Abstract
BACKGROUND: Prior research has shown that inappropriate childhood nurturing experiences (low care and high overprotection), trait anxiety, and depressive rumination are risk factors for depression. However, no studies to date have analyzed the overall association between these factors and depressive symptoms. In the present study, we hypothesized that depressive rumination mediates the impacts of inappropriate childhood nurturing experiences on depressive symptoms, and that these mediating effects are moderated by trait anxiety, and tested these hypotheses in adult volunteers. METHODS: The subjects were adult volunteers who were investigated between April 2017 and April 2018. A self-report questionnaire on demographic data, childhood nurturing experiences, trait anxiety, depressive rumination, and depressive symptoms was distributed to conduct the survey, and written informed consent and valid responses were obtained from 585 subjects. Mediation and moderated-mediation analyses were performed by SPSS 28 and macro PROCESS 4.0 software. This study was approved by the Ethics Committee of Tokyo Medical University. RESULTS: Parental care showed a significant negative indirect effect on depressive symptoms via its effect on depressive rumination (p < 0.01), whereas parental overprotection showed the opposite effect (p < 0.01). Furthermore, the mediation effect of depressive rumination on depressive symptoms was increased by trait anxiety (p < 0.05). CONCLUSION: Our present study demonstrated that the main factor affecting depressive symptoms is inappropriate childhood nurturing experiences, which indirectly enhance depression by intensifying depressive rumination, and that depressive rumination and trait anxiety mutually reinforce each other to enhance depressive symptoms. These findings may be useful for the prevention of depressive symptoms. Large-scale prospective studies are needed to confirm the causal associations among these factors in the future.