Summary: | The identification of biomarkers to predict risk and clinical outcomes beyond clinical observation in psychiatry is a key priority in contemporary mental health research. Individuals at elevated risk for mental disorders have been the focus of such efforts as they represent a potentially viable target group for early intervention and indicated prevention. Early intervention and indicated prevention efforts for individuals at ultrahigh risk (UHR) for psychosis might benefit from such biomarkers to enable better risk prediction and to discern who will benefit from treatment. Alterations in neuroendocrine, immune and oxidative stress markers as well as abnormalities in lipid biology are robust findings in biological psychiatry. On the other hand, mounting evidence suggests that First Nations people including the Aboriginal and/or Torres Strait Islander people of Australia have a higher risk for common and severe mental illness, most likely attributable to social and environmental health determinants. However the role of stress-related biomarkers in this context remains poorly understood. Consequently, the aims of this thesis were to examine (1) a multisystem biomarker index known as allostatic load in two high-risk populations and to (2) examine the role of lipid biology in these groups. The first part of this thesis explores the role of allostatic load (AL) and omega-3 (ω-3) polyunsaturated fatty acids (PUFA) in two clinical studies of patients with schizophrenia, first-episode psychosis and individuals at UHR for psychosis. The second part explores the role of AL and dietary ω-3 PUFA in a community-based study of Aboriginal and/or Torres Strait Islander people, who are at increased risk for mental ill-health according to recent national reports. The above aims are achieved through meta-analysis of existing studies of cortisol in psychotic disorders, secondary analysis of two clinical studies, and in a cross-sectional multi-site community-based study of Aboriginal and/or Torres Straight Islander adolescents and ...
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