olds) needed daily help from another person in 2019 compared to the earlier waves (p=0.02 for linearity for the study year). Over the past three decades, the proportions of self-reported good mobility have risen 8.7% (95% confidence interval (CI) 2.3–15.1) in 75-year-olds, 11.7% (95% CI 3.9–19.6) in 80-year-olds and 20.1% (95% CI 10.7–29.4) in 85-year-olds, after adjusting for sex. Furthermore, in 2019, more people rated their health as good and scored better in psychological well-being than in the previous waves among 75-, 80- and 85-year-olds. However, no improvements were found among 90+-year-olds in any of these variables. Conclusions: People between 75 and 85 years old are presently feeling and functioning better than their predecessors. This may be an important objective for both economics and health policy.

Age Takes Hold of Us by Surprise: Conceptualizing Vulnerabilities in Aging as the Timing of Adverse Events

OBJECTIVES

Aging in the public eye can be distilled to a limited number of adverse events, such as loss of health, partnership and wealth. While these events are a constitutive part of "normal aging," they do not occur uniformly at the same time point in the life course. This study investigates to what extent bereavement, functional health loss, and onset of poverty are adequate markers of aging, and illustrates inequalities in their timing according to cohort, gender, class, education, and ethnicity.

METHODS

The English Longitudinal Study of Ageing (ELSA), collected over seven waves (2002-2016) (n = 7,890) is examined in an event history framework. Cox proportional hazard models are used with the Andersen Gill extension in case of multiple failures per respondent.

RESULTS

Persistent associations of lower occupational class, lower education, and having a black or minority ethnic background are found with increased hazards of functional health loss and wealth loss. Earlier born cohorts have lower hazards for functional health loss, wealth loss, and bereavement. Women have higher hazards for bereavement, and lower hazards for wealth loss.

DISCUSSION

The timing of adverse events is a crucial gateway through which existing social inequalities are transferred into unequal aging pathways.

Are Advances in Survival Among the Oldest Old Seen Across the Spectrum of Health and Functioning?

BACKGROUND

Mortality rates have been reduced by half over the last 60 years for nonagenarians, and the progress is continuing. The greater survival might be due to overtreatment of severely physically and cognitively disabled individuals, which is a big concern for societies and individuals.

METHODS

The study population comprised two Danish birth cohorts: the 1905 Cohort and the 1915 Cohort. At age 95, all from the two cohorts who were still alive and living in Denmark were invited to participate in a health survey that used the same assessment instrument. A total of 2,670 (56.8%) persons participated in the two surveys and survival was assessed through a 7.3-year follow-up period during which 2,497 (93.5%) had died, and with virtually no loss to follow-up.

RESULTS

Despite the increasing chance of surviving to age 95, the 1915 Cohort had significantly better health and functioning than the 1905 Cohort. The survival advantage in the 1915 Cohort continued in the follow-up period after age 95: Median survival length was 2.4 months longer, p = .011. This advantage was not statistically associated with different levels of activities of daily living, physical performance, cognitive functioning, self-rated health and life satisfaction. However, the advantage tended to be more pronounced among people with better health.

CONCLUSIONS

Life span and health increases among the oldest old. The improvement in survival for 95-year olds born in 1915 compared with 1905 was seen across the whole spectrum of health and functioning, with a tendency towards bigger improvement among those in good health.

The Increasing Importance of Friendship in Late Life: Understanding the Role of Sociohistorical Context in Social Development

Historically, family ties have been understood as the primary source of support for aging adults, and past empirical and theoretical work has highlighted the tendency of older adults to focus on close family. However, in line with demographic changes and historical increases in the diversity of social structures, friendships are increasing in importance in recent generations of older adults. Given the powerful role of context in shaping these changes, this paper offers a conceptual analysis linking individual agency to sociohistorical context as a way to understand this increasing diversity of social ties. More specifically, we propose that the individual invests time and energy to form and maintain social ties, and that each individual has a specific social opportunity structure (all potential ties that are available to invest in, as well as the costs of those investments). Furthermore, this investment of time and energy is determined in part by individual differences in capacities and motivations. We argue that sociohistorical context influences this process in three important ways: (1) in its effect on the social opportunity structure; (2) in its direct effect on time and energy; and (3) in its effect on individuals' capacities and motivations. We believe that these mechanisms can account for the increasing diversity of social ties across adulthood, as well as the potential for future historical changes.

A Longitudinal Study of Allostatic Load in Later Life: The Role of Sex, Birth Cohorts, and Risk Accumulation

Are challenging life courses associated with more wear and tear on the biological level? This study investigates this question from a life-course perspective by examining the influence of life-course risk accumulation on allostatic load (AL), considering the role of sex and birth cohorts. Using biomarker data collected over three waves (2004, 2008, and 2012) of the English Longitudinal Study of Ageing ( N = 3,824) in a growth curve framework, AL trajectories over a period of 8 years are investigated. Our results illustrate that AL increases substantially in later life. Men have higher AL than women, but increases are similar for both sexes. Older cohorts have both higher levels and a steeper increase of AL over time. Higher risk accumulation over the life course goes hand in hand with higher AL levels and steeper trajectories, contributing to the body of evidence on cumulative (dis)advantage processes in later life.

Temporal Trends in the Level and Decline of Cognition and Disability in an Elderly Population: The PAQUID Study

In line with declining trends in dementia incidence, we compared the cognitive and functional evolution of 2 "generations" of elderly individuals aged 78-88 years, who were included 10 years apart in the French Personnes Agées Quid cohort (n = 612 in 1991-1992 and n = 628 in 2001-2002) and followed-up for 12 years with assessments of cognition and disability. The impact of specific risk factors on this evolution was evaluated. Differences between the generations in baseline levels and decline over time were estimated using a joint model to account for differential attrition. Compared with the first generation, the second generation had higher performances at baseline on 4 cognitive tests (from P < 0.005). Differences in global cognition, verbal fluency, and processing speed, but not in working memory, were mostly explained by improvement in educational level. The second generation also exhibited less cognitive decline in verbal fluency and working memory. Progression of disability was less over the follow-up period for the second generation than for the first. The cognitive state of this elderly population improved, partially due to improvements in educational level.

A comparison of health expectancies over two decades in England: results of the Cognitive Function and Ageing Study I and II

BACKGROUND

Whether rises in life expectancy are increases in good-quality years is of profound importance worldwide, with population ageing. We investigate how various health expectancies have changed in England between 1991 and 2011, with identical study design and methods in each decade.

METHODS

Baseline data from the Cognitive Function and Ageing Studies in populations aged 65 years or older in three geographically defined centres in England (Cambridgeshire, Newcastle, and Nottingham) provided prevalence estimates for three health measures: self-perceived health (defined as excellent-good, fair, or poor); cognitive impairment (defined as moderate-severe, mild, or none, as assessed by Mini-Mental State Examination score); and disability in activities of daily living (defined as none, mild, or moderate-severe). Health expectancies for the three regions combined were calculated by the Sullivan method, which applies the age-specific and sex-specific prevalence of the health measure to a standard life table for the same period.

FINDINGS

Between 1991 and 2011, gains in life expectancy at age 65 years (4·5 years for men and 3·6 years for women) were accompanied by equivalent gains in years free of any cognitive impairment (4·2 years [95% CI 4·2-4·3] for men and 4·4 years [4·3-4·5] for women) and decreased years with mild or moderate-severe cognitive impairment. Gains were also identified in years in excellent or good self-perceived health (3·8 years [95% CI 3·5-4·1] for men and 3·1 years [2·7-3·4] for women). Gains in disability-free years were much smaller than those in excellent-good self-perceived health or those free from cognitive impairment, especially for women (0·5 years [0·2-0·9] compared with 2·6 years [2·3-2·9] for men), mostly because of increased mild disability.

INTERPRETATION

During the past two decades in England, we report an absolute compression (ie, reduction) of cognitive impairment, a relative compression of self-perceived health (ie, proportion of life spent healthy is increasing), and dynamic equilibrium of disability (ie, less severe disability is increasing but more severe disability is not). Reasons for these patterns are unknown but might include increasing obesity during previous decades. Our findings have wide-ranging implications for health services and for extension of working life.

FUNDING

UK Medical Research Council.

Cardiovascular risk profile and use of statins at the age of 70 years: a comparison of two Finnish birth cohorts born 20 years apart

OBJECTIVE

to compare cardiovascular morbidity and risk factor profiles of two 70-year-old cohorts of Finns examined in 1991 and 2011 and to describe prevalence of statin use according to cardiovascular risk in the later cohort.

METHODS

1920-born cohort of community-dwelling 70-year-old persons (n = 1032) participated in comprehensive health surveys, physical and laboratory examinations in the Turku Elderly Study (TUVA) during 1991-92. In 2011, identical examination pattern was performed, in a 1940-born cohort of 70-year-old persons (n = 956) from the same area. Prevalence of cardiovascular diseases (CVD) and risk factors in the two cohorts was compared. Further, each cohort was divided into three cardiovascular risk groups (high, moderate and low) based on their estimated risk. Prevalence of statin use was calculated among each risk group in the 1940 cohort.

RESULTS

coronary heart disease (25 versus 11%) and peripheral artery disease (9 versus 2%) were more common in the 1920 than 1940 cohort, respectively. Lipid profile was worse and blood pressure higher in the earlier cohort, whereas use of statins and antihypertensives was more common in the later cohort. Forty-two per cent of the 1920 cohort and 29% of the 1940 cohort were estimated to have high cardiovascular risk. In the 1940 cohort, a total of 36% used statins. Statin use was most common among high-risk persons.

CONCLUSIONS

seventy-year olds examined in 2011 had less CVD morbidity than their counterparts 20 years earlier, and their cardiovascular risk factors were better controlled which is reflected in higher use of preventive medications, such as statins and antihypertensives.

Population Aging at Cross-Roads: Diverging Secular Trends in Average Cognitive Functioning and Physical Health in the Older Population of Germany

This paper uses individual-level data from the German Socio-Economic Panel to model trends in population health in terms of cognition, physical fitness, and mental health between 2006 and 2012. The focus is on the population aged 50–90. We use a repeated population-based cross-sectional design. As outcome measures, we use SF-12 measures of physical and mental health and the Symbol-Digit Test (SDT) that captures cognitive processing speed. In line with previous research we find a highly significant Flynn effect on cognition; i.e., SDT scores are higher among those who were tested more recently (at the same age). This result holds for men and women, all age groups, and across all levels of education. While we observe a secular improvement in terms of cognitive functioning, at the same time, average physical and mental health has declined. The decline in average physical health is shown to be stronger for men than for women and found to be strongest for low-educated, young-old men aged 50–64: the decline over the 6-year interval in average physical health is estimated to amount to about 0.37 SD, whereas average fluid cognition improved by about 0.29 SD. This pattern of results at the population-level (trends in average population health) stands in interesting contrast to the positive association of physical health and cognitive functioning at the individual-level. The findings underscore the multi-dimensionality of health and the aging process.

Prevalence of acute diseases in the elderly assisted in emergency department of orthopedics

OBJECTIVE

To make an analysis of the care of elderly in an Emergency Department of Orthopedics with the primary objective to know the percentage of elderly treated, their conditions of origin and level of accidental conditions, and examine possible comorbidities, evolution and mortality rate.

METHODS

Retrospective observational epidemiological study based on survey records of a tertiary hospital during one year (January to December 2006).

RESULTS

In the year 2006 (January to December) 12,916 calls to patients older than 60 were performed.

CONCLUSION

Massive attendance of the elderly population was observed, however, the vast majority related to chronic problems that do not require urgent attention. Patients requiring urgent attention suffer from trauma related to falls and are between the seventh and ninth decades of life, mostly female and requiring hospitalization for longer periods. Level of Evidence VI, Cases Series.

Mandatory aged care insurance: a case for Australia

This paper assesses the feasibility and welfare-improving potential of an insurance market for aged care expenses in Australia. As in many other countries, demographic dynamics coupled with an upward trend in costs of personal care result in consumer co-contributions imposing a risk of expenses that could constitute a significant proportion of lifetime savings, in spite of the presence of a government-run aged care scheme. We explore issues around the development of an insurance market in this particular setting, considering adverse selection, moral hazard, timing of purchase, transaction costs and correlation of risks, as well as such contextual factors as longevity and aged care cost determinants. The analysis indicates aged care insurance is both feasible and welfare-enhancing, thus providing a gainful alternative to the aged care reform proposed by the Productivity Commission in 2011. However, while the insurance market would benefit the ageing Australian population, it is unlikely to emerge spontaneously because of the problem of myopic individual perceptions of long-term goals. Consequently, we recommend regulatory action to trigger the market development.

Cognitive and physical functions as determinants of delayed age at onset and progression of disability

BACKGROUND

This study examined the association of cognitive and physical functions with age-related transition and progression of activities of daily living (ADL) disability in a population-based longitudinal cohort of nondisabled older adults.

METHODS

A longitudinal population-based cohort study of 5,317 initially nondisabled older adults with an average age of 73.6 years of an urban Chicago community were interviewed annually for up to 8 years from 2000 through 2008. Cognitive function was assessed using a standardized global cognitive score and physical function using a combination of measured walk, tandem stand, and chair stand. A novel two-part model was used to access the relationship between cognitive and physical functions and age at onset and progression of ADL disability.

RESULTS

The sample consisted of 5,317 participants, 65% blacks, and 61% females. Twenty-five percent reported an onset of ADL disability during follow-up. After adjusting for confounders, lower cognitive and physical functions were associated with an increased risk for lower age at onset. Lower cognitive function was longitudinally associated with increased rate of progression of disability after onset. However, lower physical function did not alter the rate of progression of ADL disability.

CONCLUSIONS

Cognitive and physical functions were associated with age at onset. However, only cognitive function was associated with the rate of progression of ADL disability.

Birth cohort differences in cardiovascular risk factors in a Brazilian population of older elderly: the Bambuí Cohort Study of Aging (1997 and 2008)

The aim of this study was to investigate whether cohort differences exist in the prevalence of cardiovascular risk factors among older elderly from the Bambuí Cohort Study of Aging. Participants were those aged 71-81 years at two points in time a decade apart: 457 in 1997 (earlier cohort) and 553 in 2008 (recent cohort). The prevalence of hypertension (PR = 1.27; 95%CI: 1.19-1.36) and of diabetes mellitus (PR = 1.39; 95%CI: 1.06-1.83) was higher in the recent cohort compared to the earlier one, regardless of sex. The recent cohort had a lower prevalence of smoking (PR = 0.58; 95%CI: 0.42-0.80), and lower total cholesterol/HDL cholesterol ratio level (PR = 0.85; 95%CI: 0.80-0.89). There was a 136% increase in the pharmacologic treatment of diabetes and a 56% increase in pharmacologic management of hypertension in 2008 in comparison with 1997. Overall, the number of cardiovascular risk factors in the recent cohort remained similar to that of the early cohort.

The disabling effect of diseases: a study on trends in diseases, activity limitations, and their interrelationships

OBJECTIVES

Data from the Netherlands indicate a recent increase in prevalence of chronic diseases and a stable prevalence of disability, suggesting that diseases have become less disabling. We studied the association between chronic diseases and activity limitations in the Netherlands from 1990 to 2008.

METHODS

Five surveys among noninstitutionalized persons aged 55 to 84 years (n = 54,847) obtained self-reported data on chronic diseases (diabetes, heart disease, peripheral arterial disease, stroke, lung disease, joint disease, back problems, and cancer) and activity limitations (Organisation for Economic Co-operation and Development [OECD] long-term disability questionnaire or 36-item Short Form Health Survey [SF-36]).

RESULTS

Prevalence rates of chronic diseases increased over time, whereas prevalence rates of activity limitations were stable (OECD) or slightly decreased (SF-36). Associations between chronic diseases and activity limitations were also stable (OECD) or slightly decreased (SF-36). Surveys varied widely with regard to disease and limitation prevalence rates and the associations between them.

CONCLUSIONS

The hypothesis that diseases became less disabling from 1990 to 2008 was only supported by results based on activity limitation data as assessed with the SF-36. Further research on how diseases and disability are associated over time is needed.

Measuring disability in patients with chronic fatigue syndrome: reliability and validity of the Work and Social Adjustment Scale

BACKGROUND

Disability is a defining feature of chronic conditions, and it is an increasingly used measure of therapy effectiveness. The Work and Social Adjustment Scale (WSAS) is a simple and clear measure of disability. Although the scale is widely used, no study has yet investigated its psychometric properties in patients with chronic fatigue syndrome (CFS).

METHODS

Data from two samples of patients were used, one from a multicenter randomized controlled clinical trial of treatments for CFS (n =639) and the other from a clinic that specializes in CFS (n=384). All patients completed the WSAS as well as other measures.

RESULTS

Internal consistency and the Spearman-Brown split-half coefficient values indicated that the scale is reliable. CFS patients who had comorbid diagnoses of depression, anxiety or fibromyalgia had higher WSAS scores. High levels of disability were associated with high number of physical symptoms, severe fatigue, depression, anxiety, poor sleep quality and poor physical fitness, with correlation coefficients ranging between 0.41 and 0.11. Lower scores on the WSAS were modestly associated with better physical functioning as well as higher levels of physical capacity as assessed by a walking test. Sensitivity to change was evaluated in a subgroup of patients who had undergone a course of cognitive behavioral therapy. Disability significantly decreased after therapy and remained stable at follow-ups.

CONCLUSION

The WSAS is a reliable and valid assessment tool for disability in patients with CFS.

Trends in activity limitations: the Dutch older population between 1990 and 2007

BACKGROUND

It is not clear whether recent increases in life expectancy are accompanied by a concurrent postponement of activity limitations. The objective of this study was to give best estimates of the trend in the prevalence of activity limitations among the non-institutionalized population aged 55-84 years over the period 1990-2007 in The Netherlands.

METHODS

We examined self-reports on 12 measures of moderate or severe activity limitations in stair climbing, walking and getting dressed as assessed by OECD long-term disability questionnaire or Short Form-36 (SF-36) items, using original data from five population-based cross-sectional and longitudinal surveys (n = 54,847 respondents). To account for heterogeneity between surveys, we used meta-analyses to study time trends.

RESULTS

Time trends of 10 out of the 12 activity limitation variables studied were stable. The prevalence of at least moderate activity limitations in stair climbing [odds ratio (OR) = 1.03)] and getting dressed (OR = 1.04) based on OECD items increased over the study period. Age- and gender-stratified time trend analyses showed consistent patterns.

CONCLUSIONS

No declines were observed in the prevalence of activity limitations in the Dutch older population over the period 1990-2007. The increase in life expectancy in this period is accompanied by a stable prevalence of most activity limitations.

Prevalence and correlates of physical disability and functional limitation among community dwelling older people in rural Malaysia, a middle income country

Background

The prevalence and correlates of physical disability and functional limitation among older people have been studied in many developed countries but not in a middle income country such as Malaysia. The present study investigated the epidemiology of physical disability and functional limitation among older people in Malaysia and compares findings to other countries.

Methods

A population-based cross sectional study was conducted in Alor Gajah, Malacca. Seven hundred and sixty five older people aged 60 years and above underwent tests of functional limitation (Tinetti Performance Oriented Mobility Assessment Tool). Data were also collected for self reported activities of daily living (ADL) using the Barthel Index (ten items). To compare prevalence with other studies, ADL disability was also defined using six basic ADL's (eating, bathing, dressing, transferring, toileting and walking) and five basic ADL's (eating, bathing, dressing, transferring and toileting).

Results

Ten, six and five basic ADL disability was reported by 24.7% (95% CI 21.6-27.9), 14.4% (95% CI 11.9-17.2) and 10.6% (95% CI 8.5-13.1), respectively. Functional limitation was found in 19.5% (95% CI 16.8-22.5) of participants. Variables independently associated with 10 item ADL disability physical disability, were advanced age (≥ 75 years: prevalence ratio (PR) 7.9; 95% CI 4.8-12.9), presence of diabetes (PR 1.8; 95% CI 1.4-2.3), stroke (PR 1.5; 95% CI 1.1-2.2), depressive symptomology (PR 1.3; 95% CI 1.1-1.8) and visual impairment (blind: PR 2.0; 95% CI 1.1-3.6). Advancing age (≥ 75 years: PR 3.0; 95% CI 1.7-5.2) being female (PR 2.7; 95% CI 1.2-6.1), presence of arthritis (PR 1.6; 95% CI 1.2-2.1) and depressive symptomology (PR 2.0; 95% CI 1.5-2.7) were significantly associated with functional limitation.

Conclusions

The prevalence of physical disability and functional limitation among older Malaysians appears to be much higher than in developed countries but is comparable to developing countries. Associations with socio-demographic and other health related variables were consistent with other studies.

Trends in disability prevalence over 10 years in older people living in Gloucestershire

INTRODUCTION

life expectancy in the UK appears to be growing faster than healthy life expectancy, which may imply that there are increasing years of disability. There are few sequential studies examining changes in disability amongst older people within a defined locality.

METHODS

the population aged 75 and over of 10 general practices in Gloucestershire was surveyed using a validated postal questionnaire for disability called the Elderly At Risk Rating Scale. Surveys were carried out in 1998 and 2008. Age-adjusted disability prevalences were measured. Care home residents were under-represented in the 1998 survey, and missing data was supplied from a countywide census of care home residents in 2000.

RESULTS

response rates of 81 and 74% were achieved. Reductions in disability prevalence were found for mobility, vision and self-care, but there was no significant change in a measure of self-rated health. Higher rates of independence were found in both genders and across the age range in 2008. The improvements suggested that the latter sample was equivalent to subjects being 3.8 years 'younger' than 10 years before and entering dependency on care 2.1 years later.

DISCUSSION

the prevalence of disability affecting activities of daily living appears to have reduced over 10 years in older people in Gloucestershire. If generalisable, these results provide some optimism for current trends in ageing in England.

Ageing populations: the challenges ahead

If the pace of increase in life expectancy in developed countries over the past two centuries continues through the 21st century, most babies born since 2000 in France, Germany, Italy, the UK, the USA, Canada, Japan, and other countries with long life expectancies will celebrate their 100th birthdays. Although trends differ between countries, populations of nearly all such countries are ageing as a result of low fertility, low immigration, and long lives. A key question is: are increases in life expectancy accompanied by a concurrent postponement of functional limitations and disability? The answer is still open, but research suggests that ageing processes are modifiable and that people are living longer without severe disability. This finding, together with technological and medical development and redistribution of work, will be important for our chances to meet the challenges of ageing populations.

What is self-rated health and why does it predict mortality? Towards a unified conceptual model

The association of self-rated health with mortality is well established but poorly understood. This paper provides new insights into self-rated health that help integrate information from different disciplines, both social and biological, into one unified conceptual framework. It proposes, first, a model describing the health assessment process to show how self-rated health can reflect the states of the human body and mind. Here, an analytic distinction is made between the different types of information on which people base their health assessments and the contextual frameworks in which this information is evaluated and summarized. The model helps us understand why self-ratings of health may be modified by age or culture, but still be a valid measure of health status. Second, based on the proposed model, the paper examines the association of self-rated health with mortality. The key question is, what do people know and how do they know what they know that makes self-rated health such an inclusive and universal predictor of the most absolute biological event, death. The focus is on the social and biological pathways that mediate information from the human organism to individual consciousness, thus incorporating that information into self-ratings of health. A unique source of information is provided by the bodily sensations that are directly available only to the individual him- or herself. According to recent findings in human biology, these sensations may reflect important physiological dysregulations, such as inflammatory processes. Third, the paper discusses the advantages and limitations of self-rated health as a measure of health in research and clinical practice. Future research should investigate both the logics that govern people's reasoning about their health and the physiological processes that underlie bodily feelings and sensations. Self-rated health lies at the cross-roads of culture and biology, therefore a collaborative effort between different disciplines can only improve our understanding of this key measure of health status.

The effect of dementia trends and treatments on longevity and disability: a simulation model based on the MRC Cognitive Function and Ageing Study (MRC CFAS)

BACKGROUND

the numbers with dementia are projected to double between 2001 and 2040, in line with continued increases in life expectancy. Projections have failed to account for the impact of changing risk factors on future numbers with dementia or disability.

OBJECTIVE

to estimate the size of the disabled population over the next 20 years and explore the impact of treatments that delay onset of cognitive impairment and associated disability.

METHODS

a dynamic macro-simulation projection model was used to calculate the numbers of older people with disability to 2026. Transition rates to disability and death conditional on a range of conditions, calculated from the MRC Cognitive Function and Ageing Study, were applied to the 1992 England and Wales population. Scenarios for trends in dementia incidence, risk factors and treatment were devised from a systematic review and applied.

FINDINGS

population ageing alone resulted in 39% more older people between 2006 and 2026 and 82% more with disability. A combination of reduced incidence of cognitive impairment and disabling consequences alongside improved survival provided the largest reductions in the disabled population (15,000) and the numbers cognitively impaired (302,000) compared with ageing of the population alone.

INTERPRETATION

population ageing alone will increase the disabled older population by over 80% and the numbers cognitively impaired by almost 50% over the next 20 years with serious implications for the provision of care. Research priorities should focus on earlier detection of dementia and its risk factors, thereby allowing earlier and more targeted treatment to alleviate its associated disability.

Increasing levels of semantic verbal fluency in elderly English adults

Analyses incorporating large independent population-based samples and identical measures are needed to investigate recent trends in cognitive function. Nationally representative independent cohorts of community living individuals in England aged 65 years or older from the MRC Cognitive Function and Ageing Study in 1991 (n = 9458) and the English Longitudinal Study of Ageing in 2002 (n = 5196) were compared. East Cambridgeshire participants aged 65-69 years in 1991 (n = 680) were also compared to an independent cohort examined in 1996 (n = 600). Semantic verbal fluency, as measured by the animal naming neuropsychological test, increased by 1.1 extra words a minute in England between 1991 and 2002 (95% CI 0.9, 1.3). A similar increase was also observed in East Cambridgeshire. Levels of semantic verbal fluency appear to have increased in the older English population, which may help to buffer the aging population from future increases in dementia.