Parenting interventions reduce mental health problems in children. Considerable research has explored the psychosocial pathways of treatment effects; however, less is known about the biological mechanisms of intervention outcomes. Thus, the over-arching goal of the current work was to contribute to the literature on the biological influences of parenting-based treatment outcomes, using a candidate gene approach. Through a meta-analysis (Study 1) and intervention study (Study 2) the present work examined the effects of the Dopamine Receptor D4 (DRD4) gene and attachment on a child’s response to parenting-based interventions, with a focus on adolescent samples. Study 1: A meta-analysis and systematic review were performed to provide an overview of the literature. Articles were retrieved from PsycINFO, Medline and Proquest databases, relevant journals, and a manual search. In total, k = 27 articles were obtained, with k = 12 representing unique samples, and data available from k = 10 studies. Articles were coded to obtain effect size data and study characteristics. High inter-rater reliability was achieved. Overall, results replicated previous findings of gene-by-intervention effects. The combined effect size of the intervention in the genetically “susceptible” group was statistically significant and yielded a small effect (d = -0.34), while the “non-genetically susceptible” group’s results were not statistically significant and yielded a negligible effect (d = -0.01). Sub-analyses on the DRD4 gene and attachment-based interventions followed similar patterns. There was a paucity of research on adolescent samples, and thus a qualitative literature review was performed. Study 2: A study on a sub-sample (N = 341) from the provincial evaluation of the Connect Parent Group was performed on the role of DRD4 and attachment on youth outcomes. Demographic information, attachment ratings, and measures of psychopathology were collected from youth self-report at pre-, mid-, post-treatment and at 6 month follow-up. Primary analyses were conducted using structural equation modeling to test a mediated moderation model. Partial support for the hypotheses was observed. This work was one of the first to assess the genetic moderation of parenting-based intervention outcomes in adolescents. Clinical implications for tailoring parenting interventions are discussed.
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Thesis advisor: Moretti, Marlene
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