What happens to children's mental health when we treat their parent's depression? We have no idea. An empty systematic review.

Background: Parent depression is a well-established prospective risk factor for adverse offspring mental health. Multiple lines of evidence suggest that improvements in parent depression predicts improved offspring mental health. However, no systematic review has examined the impact on offspring of psychological treatment of purely parent depression after the postnatal period.

Aims: To systematically review the literature of randomised controlled trials examining the impact on offspring mental health outcomes of psychological interventions for parental depression after the postnatal period.

Method: We pre-registered our systematic review on PROSPERO (CRD42023408953), and searched the METAPSY database in April 2023 and October 2024, for randomised controlled trials of psychological interventions for adults with depression, which also included a child mental health or wellbeing outcome. We double screened 938 studies for inclusion using the 'Paper in a Day' approach. All included studies would be rated using the Cochrane Risk of Bias tool.

Results: We found no studies that met our inclusion criteria.

Conclusions: Robust research into psychological therapy for depression in adults outside the postnatal period has failed to consider the potential benefits for the children of those adults. This is a missed clinical opportunity to evaluate the potential preventive benefits for those children at risk of adverse psychological outcomes, and a missed scientific opportunity to test mechanisms of intergenerational transmission of risk for psychopathology. Seizing the clinical and scientific opportunities would require adult-focused mental health researchers to make inexpensive additions of child mental health outcomes measures to their evaluation projects.