The Role of early-life psychological factors in the development of chronic disease: a longitudinal analysis applied to the onset of cancer, diabetes, and asthma in mid-life.

Abstract

Background: There is increasing evidence that psychological factors such as stress and depression might have an influence in the onset of many physical illnesses, but less is known about their effect from early life. This study is an epidemiological life-course analysis to test: (1) the hypotheses that early-life psychological factors are linked to later development of chronic disease (cancer, diabetes, and asthma) in mid-life, (2) whether such associations can be explained by pre-existing confounding factors, and (3) whether such links are mediated by other biological, behavioural, social, and cognitive factors. Methods: The data were from two ongoing prospective longitudinal studies following the lives of about 17,000 people born in Great Britain in one particular week in 1958 and 1970. Outcomes included diagnosis of cancer, asthma, and diabetes up to the year 2000. Psychological measures taken from ages 5 to 16 years were the main predictors. Associations were examined using discrete-time survival analysis and structural equation models, adjusting for potential confounders and mediators. Results: In the 1958 cohort, a standard deviation increase in the scores of conduct problems at ages 11 and 16 years, indicating severe behavioural problems, was associated with 2 to 34% increase in the odds of being diagnosed with cervical or all cancers after adjusting for childhood confounders. These effects were completely mediated by adulthood psychological distress and health behaviours. Only the teacher-reported behavioural problems significantly predicted the risk of diabetes after adjusting for family history of diabetes and sex (odds ratios of 1.05 to 1.08, p<O.Ol). These associations were partly mediated by mid-life psychological distress and adiposity. Significant associations were observed between most of the childhood psychological factors and adult-onset asthma even after adjusting for possible confounders and mediators. Conclusions: Childhood problem behaviours may predict chronic disease risk over the life-course either directly or mediated through adulthood factors. A consistent pathway among the disease groups was through adulthood psychological distress. Such continuities from childhood to adulthood psychological distress to the disease may be explained by the substantial biological plausibility of the association between psychological factors and physical health, primarily via alteration of the endocrine and the immune systems. The importance of promoting positive emotional and behavioural development in early life is stressed.