Understanding bidirectional and transactional relations in parent and offspring mental health: Using COVID-19 pandemic data to gain insights.

Background: Bidirectional and transactional models propose that parents and children have the potential to influence each other's mental health over time. While bidirectional associations have been widely studied, transactional processes involving parent internalising, offspring internalising, and offspring externalising symptoms remain underexplored. The COVID-19 pandemic was associated with marked changes in parent and offspring mental health, providing an enhanced opportunity to examine these dynamics across developmental stages and gender. Methods: We examined four waves of survey data from the UK-based longitudinal COVID-19: Supporting Parents, Adolescents and Children during Epidemics (Co-SPACE) study collected between May 2020 and May 2021. Data from 2349 parent-child dyads (4-16-year-old children) were analysed using multi-group (for age and gender) random intercept cross-lagged panel modelling. Results: In the full sample, parent internalising symptoms significantly predicted increases in offspring internalising symptoms over time. Among primary school aged children (4-10 years), effects were parent-driven, with no evidence that changes in child symptoms predicted parent symptoms. In contrast, among secondary school aged children (11-16 years), we found bidirectional associations between parent internalising and offspring externalising symptoms, and some time-specific links with internalising symptoms. However, no sustained transactional loops (i.e., indirect effects forming a feedback cycle) were detected. Gender did not moderate any associations. Conclusion: These findings suggest that parent and offspring mental health symptoms may become more reciprocal as children grow older.