The essays in this dissertation explore issues related to health and retirement of older Americans, using longitudinal data on older Americans from ten waves of the Health and Retirement Study (1992-2010). The first essay explores the effect of both subjective and relatively more objective physical and mental health conditions on the probability of exit from full-time employment. Eight health indices (factors) are created from a wide range of health measures by principal component analysis. The effect of these health factors on the time until exit from full-time employment is empirically examined in a proportional hazard model. Single and competing risk specifications are estimated that allow for multiple spells of full-time employment and control for unobserved heterogeneity. The main results suggest that increase in functional limitation factor makes an individual more likely to exit via any route in general and the complete retirement route in particular. For mental health problems, increase in the depression factor increases the likelihood of exit from full-time employment via the complete retirement, part-time work and unemployment routes. While increase in cognitive disorders factor has no significant effect on the likelihood of exit via complete retirement, but increases the likelihood of exit via the disability route. These results have implications for public policies targeted towards retaining older workers within the labor market. The second essay examines the effect of retirement on post retirement physical and mental health and the extent to which the effects differ across these different health outcomes. The inherent issue of reverse causality between health and retirement that leads to endogeneity is addressed by using multiple sample stratification and instrumental variable estimation strategies. The stratified samples include individuals who are physically and mentally healthy prior to their retirement so that pure effect of retirement on post retirement health may be found. Five different instruments for complete retirement are also used to deal with endogeneity. The sample stratification results unanimously indicate that complete retirement has adverse effect on post retirement physical and mental health. While the instrumental variables approach results are mixed and are based on the choice of instrument for complete retirement.

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The theory of planned behaviour proposes that behaviour is predicted by behavioural intention which is, in turn, predicted by attitudes toward the behaviour, subjective norms regarding the behaviour and perceived control over the behaviour. Implied within this theory is that each of the three base components (attitudes, subjective norms and perceived behavioural control) influences intentions. However, despite being one of the most widely used theories in social psychology, few studies have investigated this basic premise. In addition, research on cognitive dissonance, public commitment, confirmation bias, implemental mindset, and the false consensus effect suggest that there may be a reverse-causal influence of intentions back on the base components of the theory. This potential reverse-causal sequence was tested in three studies. The first was correlational, the second was a lab-based experiment, and the third was a quasi-experimental field study. Study 1 employed a cross-lagged correlation design and showed that a reciprocal relation between intentions and base components was plausible. For the behaviour of supporting an environmental organization, Study 1 showed that attitudes were likely to influence intention-setting and that intention-setting subsequently influenced subjective norms. Study 2 employed a modified version of a free choice paradigm in which participants chose to set an intention to support one of two environmental organizations (using different support behaviours). Consequently participants rated the base components for the chosen organization higher and the rejected organization lower. However, this effect was primarily observed if participants were not initially committed to supporting an organization before the study began. Study 3 was a field study in which chemistry lab users who were exposed to an intervention that targeted behavioural intentions subsequently perceived more positive subjective norms (one aspect of subjective norms was changed). Together, the three studies demonstrate that a reverse-causal relation between intentions and base components is plausible and, thus, the theory of planned behaviour should be modified to include a reciprocal relation between these constructs. Intentions are most likely to influence base components that are least relevant to actual behaviour. When attitudes, subjective norms or perceived behavioural control are associated with actual behaviour, the one that is most strongly associated is least likely to change in response to setting an intention to engage in that behaviour. Other, less relevant, base components are more likely to change. / Graduate / 0451 / 0621 / 0768

Today, as we live longer, dementia diseases are becoming more prevalent around the world. Thus, further knowledge of how to maintain levels of cognitive functioning in old age and how to identify factors that postpone the onset of dementia are of acute interest. Lifestyle patterns and social life are important aspects to consider in this regard. This thesis includes three studies. Study I investigated the association between participation in various leisure activities in old age (≥65 years) and risk of incident all-cause dementia. Analyses of the total follow-up time period (15 years) showed that higher levels of “Social” and “Total” leisure activity were associated with decreased risk of dementia. In Study II, the aim was to investigate the association between various aspects of social relationships in old age (≥65 years) and risk of incidents of all-cause dementia and Alzheimer's disease. Results showed that over the total follow-up period (16 years) higher values on the relationship index were associated with reduced risk of both dementia and Alzheimer's disease. Visiting/visits of friends and acquaintances more than once a week was related to decreased risk for all-cause dementia, but not for Alzheimer's disease. However, in neither Study I nor II did any of these factors alter the risk of all-cause dementia or Alzheimer's disease when near-onset dementias were removed from the analyses (Study I, up to five years; Study II, up to three years). In Study III the aim was to investigate the association between social network size and cognitive ability in a middle-aged (40–60 years) sample. The idea was that if social network size can moderate negative age-related influence on memory functions, it might also put an individual on a cognitive trajectory that is beneficial in old age. Results from longitudinal analyses showed that baseline network size was positively related to five-year changes in semantic memory and with changes in both semantic and episodic memory at the ten-year follow-up. Social network size was unrelated to changes in visuospatial performance. Taken together, enrichment factors measured in old age (≥ 65 years) did not alter the risk of all-cause dementia or Alzheimer's disease when near-onset dementias were removed from the analyses. These results might reflect protective short-term effects or reverse causality, meaning that in the prodromal phase of dementia individuals tend to withdraw from activity. Social network size in middle age (40-60 years), however, appears to have beneficial long-term effects on cognitive functioning. The results highlight the importance of long follow-up periods and the need to adjust for the influences of reverse causality when investigating the impact of a socially and mentally active life on cognitive functioning.