Longitudinal effects of parent-child relationship quality on adolescent non-suicidal self-injury: the role of serotonergic multilocus genetic variation.

The present study examined the impact of serotonergic multilocus genetic variation, parent-child relationship quality and gender on the developmental trajectory of adolescent non-suicidal self-injury (NSSI). A sample of 552 first-year junior high school students from Hunan Province, China, participated in a three-wave longitudinal study. The study included detailed questionnaires and genetic sampling, conducted over a period of one and a half years. We hypothesize that parent-child relationship quality and serotonergic multilocus genetic profile score (MGPS) interact to influence adolescent NSSI trajectories, with possible gender differences. Using latent growth curve modeling (LGCM), the results revealed a linear decrease in NSSI over time, with parent-child relationship quality significantly predicting initial NSSI levels. The interaction between serotonergic MGPS and parent-child relationship quality predicted the intercept but not the growth rate of NSSI. There were also gender differences, such that female adolescents were more vulnerable to the combined effects of parent-child relationship quality and genetic factors, patterns that emerged for both initial NSSI intercept and slope. These results highlight the pivotal role of genetic and environmental factors, particularly parent-child relationship quality, in adolescent mental health. This work suggests that future interventions may be designed to strengthen parent-child relationships and tailored to genetic risks and gender-specific vulnerabilities.