Genetic variants linked to education predict longevity

Bayesian association scan reveals loci associated with human lifespan and linked biomarkers

The enormous variation in human lifespan is in part due to a myriad of sequence variants, only a few of which have been revealed to date. Since many life-shortening events are related to diseases, we developed a Mendelian randomization-based method combining 58 disease-related GWA studies to derive longevity priors for all HapMap SNPs. A Bayesian association scan, informed by these priors, for parental age of death in the UK Biobank study (n=116,279) revealed 16 independent SNPs with significant Bayes factor at a 5% false discovery rate (FDR). Eleven of them replicate (5% FDR) in five independent longevity studies combined; all but three are depleted of the life-shortening alleles in older Biobank participants. Further analysis revealed that brain expression levels of nearby genes (RBM6, SULT1A1 and CHRNA5) might be causally implicated in longevity. Gene expression and caloric restriction experiments in model organisms confirm the conserved role for RBM6 and SULT1A1 in modulating lifespan.

Childhood IQ and survival to 79: Follow-up of 94% of the Scottish Mental Survey 1947

OBJECTIVE

To extend previous literature that suggests higher IQ in youth is associated with living longer. Previous studies have been unable to assess reliably whether the effect differs across sexes and ages of death, and whether the effect is graded across different levels of IQ.

METHODS

We test IQ-survival associations in 94% of the near-entire population born in Scotland in 1936 who took an IQ test at age 11 (n = 70,805) and were traced in a 68-year follow-up.

RESULTS

Higher IQ at age 11 years was associated with a lower risk of death (HR = 0.80, 95% CI = 0.79, 0.81). The decline in risk across categories of IQ scores was graded across the full range with the effect slightly stronger in women (HR = 0.79, 95% CI = 0.77, 0.80) than in men (HR = 0.82, 95% CI = 0.81, 0.84). Higher IQ had a significantly stronger association with death before and including age 65 (HR = 0.76, 95% CI = 0.74, 0.77) than in those participants who died at an older age (HR = 0.79, 95% CI = 0.78, 0.80).

CONCLUSIONS

Higher childhood IQ is associated with lower risk of all-cause mortality in both men and women. This is the only near-entire population study to date that examines the association between childhood IQ and mortality across most of the human life course.

Replication and characterization of CADM2 and MSRA genes on human behavior

Progress identifying the genetic determinants of personality has historically been slow, with candidate gene studies and small-scale genome-wide association studies yielding few reproducible results. In the UK Biobank study, genetic variants in CADM2 and MSRA were recently shown to influence risk taking behavior and irritability respectively, representing some of the first genomic loci to be associated with aspects of personality. We extend this observation by performing a personality "phenome-scan" across 16 traits in up to 140,487 participants from 23andMe for these two genes. Genome-wide heritability estimates for these traits ranged from 5-19%, with both CADM2 and MSRA demonstrating significant effects on multiple personality types. These associations covered all aspects of the big five personality domains, including specific facet traits such as compliance, altruism, anxiety and activity/energy. This study both confirms and extends the original observations, highlighting the role of genetics in aspects of mental health and behavior.

Beyond dual systems: A genetically-informed, latent factor model of behavioral and self-report measures related to adolescent risk-taking

The dual systems model posits that adolescent risk-taking results from an imbalance between a cognitive control system and an incentive processing system. Researchers interested in understanding the development of adolescent risk-taking use a diverse array of behavioral and self-report measures to index cognitive control and incentive processing. It is currently unclear whether different measures commonly interpreted as indicators of the same psychological construct do, in fact, tap the same underlying dimension of individual differences. In a diverse sample of 810 adolescent twins and triplets (M age=15.9years, SD=1.4years) from the Texas Twin Project, we investigated the factor structure of fifteen self-report and task-based measures relevant to adolescent risk-taking. These measures can be organized into four factors, which we labeled premeditation, fearlessness, cognitive dyscontrol, and reward seeking. Most behavioral measures contained large amounts of task-specific variance; however, most genetic variance in each measure was shared with other measures of the corresponding factor. Behavior genetic analyses further indicated that genetic influences on cognitive dyscontrol overlapped nearly perfectly with genetic influences on IQ (rA=-0.91). These findings underscore the limitations of using single laboratory tasks in isolation, and indicate that the study of adolescent risk taking will benefit from applying multimethod approaches.

Spillovers between siblings and from offspring to parents are understudied: A review and future directions for research

BACKGROUND

While a large literature has highlighted the protective effects of human capital on an individual's health and to some extent their offspring's health, little evidence is available on the positive spillover benefits of human capital for other family members. We conducted a scoping review of the evidence and identify future directions for research.

METHODS

We systematically searched the public health and economics literature on spillover effects from human capital, as indicated by educational attainment, to the health and/or survival of family members. We assessed (i) downward spillover effects (from parents and/or grandparents to offspring), (ii) horizontal spillover effects (from partners, spouses, and/or siblings), and (iii) upward spillover effects (from offspring to their parents and/or grandparents). We assessed the frequency of studies, their study designs, findings, and identified priority areas to inform future research on spillover effects of human capital.

FINDINGS

A total of 567 studies met our selection criteria. 286 studies assessed downward spillovers, 22 studies assessed horizontal spillovers, and five studies assessed upward spillovers. Studies on horizontal and upward spillovers found universally positive associations between additional education and better health in family members. The majority of studies used cross-sectional and longitudinal study designs as opposed to (quasi-)experimental designs. Further research is needed on horizontal and upward spillovers and research in low-resource settings, in addition to understanding what level of education matters the most, as well as mechanisms.

CONCLUSIONS

Although positive spillovers of human capital between siblings and from offspring to parents are likely, they have been understudied. Estimates of the returns to human capital that exclude these benefits may be too low.