Purpose: To investigate whether low parental socioeconomic position (SEP) at birth is associated only with early-onset depressive symptoms in offspring.
Methods: This prospective cohort study used data on 9193 individuals (4768 females, 4425 males) from the Avon Longitudinal Study of Parents and Children. Depressive symptoms during three age periods (10-12, 12-16, 16-20 years) were assessed using the Short Mood and Feelings Questionnaire, and ICD-10 depression at age 18 was assessed using the Clinical Interview Schedule-Revised.
Results: Low SEP was associated with increased incidence rates of depressive symptoms in all age periods, with indicators of low standard of living showing the strongest associations. For instance, incidence rate ratios for material hardship were 1.75 (95% CI [1.42-2.15]) at 10-12 years, 1.36 (1.16-1.61) at 12-16 years and 1.39 (1.21-1.59) at 16-20 years. Low SEP was also associated with increased odds of ICD-10 depression at 18 years, ranging from OR = 1.20 (95% CI [0.94-1.52]) for manual social class to 1.74 (1.35-2.24) for material hardship.
Conclusions: There was no evidence that depressive symptoms can be "subtyped" by the age of onset, because the association with low SEP was evident for early- and later-onset symptoms. If socioeconomic inequalities in early life have long-term adverse impacts on mental health, policies addressing these inequalities could benefit the mental health of the population.
Keywords: ALSPAC; Cohort study; Depression; Depressive symptoms; Socioeconomic position.