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Conscientious children less likely to smoke as adults

Personality trait may help explain health inequality gap, say researchers

Caroline White

Tuesday, 24 March 2015

Conscientious kids are less likely to smoke in later life, indicates research* published online in the Journal of Epidemiology & Community Health. And this personality trait might help explain health inequalities, suggest the authors.

People from more disadvantaged backgrounds have lower life expectancy and more health problems than those in more affluent strata of society, and certain health behaviours, such as smoking, follow a similar pattern, suggesting they could be partly responsible for the health inequalities gap.

Recent evidence suggests that certain personality traits may be associated with health outcomes and health behaviours, echoing a similar social gradient seen in smoking and health outcomes.

In particular, conscientiousness, the tendency to be self-controlled, dutiful, reliable and goal oriented, has been linked to longer life expectancy and certain health behaviours. But it is not clear whether conscientiousness is a cause or consequence of social inequalities.

To gain a greater understanding of the influence of conscientiousness on smoking and its social gradient, the researchers assessed the relationship between the two over the life course.

Using data from the 1958 National Child Development Study, they looked at the extent to which two measures of conscientiousness—one assessed using a personality questionnaire at age 50 and one derived from three related items assessed at age 16 years—explained the social gradient of smoking at age 50.

They used a logistic regression model which took account of social class at birth, cognitive ability, attention and conduct problems at age 7, and educational qualifications attained across adulthood.

Childhood conscientiousness seemed to be a significant predictor of smoking at the age of 50 years 5% of the social gradient in prevalence of the habit after these influential factors had been taken into account.

“That childhood conscientiousness explained a small proportion of the social gradient of smoking at age 50—independent of educational attainment, childhood cognitive ability, attention and conduct problems, and childhood social class— suggests that childhood conscientiousness is not merely an indicator of social class or cognitive ability,” say the researchers.

Adult conscientiousness was a significant but lesser predictor than childhood conscientiousness of smoking behaviour at age 50, even after taking account of educational attainment at the age of 50, cognitive ability, attention and conduct problems at age 7, and social class at birth.

However, when conscientiousness in childhood was also factored in, the relationship between adult conscientiousness and smoking was no longer significant, suggesting that the protective effects of adult conscientiousness may arise during childhood.

“Importantly, childhood conscientiousness emerged as a stronger predictor of smoking than adult conscientiousness and statistically accounted for the association of conscientiousness measured at age 50 with smoking, suggesting that the personality trait conscientiousness is a predictor rather than a product of social differences in smoking,” write the researchers.

Other studies have shown that self-control in childhood is an important factor for health outcomes in adulthood, but there are likely to be other mechanisms involved in the protective effects of conscientiousness, such as compliance with treatment and preventive advice, which have not been examined, the researchers say.

“An important question for future research will be the investigation of specific mechanisms involved in the association between high conscientiousness in childhood with lower likelihood of smoking in adulthood,” they write.

They acknowledge that many participants in the National Child Development Study were lost to follow up over time, with smokers and those of lower social class and lower conscientiousness scores less likely to have completed the 50-year assessment.

And they point out that other factors, which could have had an influence on smoking behaviour, such as parental smoking and smoking-related medical issues, were not taken into account.

* Michael Pluess, Mel Bartley. Childhood conscientiousness predicts the social gradient of smoking in adulthood: a life course analysis. J Epidemiol Community Health 2015;69:330-338 doi:10.1136/jech-2014-204263

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