BACKGROUND:
adolescence is an important period for mental health development, and socioeconomic conditions during this stage may have lasting effects. However, evidence on the long-term association between adolescent socioeconomic status and adult depressive symptoms has not been comprehensively synthesized for longitudinal studies.

METHODS:
a pre-registered systematic review and meta-analysis was conducted using four databases, informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Longitudinal population-based studies assessing parental socioeconomic indicators during adolescence and depressive symptoms in adulthood were included. Study quality was evaluated using the National Institutes of Health Study Quality Assessment Tools (NIH-QAT). Random-effects meta-analyses were performed for studies with comparable exposure and outcome measures.

RESULTS:
thirteen longitudinal studies from eleven cohorts were included. Overall study quality ranged from fair to good. Lower socioeconomic status during adolescence was associated with higher levels of depressive symptoms in adulthood across parental income and education. Pooled estimates indicated modest associations, with little evidence of between-study heterogeneity or sex-specific effects.

CONCLUSIONS:
findings suggest that socioeconomic disadvantage in adolescence is associated with higher levels of depressive symptoms later in life. Results support life course approaches to mental health inequalities and highlight adolescence as an important period for public health prevention efforts.