Philippa Clarke

Space meets time: Integrating temporal and contextual influences on mental health in early adulthood

The integration of temporal life course perspectives and current social context perspectives is considered as a framework for the understanding of mental health differences in early adulthood, a formative stage in the development of long-term mental health differences. Using data from the National Survey of Children and a cross-nested random effects model to simultaneously assess the effects of current and past neighborhood, the authors find a lagged effect of childhood neighborhood socioeco-nomic disadvantage on early adult mental health, while accounting for initial mental health status. This lagged effect also explains the apparent (bivariate) effect of current neighborhood. Four hypotheses are assessed to explain the lagged effect of neighborhood: contextual continuity, mental health continuity, life course stress accumulation, and ambient chronic stress in the neighborhood. Support is found for a cumulative mediating effect of both life course stress and ambient neighborhood stress as children grow up; together, these variables entirely explain the lagged effect of early neighborhood. Findings suggest the need for a more temporal life course approach to the specification of social context effects in general, focusing on the history of social contexts that individuals live in and move through. Temporal-contextual perspectives also encourage a focus on theoretical models that can differentially locate formative contextual influences at different stages in the life course

When can group level clustering be ignored? Multilevel models versus single-level models with sparse data

Objective: The use of multilevel modelling with data from population-based surveys is often limited by the small number of cases per level-2 unit, prompting many researchers to use single-level techniques such as ordinary least squares regression. Design: Monte Carlo simulations are used to investigate the effects of data sparseness on the validity of parameter estimates in two-level versus single-level models. Setting: Both linear and non-linear hierarchical models are simulated in order to examine potential differences in the effects of small group size across continuous and discrete outcomes. Results are then compared with those obtained using disaggregated techniques (ordinary least squares and logistic regression). Main results: At the extremes of data sparseness (two observations per group), the group level variance components are overestimated in the two-level models. But with an average of only five observations per group, valid and reliable estimates of all parameters can be obtained when using a two-level model with either a continuous or a discrete outcome. In contrast, researchers run the risk of Type I error (standard errors biased downwards) when using single-level models even when there are as few as two observations per group on average. Bias is magnified when modelling discrete outcomes. Conclusions: Multilevel models can be reliably estimated with an average of only five observations per group. Disaggregated techniques carry an increased risk of Type I error, even in situations where there is only limited clustering in the data.

The Role of the Built Environment in the Disablement Process

The Disablement Process model explicates the transition from health conditions to disability and specifically emphasizes the role of intervening factors that speed up or slow down the pathway between pathology and disability. We used hierarchical Poisson regression analyses with data on older adults from central North Carolina to examine the role of the built environment as a modifying factor in the pathway between lower extremity functional limitations and activities of daily living. We found that, despite declining physical function, older adults report greater independence in instrumental activities when they live in environments with more land-use diversity. Independence in self-care activities is modified by housing density, in part through the effect of substandard and inadequate housing.

Mobility Disability and the Urban Built Environment

Research on the effects of the built environment in the pathway from impairment to disability has been largely absent. Using data from the Chicago Community Adult Health Study (2001-2003), the authors examined the effect of built environment characteristics on mobility disability among adults aged 45 or more years (n = 1,195) according to their level of lower extremity physical impairment. Built environment characteristics were assessed by using systematic social observation to independently rate street and sidewalk quality in the block surrounding each respondents residence in the city of Chicago (Illinois). Using multinomial logistic regression, the authors found that street conditions had no effect on outdoor mobility among adults with only mild or no physical impairment. However, among adults with more severe impairment in neuromuscular and movement-related functions, the difference in the odd ratios for reporting severe mobility disability was over four times greater when at least one street was in fair or poor condition (characterized by cracks, potholes, or broken curbs). When all streets were in good condition, the odds of reporting mobility disability were attenuated in those with lower extremity impairment. If street quality could be improved, even somewhat, for those adults at greatest risk for disability in outdoor mobility, the disablement process could be slowed or even reversed.

Well-being after stroke in Canadian seniors: findings from the Canadian Study of Health and Aging.

Background and Purpose— After a stroke many people continue to live with their residual impairments and disabilities in the community, which can pose a significant problem for survivors’ well-being. The purpose of this research was to investigate patterns of well-being in community-dwelling stroke survivors to identify those factors that restrict and enhance well-being. Methods— A secondary analysis was conducted on data from the second wave of the Canadian Study of Health and Aging (CSHA-2). A national sample of 5395 community-dwelling Canadian seniors (aged ≥65 years) was interviewed for CSHA-2, including 339 stroke survivors (6.3%). Information was collected on health, social and demographic characteristics, and well-being. Comparisons were made between the health and functional status of stroke survivors and community-dwelling seniors who have not experienced a stroke. Multiple regression was used to examine the factors associated with well-being in stroke survivors. Results— Compared with community-dwelling seniors who have not experienced a stroke, stroke survivors report a lower sense of well-being. Stroke survivors are also more likely to be restricted in their physical and cognitive function, to report worse mental health, and to be living with a greater number of comorbid health conditions. Mental health and physical and cognitive disabilities are associated with a reduced sense of well-being in stroke survivors, but social supports and educational resources moderate the impact of functional status on well-being. Conclusions— Community-dwelling seniors who have had a stroke experience a reduced sense of well-being. However, social resources can help to alleviate the subjective burden of this common neurological condition.

Measuring Psychological Well-Being in the Canadian Study of Health and Aging

The Canadian Study of Health and Aging (CHSA) provided an opportunity to examine the positive aspects of aging. CHSA-2 included the 18-item Ryff multidimensional measure of well-being, which taps six core theoretical dimensions of positive psychological functioning. The measure was administered to 4,960 seniors without severe cognitive impairment or dementia at CSHA-2. Intercorrelations across scales were generally low. At the same time, the internal consistency reliability of each of the 6 subscales was not found to be high. Confirmatory factor analyses provide support for a 6-factor model, although some items demonstrate poor factor loadings. The well-being measures in CSHA-2 provide an opportunity to examine broad, descriptive patterns of well-being in Canadian seniors.

Environments for healthy ageing: A critical review

Population health outcomes are shaped by complex interactions between individuals and the environments in which they live, work and play. Environments encompass streets and buildings (physical environment), attitudes, supports and relationships with others (social environment), as well as social and political systems and policies. The impact of environments on the physical, mental health and functioning of individuals has emerged as a growing body of research in population health and health disparities. Yet, the majority of studies in this area do not focus on older adults even though older adults are particularly susceptible to the characteristics of their local environments. In this paper we review the current state of the health literature on physical environments for healthy ageing, using the International Classification of Functioning Disability and Health as a framework. Collectively, the literature emphasizes the role of supportive, barrier-free environments particularly for older adults who are at greater risk for disability and poor health. As part of our review we identify conceptual as well as methodological limitations in the current literature, including (i) a theoretical and empirical neglect of the underlying mechanisms behind the person-environment relationship; (ii) a lack of studies using nationally representative samples; (iii) over-reliance on cross-sectional data; and (iv) a need for better definition and measurement of person-centered environments. We conclude by offering some suggestions and directions for future research in this area.

Quality of life following stroke : Negotiating disability, identity, and resources

Residual physical and cognitive impairments following a stroke can pose a significant threat to a survivor’s quality of life. Yet, there is not always a direct one-to-one correlation between functional disability and subjective quality of life. This research investigated the complexity of factors that influence quality of life after stroke, using qualitative interviews. Results indicate that a stroke has a significant impact on the quality of life of survivors, but some individuals find ways to adapt to their functional disabilities and report a high quality of life. Common elements of this process consist of reordering priorities to focus on those activities considered most salient to an individual’s identity; then drawing on existing resources, including health services and social supports, to maintain a customary activity, even in a modified form, retaining salient aspects of the individual’s identity and maintaining a sense of continuity in his or her life.

Addressing Data Sparseness in Contextual Population Research

The use of multilevel modeling with data from population-based surveys is often limited by the small number of cases per Level 2 unit, prompting a recent trend in the neighborhood literature to apply cluster techniques to address the problem of data sparseness. In this study, the authors use Monte Carlo simulations to investigate the effects of marginal group sizes on multilevel model performance, bias, and efficiency. They then employ cluster analysis techniques to minimize data sparseness and examine the consequences in the simulations. They find that estimates of the fixed effects are robust at the extremes of data sparseness, while cluster analysis is an effective strategy to increase group size and prevent the overestimation of variance components. However, researchers should be cautious about the degree to which they use such clustering techniques due to the introduction of artificial within-group heterogeneity.

Well being in Canadian seniors: Findings from the Canadian Study of Health and Aging.

While aging is associated with increased health problems and disability, most seniors subjectively rate their health positively, and view aging as a positive period of life evaluation, increased wisdom and maturity. The somewhat paradoxical nature of these findings suggests that later life well-being is multidimensional and variable. Drawing on data from a nationally representative survey, this paper describes the subjective well-being of a sample of Canadian seniors, using the Ryff multidimensional measure of well-being, and investigates the effects of various demographic, health and socio-economic conditions on reported levels of well-being. Seniors’ well-being is robust in terms of the dimension of autonomy, which is resilient to the physical and social circumstances of later life. But, as seniors age, they experience declines in their sense of purpose in life and opportunities for personal growth, in part, due to socio-economic factors. Good health and functional status are important for seniors’ sense of mastery over their surrounding world.