STAYING HEALTHY AFTER CANCER: THE HIDDEN INFLUENCE OF SOCIAL NETWORKS

Background: Few rigorous empirical studies have used social network models to investigate changes to the relationships most important to cancer survivors and their effects on health. The objective of this dissertation was to longitudinally examine the associations between egocentric social network change over time and physical, physiological, and mental health among cancer survivors and older adults without a history of cancer. Method: The National Social Life Health and Aging Project (NSHAP) (2004-2011) is a nationally representative cohort of older adults aged 57 and older. Physical functioning was measured with the Activities of Daily Living Scale and inflammation was measured by C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and vascular endothelial growth factor (VEGF). Depressive symptoms were measured with the 11-item version of the Centers for Epidemiologic Studies Depression (CES-D) Scale. Multiple logistic and linear regression and structural equation modeling were used to assess the relationships of interest. Results: Older cancer survivors and older adults without cancer experienced similar social network changes over time. In the overall NSHAP sample, adding new network members was protective of functional decline [odds ratio (OR): 0.64, 95% confidence interval (CI): 0.41-0.99] and experiencing a change in the frequency of contact was positively associated with functional decline (OR: 1.92, 95% CI: 1.15- 3.20). CRP levels were significantly 26% lower among cancer survivors who added two network members compared to those who added no network members. Experiencing a change in the frequency of contact was associated with a 19% higher level of TNF-α. Social support was directly associated with depressive symptoms and did not vary by cancer status. No mediation effects between social support, inflammation, and depressive symptoms were observed in path models and latent variable models. Conclusion: Together these results suggest that when new relationships form or when stable relationships remain strong over time, their effects on health are positive. Alternatively, negative health effects may emerge when relationships become weaker over time. This study provides significant and timely information to develop effective interventions to improve quality of life for cancer survivors and older adults