Natural Symptoms? The Intersection of Social, Biological, and Genetic Determinants of Depression in Later Life

Purpose. This study explores the social, biological, and genetic determinants of depression in later life. It adds complexity to the idea that later life depression is a natural outgrowth of vascular impairment, antagonistic pleiotropy, or compromised neuroanatomical structures. Approach. The study uses the NAS-NRC Twin Registry of World War II Veterans. The use of twins allows for the exploration of gene-environment interplay. A recent survey instrument associated with the registry contains numerous indicators of health, as well as an established measure of geriatric depression. Findings. The results show that education has a strong negative relationship with depression among those in their 70s and early 80s. Although this relationship is partly explained by lower rates of cardiovascular disease and diabetes among the well-educated, the relationship between education and many common physical illnesses is quite small. Most people of this age experience at least one chronic illness. The relationship between education and depression is explained, instead, by reduced impairments in activities of daily living. These impairments are not an inevitable outgrowth of declining health. The well-educated are better able to moderate the impact of poor health on daily functioning. Moreover, the well educated are able to avoid the otherwise strong genetic risks for depression in later life. Gene × environment models show a high heritability for later life depression on average, but also reveal that this heritability declines with increasing education. Among those with a four-year college degree, the heritability of depression is very small. Value. These patterns are interpreted in light of models for understanding compensatory gene × environment interactions. These models emphasize the importance of especially enriched environments for overcoming genetic risk

When Mental Health Becomes Health: Age and the Shifting Meaning of Self-evaluations of General Health

Self-evaluations of general health are among the most widely-used measures of health status in research on the need for and outcomes of medical care. Yet, researchers know little about the psychological processes behind them. This study looks at whether such evaluations, often referred to as self-rated health, shift in what they measure as individuals age. Although several perspectives point to age-related shifts, few researchers have explicitly tested these perspectives against each other. The study tests several competing hypotheses using a large, nationally representative, and longitudinal data set. The results suggest two countervailing trends. First, the correspondence between functional limitations and self-rated health declines, especially after the age of 50. Similarly, the correspondence between a variety of chronic conditions and self-rated health, while strong, declines precipitously. Both of these findings are consistent with the idea that individuals evaluate their health through a process of social comparison and, in so doing, are able to maintain an elevated sense of general health even as they age. Yet, the results also suggest that the correspondence between depressive symptoms and self-rated health increases steadily throughout the life course. Indeed, after the age of 74, the correspondence between self-rated health and some common symptoms of depression becomes stronger than the correspondence between self-rated health and several chronic, and often fatal, somatic conditions. The implications of this crossover for both theory and policy are discussed. Among other things, the crossover has important implications for the detection and treatment of depressive symptoms in later life

Social Science Methods for Twins Data: Integrating Causality, Endowments and Heritability

Twins have been extensively used in both economic and behavioral genetics to investigate the role of genetic endowments on a broad range of social, demographic and economic outcomes. However, the focus in these two literatures has been distinct: the economic literature has been primarily concerned with the need to control for unobserved endowments—including as an im¬portant subset, genetic endowments—in analyses that attempt to establish the impact of one vari¬able, often schooling, on a variety of economic, demographic and health outcomes. Behavioral genetic analyses have mostly been concerned with decomposing the variation in the outcomes of interest into genetic, shared environmental and non-shared environmental components, with recent multivariate analyses investigating the contributions of genes and the environment to the correlation and causation between variables. Despite the fact that twins studies and the recogni¬tion of the role of endowments are central to both of these literatures, they have mostly evolved independently. In this paper we develop formally the relationship between the economic and behavioral genetic approaches to the analyses of twins, and we develop an integrative approach that combines the identification of causal effects, which dominates the economic literature, with the decomposition of variances and covariances into genetic and environmental factors that is the primary goal of behavioral genetic approaches. We apply this new integrative approach to an illustrative investigation of the impact of schooling on several demographic outcomes such as fertility and nuptiality and health

Where’s WALY? : A proof of concept study of the ‘wellbeing adjusted life year’ using secondary analysis of cross-sectional survey data

Background The Quality-Adjusted Life Year (QALY) is a measure that combines life extension and health improvement in a single score, reflecting preferences around different types of health gain. It can therefore be used to inform decision-making around allocation of health care resources to mutually exclusive options that would produce qualitatively different health benefits. A number of quality-of-life instruments can be used to calculate QALYs. The EQ-5D is one of the most commonly used, and is the preferred option for submissions to NICE (https://www.nice.org.uk/process/pmg9/). However, it has limitations that might make it unsuitable for use in areas such as public and mental health where interventions may aim to improve well-being. One alternative to the QALY is a Wellbeing-Adjusted Life Year. In this study we explore the need for a Wellbeing-Adjusted Life Year measure by examining the extent to which a measure of wellbeing (the Warwick-Edinburgh Mental Well-being Scale) maps onto the EQ-5D-3L. Methods Secondary analyses were conducted on data from the Coventry Household Survey in which 7469 participants completed the EQ-5D-3L, Warwick-Edinburgh Mental Well-being Scale, and a measure of self-rated health. Data were analysed using descriptive statistics, Pearson’s and Spearman’s correlations, linear regression, and receiver operating characteristic curves. Results Approximately 75 % of participants scored the maximum on the EQ-5D-3L. Those with maximum EQ-5D-3L scores reported a wide range of levels of mental wellbeing. Both the Warwick-Edinburgh Mental Well-being Scale and the EQ-5D-3L were able to detect differences between those with higher and lower levels of self-reported health. Linear regression indicated that scores on the Warwick-Edinburgh Mental Well-being Scale and the EQ-5D-3L were weakly, positively correlated (with R2 being 0.104 for the index and 0.141 for the visual analogue scale). Conclusion The Warwick-Edinburgh Mental Well-being Scale maps onto the EQ-5D-3L to only a limited extent. Levels of mental wellbeing varied greatly amongst participants who had the maximum score on the EQ-5D-3L. To evaluate the relative effectiveness of interventions that impact on mental wellbeing, a new measure – a Wellbeing Adjusted Life Year – is needed

Season of birth and depression in adulthood: Revisiting historical forerunner evidence for in-utero effects

Evidence showing a relationship between season of birth and adult well-being is long-standing, but is now largely overlooked or dismissed. In light of increasingly compelling evidence for the effects of in-utero conditions on adult health, however, it is instructive to revisit the relationship, with an eye toward resolving the reasons for skepticism. This study uses data from the first National Health and Nutritional Examination Survey to examine the effects of month of birth on adult depression. The data correspond to an important time in history and the analysis points to one reason why enthusiasm for birth seasonality in depression has faded: although there was a strong relationship between month of birth and depression in the early 20th century, with spring and summer month births corresponding to significantly more depression, the relationship was largely eliminated by the 1940 birth cohort. Few adults alive today would be subject to this effect, but when it was apparent it was enormously consequential. Population attributable risk scenarios indicate that among those born between 1900 and 1920 the prevalence of major depression would have been reduced by approximately 22% if all births had been confined to November through March. The percent rises to 26% among those born between 1900 and 1910, and was likely even higher in earlier cohorts. Additional analyses point to the importance of nutritional deficits in explaining these effects. In the early 20th century, the relationship between month of birth and depression was weaker in circumstances where the food supply was less seasonally sensitive. For this reason, the turn-of-the-century relationship between month of birth and depression was much weaker among the well-educated, in Southern states, and in urban areas. Although birth seasonality in depression can be regarded as a historical artefact of diet and nutrition, evidence for its prior existence nonetheless speaks to the significance of other in-utero effects, both past and present

An uncertain revolution: Why the rise of a genetic model of mental illness has not increased tolerance

This study uses the 2006 replication of the 1996 General Social Survey Mental Health Module to explore trends in public beliefs about mental illness in the USA. Drawing on three models related to the framing of genetic arguments in popular media, the study attempts to address why tolerance of the mentally ill has not increased, despite the growing popularity of a biomedical view. The key to resolving this paradox lies in understanding how genetic arguments interact with other beliefs about mental illness, as well as the complex ideational implications of genetic frameworks. Genetic arguments have contingent relationships with tolerance. When applied to schizophrenia, genetic arguments are positively associated with fears regarding violence. Indeed, in this regard, attributing schizophrenia to genes is no different from attributing schizophrenia to bad character. However, when applied to depression, genetic arguments are positively associated with social acceptance. In addition to these contingencies, genetic explanations have discontinuous relationships with beliefs regarding treatment. Although genetic arguments are positively associated with recommending medical treatment, they are not associated with the perceived likelihood of improvement. The net result of these assorted relationships is little change in overall levels of tolerance over time. Because of the blunt nature of the forces propelling a biomedical view--including the growing popularity of psychiatric medications--altering beliefs about the etiology of mental illness is unlikely, on its own, to increase tolerance.USA Genetics Beliefs about mental illness Public opinion Genes Stigma