Intelligence: is it the epidemiologists’ elusive “fundamental cause” of social class inequalities in health?

“Gottfredson (2004) suggests that general intelligence rather than self-control and attraction to risk is crucial to the relationship between SES and health.”

“This is perhaps the same reason why preexisting gaps between advantaged and less advantaged persons across different domains, including health and education, often widen when opportunities are made more equitable (Ceci & Papierno, 2005; Gottfredson, 2004).”

“The idea that g causes individual and group differences remains current, with recent arguments that g is the underlying cause of health inequalities among socioeconomic groups (Gottfredson, 2004 ).”

“…reviews of the relation of cognitive ability to occupational level have documented that higher average cognitive ability is associated with higher occupational level or income (e.g., Gottfredson 1998; 2004a,b; Nyborg & Jensen 2001; Schmidt & Hunter 2004; von Stumm et al. 2010; Zagorsky 2007).”

“49 Several basic features distinguish Gottfredson’s notion of intelligence from the concept of education as defined in this article: intelligence is regarded as “natural, not cultural,” “context-free,” and “highly heritable” – indicating a largely innate, biological foundation, little affected by…”

“With respect to morbidity, the predictive power of g is especially strong for the development of illnesses that are heavily dependent on behavioral self-regulation to prevent (e.g., diabetes; Gottfredson, 2004).”

“Persons with low levels of education or health literacy, both strongly related to IQ (9, 40), are less likely to appreciate when their conditions require medical attention, be aware of the appropriate actions to take when they do Pre-morbid IQ Disease and injury management”

“…and empirical work in the neurosciences (Gray & Thompson, 2004), behavior genetics (Bouchard, 1998; Posthuma et al., 2003), epidemiology (Gottfredson, 2004; Gottfredson & Deary, 2004; Hart et al., 2003), cognitive psychology (Deary, 2001; Kane et al., 2004; Mackintosh, 1998), and aging…”

“However, across all these domains there are individual differences that affect the development and maintenance of health literacy skills, including cognitive aptitude (Gottfredson, 2004), age-related cognitive decline (Baker, Gazmararian, et al., 2002), and preexisting knowledge.”

“And Gottfredson (2004) extends their argument to health-related behaviors in the context of the complexities encountered in modern life.”

“To this, Gottfredson takes the argument to the logical extreme, and argues that it is general intellectual ability (g), that explains the SES gradient and the appropriate fundamental cause of health outcomes in general (Gottfredson, 2004; Gottfredson & Deary, 2004).”

“Measures of intelligence relate to engagement of healthy behaviors, such as eating a healthy diet and exercising (Gottfredson, 2004).”

“Intelligence is one of the most robust predictors of conventional measures of educational achievement ​[5]​, job performance ​[6]​, socio-economic success ​[7]​, social mobility ​[8]​, health ​ [9]​ and longevity ​[10,11]​; and as life becomes increasingly complex, intelligence may play an ever increased role in life…”

“Academic achievement is essential for individual well-being across the lifespan (Gottfredson, 2004; Fiscella and Kitzman, 2009).”

“General cognitive ability and IQ are related to many important life outcomes, including academic success (13, 14), job performance (15), health (16, 17), morbidity (18), mortality (18, 19), income (20, 21), and crime (13).”

“With a fuller understanding of the causes of disparate health outcomes, more appropriate preventative measures can be developed and implemented (Gottfredson, 2004; Gottfredson & Deary, 2004).”

“…due to some third variable causing both, such as the unlikely theory that “intelligence” is responsible for apparent causal relationship between SES and health, then SES would not be a cause of health (Gottfredson 2004; Link, Phelan, Miech, and Westin 2008; Cutler and Lleras-Muney forthcoming).”

“…that neurocognitive factors may indeed be implicated in patterns of health behavior over the lifespan (Deary, Whiteman, Starr, Whalley, & Fox, 2004; Gottfredson, 2004; Gottfredson & Deary, 2004; Hart et al., 2003), and that executive functions may be especially central (Hall, Elias, & Crossley,…”

“frailty, and early mortality (Deary, Whiteman, Starr, Whalley, & Fox, 2004; Gottfredson, 2004).”

“…how family relations can influence cognitive ageing is important, not only because it predicts health outcomes and mortality (Batty et al. 2007; Gottfredson 2004; Whalley and Deary 2001), but also because it could help us learn how to improve the ability of older people to function in their…”

“…level (Bergman, Corovic, Ferrer-Wreder, & Modig, 2014) and is a positive indicator of high system integrity (Gale, Hatch, Batty, & Deary, 2009; Gale, Batty, Tynelius, Deary, & Rasmussen, 2010; Gottfredson, 2004; Lubinski & Humphreys, 1992; Wraw, Deary, Gale, & Der, 2015; Wrulich et al., 2013).”

“Thus, the IQ hypothesis has poised a historical threat to the illusion of an egalitarian society, generating a conflict between meritocracy and the very principle of egalitarianism (Gottfredson, 2004a; Herrnstein, 1973; Herrnstein, & Murray, 1994).”

“(1994) has made clear that substantive associations between intellectual capacity and physical morbidity and mortality do exist (e.g., Deary, Whiteman, Starr, Whalley, & Fox, 2004; Gottfredson, 2004), the social selection explanation for the income–health gradient has not been actively pursued.”

“For example, persons who experience poor health during childhood and adolescence, who have lower levels of intelligence, and/or whose parents were not highly educated may complete fewer years of schooling and die earlier than their counterparts, thus creating a statistical association between educational attainment an…”

“It may be the case that people with more education are more likely to recognise illness and subsequently seek treatment (Gottfredson, 2004).”

“Intelligence is a capacity strongly influenced by heredity (Gottfredson, 2004).”

“It is known that childhood intelligence is associated with diverse illness and health outcomes (Deary et al., 2010; Gottfredson, 2004; Lubinski, 2009).”

“They are also one of the best predictors available of family stability, criminality, health and lifespan (Gottfredson, 2004).”

“To account for the relationship between sociodemographic variables and health outcomes (see Gottfredson, 2004 ), we co-varied for participants’ age (Range = 79–97 years, M = 85.”

“The well-known association between Openness and intelligence should be acknowledged, given that intelligence has established connections to health (e.g., Deary, Whiteman, Starr, Whalley, & Fox, 2004; Gottfredson, 2004; Kanazawa, 2006).”

“In a related vein, intelligence and education are often associated with healthier lifestyle choices (Deary, Whalley, Batty, & Starr, 2006; Gottfredson, 2004).”

“Third, the association of intelligence with diverse health outcomes together with its pervasive influence on other important aspects of adult life (Gottfredson, 2004; Herrnstein & Murray, 1994) suggests that its effect on health may also be pervasive and act through a variety of mechanisms.”

“Gottfredson (2004) claims, on the basis of correlations only, that hereditary general ability is the basis of early inequalities, but that as children learn to adapt and adjust to their environment the relative importance of this ability declines.”

“The view, proposed by Gottfredson (13), that intelligence is the fundamental cause of social inequalities sees cognitive ability to be the driving force behind both socioeconomic attainment and health.”

“These results corroborate studies showing that IQ is negatively related to mortality over the life span (e.g. Batty, Deary, & Gottfredson, 2007; Batty, Deary,& Macintyre, 2007; Batty, Shipley, Mortensen, & Deary, 2008; Gottfredson, 2004).”

“Occupation: The type of work an individual engages in, often categorized by skill level, industry, and level of responsibility (Adler & Rehkopf, 2008; Gottfredson, 2004).”

“As children’s intelligence predicts later socio-economic success better than parents’ attributes ( Gottfredson, 2004 ), Glazer and Konrads Wnding is consistent with our claim that altruism and IQ are related.”

“lives (Gottfredson, 2004) that requires more than just knowing health-related words or being able to cope with health-related texts and math tasks.”

“It is also possible that individuals with more cognitive resources are better able to translate their traumatic event into a narrative(40) and make meaning out of it.(41,42) Developing programs that enhance meaning making or self-efficacy might be of substantial value for people such as military personnel and first re…”

“Although there have been suggestions that individual qualities, such as intelligence, time preference, or self-efficacy, could serve as confounding underlying determinants (13, 14), there is relatively little evidence for these as major explanatory variables (15).”

“Our fi ndings add to the evidence on the importance of intelligence as a predictor of later health (Lubinski & Humphreys, 1997; Gottfredson, 2004).”

“For example, when measures like the SAT are administered to 12-year-olds, who, in the seventh grade, score in the top few percentage points on conventional achievement tests, 1 Given the number of reports that suggest socioeconomic status (SES) influences cognitive ability measures in unknown ways, readers are referre…”

“These findings are in line with expectations formulated by several researchers in the field who suggested that the association between cognitive ability and health is mediated by the impact of cognitive ability on health related behaviours which, in turn, affects health and mortality [1-3,715,65].”

“Across dozens of studies, g correlates consistently with important, real-world outcomes, including educational achievement (Gottfredson, 2004b, 2005); income and wealth (Lynn & Vanhanen, 2006); health (Batty, Deary, & Gottfredson, 2007; Reeve, 2009), longevity (Deary, 2008), job performance (Hunter, 1993; Schmidt & Hu…”

“It also remains stable for much of adult life and is predictive of a wide range of important life outcomes (Gottfredson, 2004).”

“In respect to race, African Americans, for example, have IQ scores that are, on average, about 1 standard deviation below the IQ scores of Caucasians (Gottfredson, 2004; Rowe, 1994).”

“These would include partially heritable traits that influence SES such as intelligence (Gottfredson, 2004), aspects of personality (Caspi et al.”

“Secondly, the health measures are all self-reported, which may bias the estimates since education 1See Gottfredson (2004) for an overview of the epidemiological literature.”

“…stronger in male cohort members. r 4920 r for instance, individuals with better cognitive ability tend to smoke less and exercise more (Gottfredson, 2004), and these lifestyle factors may impact brain structure (e.g. [Almeida et al., 2011; Hillman et al., 2008]; note that such factors…”

“Better educated individuals may be more likely to recognize disease symptoms and to obtain medical care (Glied & Lleras-Muney, 2008; Gottfredson, 2004), and to enjoy other benefits of higher socioeconomic status, which may also account for the direct effect of educational attainment on…”

“…(McDaniel & Banks, 2010) and health and mortality (Arden, Gottfredson, & Miller, 2009; Arden, Gottfredson, Miller, & Pierce, 2009; Deary, 2008; Gottfredson, 2004) to brain volume (McDaniel, 2005) and understanding how sexual selection might have affected the development of cognitive ability…”

“Briefly, it has long been argued that g attains its importance because it reflects individual differences in the ability to successfully comprehend and function rationally in an increasingly cognitively complex world (Gottfredson, 1997, 2004; Hunt, 1995; Jensen, 1998).”

“Intelligence has been conceptualized as a fundamental cause for similar reasons (32).”

“This association may be causal and a number of mechanisms for this association have been proposed [5, 7].”