Swiss Interdisciplinary Longitudinal Study Research Articles

Bereavement in Very Old Age: Impact on Health and Relationships of the Loss of a Spouse, a Child, a Sibling, or a Close Friend

This article deals with the following two questions: In very old age, which are the main sources of bereavement? And what are the consequences of such losses on health and on relationships? The findings are based on the complete set of data compiled in the course of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSOO), which provided a 10-year follow-up of a first cohort (1994-2004) and a 5-year follow-up of a second (1999-2004). The data revealed that, in very old age, the great majority of the dear ones who died were either siblings or close friends. Taken as a whole, the bereaved suffered a marked and lasting increase in depressive symptoms, together with a short-term deterioration in their functional status; those bereft of a spouse or a child saw their functional status worsen and exhibited enduring depressive symptoms but they also benefited from support in the form of increased interaction; those bereft of siblings only suffered from a mild, short-term deterioration in functional status; those who had lost a close friend suffered a very significant increase in depressive symptoms. In the medium term, most of these effects disappeared, lending weight to the claim that the survivors manage to cope with the misfortunes of life.

The interface between formal and informal support in advanced old age: A 10-year study

The aim of this paper is to investigate the interface between the formal and informal support provided to very old people against a background of increasing need for care and a decreasing number of potential informal caregivers. We used a sample of 323 community-dwelling octogenarians participating in the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSOO) (n=1441 interviews). Descriptive analyses and a multilevel model were used to test whether formal and informal services complemented or substituted one another. The study revealed that the amount of informal services increased significantly as the frequency of formal aid increased, indicating that the two networks were complementary in the majority of the cases. In 21.2% of the cases, the formal network partly substituted the informal network (as an adjustment) and only in 6.4% of the cases did the informal support end after the formal support had increased (radical substitution). The concern that the introduction of formal services may curb the readiness of relatives and friends to provide care is thus unfounded.

Health perception and health status in advanced old age: A paradox of association

This paper deals with the relationship between health status and health perception in very advanced age. We examine how older people assess their own health and at the same time we investigate the equivalence between their health status and the perception they have of it. Based on quantitative and qualitative data collected under the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSOO), this analysis confirms that, while both health status and self-rated health deteriorate in very old age, people aged 80 and over tend to underestimate the decline. We show that the widening gap between perceived and objective health status can be accounted for by mechanisms of comparison. The qualitative data point to the use of various forms of comparison which allow older people to maintain a relatively favourable perception of their own health — and therefore of themselves — until a very advanced age.

Application of a Joint Multivariate Longitudinal–Survival Analysis to Examine the Terminal Decline Hypothesis in the Swiss Interdisciplinary Longitudinal Study on the Oldest Old

In this work I aim at extending current knowledge on the terminal decline hypothesis by applying a joint multivariate longitudinal-survival analysis to the cognitive data of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old. (In that study, 529 individuals between 79 and 85 years of age at study inception were assessed up to five times on a task of perceptual speed and one of verbal fluency.) I simultaneously estimated a multivariate, multilevel longitudinal model and a Weibull survival model to test whether individual performance and change in speed and fluency predict survival, controlling for retest effects, initial age, gender, overall health, socioeconomic status, and sensory functioning. Results revealed that age and performance level in fluency predicted survival, whereas level in speed and change in both cognitive variables did not. I discuss the relevance of fluency tasks in predicting mortality.

Social Status and Mortality With Activity of Daily Living Disability in Later Life

The aim of this study was to assess which social status factors predispose a person to dying with activity of daily living (ADL) disability in later life. We followed 243 deceased members of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old annually up to 8 years before their deaths. Using a multilevel regression, we analyzed age at death, gender, occupational category, and geographic area as potential factors predisposing a person to ending life with ADL disability. Disability scores showed a substantial increase as death approached. Individuals from a lower occupational category were at higher risk of ADL disability and experienced a greater functional decline prior to death compared to those from higher occupational categories. Consistent with the cumulative disadvantage theoretical framework, the health differential between the occupational categories seems to be exacerbated prior to death.

Dynamics of Frailty and ADL Dependence in a Five-Year Longitudinal Study of Octogenarians

Using a sample of octogenarians from the Swiss Interdisciplinary Longitudinal Study on the Oldest Old, the authors investigated the predictive validity of an expanded working definition of frailty based on deficiencies in mobility, memory, energy, and physical or sensory capacities and analyzed the resulting health transitions. The five domains were considered as predictors of the onset of dependence in activities of daily living (ADLs) and death using logistic multilevel and Cox survival regression models. Health transitions were studied with Markov chains. Deficiencies in memory, energy, and sensory capacities contributed to the prediction of the onset of ADL dependence and death in participants free of physical pains and mobility impairments. With two domains affected, frailty in very old persons indicated an increased risk of adverse outcomes. The study of transitions showed that ADL-independent frailty was a highly probable and relatively long transitional stage between robustness and ADL dependence.

Health: support provided and received in advanced old age

While research focuses mainly on support provided to the elderly, this paper deals with the very old as a support provider to his family as much as a care recipient from both his family and a formal network. We hypothesize that elders with declining health will try to maintain the provision of services, even when they require and receive help.A total of 340 octogenarians from the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSOO) were interviewed up to five times over five years (N=1225 interviews). A multilevel model was applied to assess the effects of health, controlled for socio-demographic and family network variables, on the frequency of services that the old persons provided to their family and received from their family and formal networks. Health is operationalized in three statuses: ADL-dependent, ADL-independent frail, and robust.While the recourse to the informal network increased progressively with the process of frailty, the recourse to the formal network drastically increased for ADL-dependent individuals. Being ADL-dependent seriously altered the capacity to provide services, but ADL-independent frail persons were providers with the same frequency as the robust oldest old, showing their ability to preserve a principle of reciprocity in their exchanges with their family network. This continuity of roles may help frail persons to maintain their self-esteem and well-being.

How are Temporal and Social Comparisons Related to Appraisals of Self-Rated Health During Very Old Age?

This study investigated the direction of effects of temporal and downward social comparisons on self-rated health in very old age. Conversely, self-rated health can either reinforce or hinder comparison processes. In the framework of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old, individuals aged 80 to 84 at baseline were interviewed and followed longitudinally for 5 years. Multilevel analyses were used to test the relative importance of temporal and social comparisons on self-rated health evaluations synchronically and diachronically (with a time lag of 12 to 18 months) as well as the direction of these relative influences. Results indicate that (a) at the synchronic level, continuity temporal comparisons have more impact than downward social comparisons on self-rated health; (b) both types of comparison had an independent and positive effect on self-rated health at the diachronic level; (c) self-rated health has an independent synchronic effect on both types of comparison and an independent diachronic effect in temporal comparison.

Does Activity Engagement Protect Against Cognitive Decline in Old Age? Methodological and Analytical Considerations

The literature about relationships between activity engagement and cognitive performance is abundant yet inconclusive. Some studies report that higher activity engagement leads to lower cognitive decline; others report no functional links, or that higher cognitive performance leads to less decline in activity engagement. We first discuss some methodological and analytical features that may contribute to the divergent findings. We then apply a longitudinal dynamic structural equation model to five repeated measurements of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old. Performance on perceptual speed and verbal fluency tasks was analyzed in relation to six different activity composite scores. Results suggest that increased media and leisure activity engagement may lessen decline in perceptual speed, but not in verbal fluency or performance, whereas cognitive performance does not effect change in activity engagement.

The impact of social relationships on the maintenance of independence in advanced old age: findings of a Swiss longitudinal study

The impact of social relationships on the maintenance of independence over periods of 12-18 months in a group of 306 octogenarians is assessed in this study. The study is based on the results of the Swilsoo (Swiss Interdisciplinary Longitudinal Study on the Oldest Old). Participants (80-84 years old at baseline) were interviewed five times between 1994 and 1999. Independence was defined as the capacity to perform without assistance eight activities of daily living. We distinguished in our analyses kinship and friendship networks and evaluated social relationships with the help of a series of variables serving as indicators of network composition and contact frequency. Logistic regression models were used to identify the short-term effects of social relationships on independence, after controlling for sociodemographic and health-related variables; independence at a given wave of interviews was interpreted in the light of social factors measured at the previous wave. Our analyses indicate that the existence of a close friend has a significant impact on the maintenance of independence (OR=1.58, p<0.05), which is not the case with the other variables concerning network composition. Kinship contacts were also observed to have a positive impact on independence (OR=1.12, p<0.01).

A dynamic investigation of cognitive dedifferentiation with control for retest: Evidence from the Swiss Interdisciplinary Longitudinal Study on the Oldest Old.

Empirical examinations of the hypothesis of dedifferentiation of cognitive abilities in old and very old age (a) do not account for possible retest effects, which consequently may yield biased estimates of age effects, and (b) focus on time-independent relations (e.g., number of latent constructs, correlations between latent or measured variables). The authors applied a structural equation model with statistical control for retest effects to investigate the dynamic relations between a marker of perceptual speed (cross out) and a marker of verbal fluency (category-fruits). Longitudinal data are from 5 waves of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (N = 377, baseline age range = 79.5- 84.5 years). The authors found that, independently of retest effects, performance on the cross-out task affected changes in performance on the category task while the opposite did not hold true. This analytical technique could be applied to various markers of broad fluid-mechanic and broad crystallized-pragmatic components of cognition.

An Introduction to Generalized Estimating Equations and an Application to Assess Selectivity Effects in a Longitudinal Study on Very Old Individuals

Correlated data are very common in the social sciences. Most common applications include longitudinal and hierarchically organized (or clustered) data. Generalized estimating equations (GEE) are a convenient and general approach to the analysis of several kinds of correlated data. The main advantage of GEE resides in the unbiased estimation of population-averaged regression coefficients despite possible misspecification of the correlation structure. This article aims to provide a concise, nonstatistical introduction to GEE. To illustrate the method, an analysis of selectivity effects in the Swiss Interdisciplinary Longitudinal Study on the Oldest Old is presented.

Static and Dynamic Longitudinal Structural Analyses of Cognitive Changes in Old Age

Background: Among the main data-analytical advances of recent decades are Latent Growth Models (LGM) and Multilevel Models (MLM) for the analysis of longitudinal data. Objective: We discuss the relative advantages and disadvantages of the two analytical methods and offer some practical guidelines concerning the choice between LGM and MLM based on (a) completeness and balance of the data, (b) theoretical functional form of change examined, (c) examination of the error structure, (d) theoretical relations among differential level effects and differential change effects, and (e) role of time-invariant covariates. Methods: To discuss LGM and MLM, we provide illustrations from applications to the Berlin Aging Study (BASE) and the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSO-O). Results: As predicted by two-component theories of lifespan cognition, performance on a vocabulary test (indicator of broad crystallized intelligence) did not decline over time, while scores on a digit letter test (indicator of broad fluid intelligence) decreased over 6 years. Differential level effects were obtained on both variables, while average and differential change effects were obtained only for the digit letter test. In a second set of analyses, we tested the error-free effect that a broad fluid intelligence indicator exerted on the latent yearly change in a broad crystallized intelligence indicator, and vice versa. In both data sets we obtained strong evidence for a more reliable effect of the fluid indicator on the change in the crystallized indicator. This evidence provided support for the dedifferentiation hypothesis of cognitive abilities in very old age. Conclusions: New insights into cognitive aging phenomena can be gained with proper applications of LGM and MLM. We posit that the choice between LGM and MLM and their specification rests on theoretical and empirical motives to be defined a priori.

Religiousness and Survival in the Swiss Interdisciplinary Longitudinal Study on the Oldest Old

Survival in old age has been shown to be positively related to religiousness, and in particular to to church attendance. This research provides new confirmation of this relationship under the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (N = 340 at baseline), a study following subjects aged 80 to 84 at baseline since 1994. Results of logistic regression analyses indicate that participation in church services or a composite measure of religiousness comprising participation in services and the frequency of prayer is positively related to survival in a time interval of 12 to 18 months, controlling for other possible explanatory factors such as functional health or depressive symptoms. To our knowledge, this is the first time that this effect has been demonstrated in a population of old old subjects and in a Latin country of Europe where the number of Catholic subjects is high.