Scimex: Conscientious seven-year-old kids are less likely to smoke later in
life, a UK study has reported, and the personality trait could help
explain why some health inequalities exist in the population. The
researchers found that childhood conscientiousness was a strong
predictor of smoking at the age of 50, and accounted for around five per
cent of the prevalence of the habit.
It is well known that people belonging to lower socio-economic groups
have lower life expectancy and more health problems than those who are
in higher groups, and certain health behaviours, such as smoking, follow
a similar pattern, suggesting they could be partly responsible for
health inequalities.
Recently, certain personality traits have been found to be associated
with health outcomes and health behaviours and to follow a similar
social gradient to smoking and health outcomes. In particular,
conscientiousness, the tendency to be self-controlled, dutiful, reliable
and achievement oriented, has been linked to longer life expectancy and
certain health behaviours. However, it is has not been 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 of the two over the life course. Using data from the 1958
National Child Development Study, they examined 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 was found to be a significant predictor of
smoking at 50 years explaining 5% of the social gradient in prevalence
of the habit after these influencing 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 authors.
Adult conscientiousness was a significant but lesser predictor than
childhood conscientiousness of smoking behaviour at age 50, even after
controlling for educational attainment at age 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 became
non-significant, suggesting that protective effects of adult
conscientiousness may in fact arise during childhood.
The authors say: "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."
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 authors 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 say.
The authors acknowledge that the study has several limitations,
including that many participants in the National Child Development Study
were lost to follow up over time, with smokers and those of lower
social status and lower conscientiousness scores less likely to have
completed the 50-year assessment. In addition, 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.