Amin, Vikesh

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Now showing 1 - 5 of 5
  • Publication
    Resilience, Accelerated Aging and Persistently Poor Health: Diverse Trajectories of Health among the Global Poor
    (2022-08-01) Kohler, Iliana V; Hoang, Cung Truong; Amin, Vikesh; Behrman, Jere R; Kohler, Hans-Peter
    Objectives: This study is among the first to document lifecourse trajectories of physical and mental health across adult and older ages (20-70 years) for a poor sub-Saharan African population having faced frequent and sustained adversities. Methods: The 2006-19 waves of the Malawi Longitudinal Study of Families and Health (MLSFH) were analyzed using group-based trajectory models (GBTM) to identify trajectories of heath (SF12 mental/physical health and BMI) across the lifecourse. Predictors of trajectory membership were estimated using fractional multinomial logits. Results: Analyses identified three distinct trajectories: (1) good initial mental/physical health that persisted throughout the lifecourse ("resilient aging"); (2) good initial mental and physical health that deteriorated with age ("accelerated aging"); or (3) poor initial mental and physical health with possibly further declines over the lifecourse ("aging with persistently poor health"). Predictors of trajectory group membership included gender, childhood poverty, and schooling. Discussion: Despite lifecourses being characterized by poverty and frequent adversities in this poor population, our analyses identified a sizable group (30%) of resilient individuals who experienced successful aging with good initial health that persisted across the lifecourse and into old age. Accelerated aging was the most common trajectory for SF12 physical and mental health in this poor population, while for BMI, persistently poor health was most common. Men were more likely to enjoy resilient aging than women in terms of physical/mental health, contrary to previous findings from high-income contexts. Other predictors of trajectory membership sometimes confirmed, and sometimes contradicted, hypotheses derived from high-income country studies.
  • Publication
    Mental Health, Schooling Attainment and Polygenic Scores: Are There Significant Gene-Environment Associations?
    (2020-02-04) Amin, Vikesh; Behrman, Jere R.; Fletcher, Jason M.; Flores, Carlos A.; Flores-Lagunes, Alfonso; Kohler, Hans-Peter
    We estimate associations between a polygenic score (PGS) for depressive symptoms, schooling attainment and genetic-environmental (GxE) associations with depressive symptoms and depression for 29 years old in the National Longitudinal Study of Adolescent Health (Add Health) and 53 years old in the Wisconsin Longitudinal Study (WLS). We find some suggestive evidence that the association of the PGS with mental health is lower for more-schooled older individuals in the WLS, but no evidence in Add Health. Quantile regression estimates also show that in the WLS the GxE associations are statistically significant only in the upper parts of the conditional depressive symptoms score distribution. We assess the robustness of the OLS results to possible omitted variable bias by estimating sibling fixed-effect regressions. The sibling fixed-effect results must be qualified, in part due to low statistical power. However, they show that college education is associated with fewer depressive symptoms in both datasets.
  • Publication
    Does Schooling Improve Cognitive Abilities at Older Ages: Causal Evidence from Nonparametric Bounds
    (2022-05-19) Amin, Vikesh; Behrman, Jere R.; Fletcher, Jason M.; Flores, Carlos A.; Flores-Lagunes, Alfonso; Kohler, Hans-Peter
    We revisit the much-investigated relationship between schooling and health, focusing on cognitive abilities at older ages using the Harmonized Cognition Assessment Protocol in the Health & Retirement Study. To address endogeneity concerns, we employ a nonparametric partial identification approach that provides bounds on the population average treatment effect using a monotone instrumental variable together with relatively weak monotonicity assumptions on treatment selection and response. The bounds indicate potentially large effects of increasing schooling from primary to secondary but are also consistent with small and null effects. We find evidence for a causal effect of increasing schooling from secondary to tertiary on cognition. We also replicate findings from the Health & Retirement Study using another sample of older adults from the Midlife in United States Development Study Cognition Project.
  • Publication
    Heterogenous Trajectories in Physical, Mental and Cognitive Health among Older Americans: Roles of Genetics and Earlier SES
    (2021-09-12) Hoang, Cung Truong; Amin, Vikesh; Behrman, Jere R.; Kohler, Hans-Peter; Kohler, Iliana V.
    We investigate the roles of genetic predispositions, childhood SES and adult schooling attainment in shaping trajectories for three important components of the overall health and wellbeing of older adults -- BMI, depressive symptoms and cognition. We use the Health & Retirement Study (HRS) and group-based trajectory modelling (GBTM) to identify subgroups of people who share the same underlying trajectories over ages 50-94 years. After identifying common underlying trajectories, we use fractional multinomial logit models to estimate associations of (1) polygenic scores for BMI, depression, ever-smoked, education, cognition and subjective wellbeing, (2) childhood SES and (3) schooling attainment on the probabilities of trajectory group membership. While genetic predispositions do play a part in predicting trajectory group membership, our results highlight the long arm of socioeconomic factors. Schooling attainment is the most robust predictor—it predicts increased probabilities of belonging to trajectories with BMI in the normal rage, low depressive symptoms and high initial cognition. Childhood circumstances are manifested in trajectories to a lesser extent, with childhood SES only predicting the likelihood of being on the low depressive symptoms trajectory. We also find suggestive evidence that associations of schooling attainment on the probabilities of being on trajectories with BMI in the normal rage, low depressive symptoms and high initial cognition vary with genetic predispositions.
  • Publication
    Genetic Risks, Adolescent Health and Schooling Attainment
    (2020-06-25) Amin, Vikesh; Behrman, Jere R.; Fletcher, Jason M.; Flores, Carlos A.; Flores-Lagunes, Alfonso; Kohler, Hans-Peter
    We provide new evidence on the effect of adolescent health behaviors/outcomes (obesity, depression, smoking, and attention deficit hyperactivity disorder (ADHD)) on schooling attainment using the National Longitudinal Study of Adolescent to Adult Health. We take two different approaches to deal with omitted variable bias and reverse causality. Our first approach attends to the issue of reverse causality by using health polygenic scores (PGSs) as proxies for actual adolescent health. Second, we estimate the effect of adolescent health using sibling fixed-effects models that control for unmeasured genetic and family factors shared by siblings. We use the PGSs as additional controls in the sibling fixed-effects models to reduce concerns about residual confounding from sibling-specific genetic differences. We find consistent evidence across both approaches that being genetically predisposed to smoking and smoking regularly in adolescence reduces schooling attainment. We find mixed evidence for ADHD. Our estimates suggest that having a high genetic risk for ADHD reduces grades of schooling, but we do not find any statistically significant negative effects of ADHD on grades of schooling. Finally, results from both approaches show no consistent evidence for a detrimental effect of obesity or depression on schooling attainment.