Do older adults become more depressed with age in Taiwan? The role of social position and birth cohort

Background: Depression is one of the most commonly encountered mental health problems during older adulthood. This study examines differences in depressive symptom trajectories among older Taiwanese adults across two birth cohorts (1920-1924 and 1925-1929), and explores the relationships between socioeconomic position (SEP) variables and symptom trajectories. Methods: Data from the Taiwan Longitudinal Study on Aging (TLSA) collected between 1989 and 2003 were analysed. The nationally representative sample is composed of community-living adults (n = 2458) in Taiwan aged 60 years and above. Two distinct domains of depressive symptomatology, negative affect and lack of positive affect, assessed by the short form of the Center of Epidemiological Studies-Depression (CES-D) scale were used for all the analyses. Growth curve models were employed to assess the trajectories of depressive symptoms over time. Results: The relationship between ageing and depressive symptoms appeared linear with a minor curvilinear effect. The depressive symptoms in negative affect increased with age (mean linear growth rate = 0.26, p < 0.001) but levelled off (mean quadric growth rate = -0.01, p < 0.001), while the symptoms in lack of positive affect displayed an opposite trend. The effects of SEP variables also differed by cohort and outcome domain. Conclusions: Remaining active, living with family and having a high level of education are associated with positive affect later in life, while financial strain and poor health are strongly related to negative affect. These results underline the continued role that SEP plays in psychological adjustment over the course of one's life, independently of ageing.