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Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk.

ABSTRACT: Education is an established correlate of cognitive status in older adulthood, but whether expanding educational opportunities would improve cognitive functioning remains unclear given limitations of prior studies for causal inference. Therefore, we conducted instrumental variable (IV) analyses of the association between education and dementia risk, using for the first time in this area, genetic variants as instruments as well as state-level school policies.IV analyses in the Health and Retirement Study cohort (1998-2010) used two sets of instruments: (1) a genetic risk score constructed from three single-nucleotide polymorphisms (SNPs; n = 7981); and (2) compulsory schooling laws (CSLs) and state school characteristics (term length, student teacher ratios, and expenditures; n = 10,955).Using the genetic risk score as an IV, there was a 1.1% reduction in dementia risk per year of schooling (95% confidence interval, -2.4 to 0.02). Leveraging compulsory schooling laws and state school characteristics as IVs, there was a substantially larger protective effect (-9.5%; 95% confidence interval, -14.8 to -4.2). Analyses evaluating the plausibility of the IV assumptions indicated estimates derived from analyses relying on CSLs provide the best estimates of the causal effect of education.IV analyses suggest education is protective against risk of dementia in older adulthood.

SUBMITTER: Nguyen TT

PROVIDER: S-EPMC4688127 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk.

Nguyen Thu T TT Tchetgen Tchetgen Eric J EJ Kawachi Ichiro I Gilman Stephen E SE Walter Stefan S Liu Sze Y SY Manly Jennifer J JJ Glymour M Maria MM

Annals of epidemiology 20151030 1

<h4>Purpose</h4>Education is an established correlate of cognitive status in older adulthood, but whether expanding educational opportunities would improve cognitive functioning remains unclear given limitations of prior studies for causal inference. Therefore, we conducted instrumental variable (IV) analyses of the association between education and dementia risk, using for the first time in this area, genetic variants as instruments as well as state-level school policies.<h4>Methods</h4>IV anal ...[more]

PMID: 26633592

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Project description:BackgroundThere is ongoing debate about whether education or socioeconomic status (SES) should be inputs into cardiovascular disease (CVD) prediction algorithms and clinical risk adjustment models. It is also unclear whether intervening on education will affect CVD, in part because there is controversy regarding whether education is a determinant of CVD or merely correlated due to confounding or reverse causation. We took advantage of a natural experiment to estimate the population-level effects of educational attainment on CVD and related risk factors.Methods and findingsWe took advantage of variation in United States state-level compulsory schooling laws (CSLs), a natural experiment that was associated with geographic and temporal differences in the minimum number of years that children were required to attend school. We linked census data on educational attainment (N = approximately 5.4 million) during childhood with outcomes in adulthood, using cohort data from the 1992-2012 waves of the Health and Retirement Study (HRS; N = 30,853) and serial cross-sectional data from 1971-2012 waves of the National Health and Nutrition Examination Survey (NHANES; N = 44,732). We examined self-reported CVD outcomes and related risk factors, as well as relevant serum biomarkers. Using instrumental variables (IV) analysis, we found that increased educational attainment was associated with reduced smoking (HRS ? -0.036, 95%CI: -0.06, -0.02, p < 0.01; NHANES ? -0.032, 95%CI: -0.05, -0.02, p < 0.01), depression (HRS ? -0.049, 95%CI: -0.07, -0.03, p < 0.01), triglycerides (NHANES ? -0.039, 95%CI: -0.06, -0.01, p < 0.01), and heart disease (HRS ? -0.025, 95%CI: -0.04, -0.002, p = 0.01), and improvements in high-density lipoprotein (HDL) cholesterol (HRS ? 1.50, 95%CI: 0.34, 2.49, p < 0.01; NHANES ? 0.86, 95%CI: 0.32, 1.48, p < 0.01), but increased BMI (HRS ? 0.20, 95%CI: 0.002, 0.40, p = 0.05; NHANES ? 0.13, 95%CI: 0.01, 0.32, p = 0.05) and total cholesterol (HRS ? 2.73, 95%CI: 0.09, 4.97, p = 0.03). While most findings were cross-validated across both data sets, they were not robust to the inclusion of state fixed effects. Limitations included residual confounding, use of self-reported outcomes for some analyses, and possibly limited generalizability to more recent cohorts.ConclusionsThis study provides rigorous population-level estimates of the association of educational attainment with CVD. These findings may guide future implementation of interventions to address the social determinants of CVD and strengthen the argument for including educational attainment in prediction algorithms and primary prevention guidelines for CVD.

Project description:OBJECTIVES:The aim of this study was to critically explore the views of the public about the acceptability and feasibility of proactive approaches to earlier dementia diagnosis and also identification of people at high risk of dementia. DESIGN:Qualitative study using task group methodology and thematic data analysis. SETTING:Task groups were held either at the university (n=5) or at a carers' centre (n=1). PARTICIPANTS:A convenience sample of 31 of 54 participants identified by local non-statutory agencies took part in a task group. All were aged between 40 years and 80 years, 21 were women and 10men participated. RESULTS:Despite the use of task group methodology, participants expressed limited understandings of dementia and confusion between proactive approaches. Nevertheless, they highlighted a range of potential benefits and limitations of proactive approaches and the ethical issues raised. There was a preference to embed risk assessment within routine health checks, which focused on achieving a healthier lifestyle, rather than specifically on dementia. Participants emphasised the need to ensure informed consent prior to use of proactive approaches and to provide appropriate support. They also suggested alternative approaches that could potentially facilitate the early detection of dementia or reduce risk at a population level. CONCLUSIONS:As international policy on dementia shifts towards a prevention agenda there is growing interest in identifying those at risk of developing dementia. This study provides useful insights into the acceptability of the use of such proactive approaches among the public. The introduction of proactive approaches to dementia identification raises complex practical and ethical issues, particularly in the context of low public understanding of dementia. The importance of better quality information about dementia (and the likelihood of developing dementia) and provision of psychological support for those undergoing risk assessment were highlighted.

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Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk.

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Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk.

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