Date of this Version
Sullivan, G. A. (2021). Individual differences in social responsiveness, social experiences, and oxytocin system genetic variation in depression symptom severity.
Social experiences including discrimination, low social support, and interpersonal conflict are reliable predictors of depression symptom severity (Costello, 1982; Monroe, Rohde, Seeley, & Lewinsohn, 1999; Phifer & Murrell, 1986). However, individual differences may buffer against or exacerbate risk (Pluess & Belsky, 2015). A more holistic and dimensional approach, in line with modern perspectives on mental health (Kircanski, LeMoult, Ordaz, & Gotlib, 2017), requires an investigation of individual differences that moderate associations of positive and negative social experiences with depression symptom severity. This dissertation assesses relative contributions of social experiences (low social support, discrimination, childhood trauma, and sexual objectification) to variation in depression symptom severity and how social responsiveness traits (rejection sensitivity, need to belong, self-monitoring, dispositional empathy, alexithymia, and a Social Responsiveness latent variable) moderate these associations in a sample of 1,128 college students. It also includes a systematic review of the role of oxytocin system genetic variation in depression. Evidence from the review informed creation of a polygenic score of variation associated with higher oxytocin neurotransmission which was tested in association with depression symptom severity and social responsiveness traits in a sample of 1,022 college students. Discrimination and perceived social support were most strongly associated with depression symptom severity and these associations were moderated by rejection sensitivity, alexithymia, and a Social Responsiveness latent variable. Oxytocin system genetic variation was not associated with depression symptom severity or social responsiveness traits. The polygenic score moderated an association between net social experiences and depression symptom severity, but this effect did not survive Bonferroni correction or tests for moderation of individual social experiences. Results strengthen and expand upon theories of resilience and susceptibility and may inform individualized treatment for depression symptoms, including interventions focused on social cognition (Masi, Chen, Hawkley, & Cacioppo, 2011) and healing from discrimination (Comas-Díaz, 2016). Results align with evidence suggesting genetic variation in the oxytocin system is not robustly associated with depression symptom severity (Tollenaar, Molendijk, Penninx, Milaneschi, & Antypa, 2017).
Advisor: Scott F. Stoltenberg