Locus of control at age 10 years and health outcomes and behaviors at age 30 years: the 1970 British Cohort Study.

OBJECTIVE: To examine the relationship between locus of control at age 10 years and self-reported health outcomes (overweight, obesity, psychological distress, health, and hypertension) and health behaviors (smoking and physical activity) at age 30, controlling for sex, childhood IQ, educational attainment, earnings, and socioeconomic position.
METHODS: Participants were members of the 1970 British Cohort Study, a national birth cohort. At age 10, 11,563 children took tests to measure locus of control and IQ. At age 30, 7551 men and women (65%) were interviewed about their health and completed a questionnaire about psychiatric morbidity.
RESULTS: Men and women with a more internal locus of control score in childhood had a reduced risk of obesity (odds ratio, 95% CI, for a SD increase in locus of control, 0.86, 0.78-0.95), overweight (0.87, 0.82-0.93), fair or poor self-rated health (0.89, 0.81-0.97), and psychological distress (0.86, 0.76-0.95). Women with a more internal locus of control had a reduced risk of high blood pressure (0.84, 0.76-0.92). Associations between childhood IQ and risk of obesity and overweight were weakened by adjustment for internal locus of control.
CONCLUSION: Having a stronger sense of control over one's own life in childhood seems to be a protective factor for some aspects of health in adult life. Sense of control provides predictive power beyond contemporaneously assessed IQ and may partially mediate the association between higher IQ in childhood and later risk of obesity and overweight.