Life-course pathways to psychological distress: a cohort study

OBJECTIVES Early life factors, like intelligence and socioeconomic status (SES), are associated with health outcomes in adulthood. Fitting comprehensive life-course models, we tested (1) the effect of childhood intelligence and SES, education and adulthood SES on psychological distress at midlife, and (2) compared alternative measurement specifications (reflective and formative) of SES. DESIGN Prospective cohort study (the Aberdeen Children of the 1950s). SETTING Aberdeen, Scotland. PARTICIPANTS 12 500 live-births (6282 boys) between 1950 and 1956, who were followed up in the years 2001-2003 at age 46-51 with a postal questionnaire achieving a response rate of 64% (7183). OUTCOME MEASURES Psychological distress at age 46-51 (questionnaire). RESULTS Childhood intelligence and SES and education had indirect effects on psychological distress at midlife, mediated by adult SES. Adult SES was the only variable to have a significant direct effect on psychological distress at midlife; the effect was stronger in men than in women. Alternative measurement specifications of SES (reflective and formative) resulted in greatly different model parameters and fits. CONCLUSIONS Even though formative operationalisations of SES are theoretically appropriate, SES is better specified as reflective than as a formative latent variable in the context of life-course modelling.