The psychoneuroimmunology of women experiencing stressful life events: testing the oxidative model.

Abstract

It has been acknowledged that psychological stress can impact on one’s health. A definitive link between psychological state, immune suppression, and disease has yet to be established. A possible mechanism has been termed The Oxidative Model. This refers to the oxidative imbalance of cells associated with antioxidant status and psychological distress. The aim of this dissertation was to use this theoretical model to establish an evidence basis for future interventions in vulnerable populations. For cancer patients the post-treatment period has been identified as psychologically challenging. In addition bio-psycho-immunological models remain underexplored in post-treatment breast cancer samples to date. Two longitudinal studies were employed. The first, an observational study of a sample of women (N=17) concluding treatment (chemotherapy and/or radiotherapy) for early stage (I-III) breast cancer at the Royal Adelaide Hospital, South Australia. The second study tested the benefits of antioxidants during prolonged stress using an 8-week RCT. A sample of general population women (N=60) reporting mild to severe psychological distress was recruited. Psychological parameters measured included Psychological Distress, Defense Styles, Loneliness, Anger Expression, Psychological Adjustment, the Impact of Events Scale (IES-R), and State-Trait Depression, Curiosity, Anxiety, and Anger. Biochemical parameters included 5’-ectonucleotidase (NT), homocysteine (HCY), tissue ascorbate (VIT C), c-reactive protein (CRP), cholesterol (CHOL), folate (FOLATE), Vitamin B12 (VIT B12), and inflammatory cytokines (IL-1 β, IL-5, IL-6, IFN-γ, TNF-α, TNF-β, and IL-10). Findings from study 1 indicated severe psychological distress was experienced for a subset of breast cancer patients post-treatment. Fluctuating levels of psychological distress, anger, anxiety, and curiosity were observed across the 20-weeks. A pro-oxidant state was evident during this period. Pro-inflammatory measures were low and relatively stable. Associations between psychological measures and biomarkers supported Oxidative Model relationships. The second study revealed improved pro-oxidant and pro-inflammatory biomarkers favoured the multivitamin supplemented group. Collectively both studies reveal the influence of demographic and health behaviours on bio-psycho-social measures central to the Oxidative Model propositions. This thesis brings out the case for exploring complementary interventions, like multivitamin use, in the post-treatment period for those patients experiencing distress.