Cognition, Mental Health and Quality of Life in Young Women: Relationships with Obesity, Nutrition and Physical Activity

Abstract

Key nutrients such as iron and omega-3 polyunsaturated fatty acids (n-3 PUFA), physical activity (PA) and obesity may individually or conjointly influence cognition and mental health in young women. Iron deficiency, low n-3 PUFA intake (reflective of the Omega-3 Index, O3I), inadequate PA, obesity and a higher risk of mental health issues have previously been identified in this cohort. This thesis aimed to investigate these factors in young (18-35 y) Australian women and is based on a meta-analysis of existing research and the Food Mood and Mind (FMM) study. This cross-sectional study was conducted in a convenience sample of healthy, women (n=299) of normal (NW, n=157) or obese weight (OB, n=142). Cognitive performance was assessed via a validated electronic platform (IntegNeuro™) across five domains: impulsivity, attention, information processing, memory and executive function. Iron and O3I status, inflammation, PA, depression and anxiety symptoms, and quality of life (QOL) were assessed. Meta-analysis (Chapter 2) examining the relationship between cognitive function and overweight/obesity in adults showed a significant yet small effect for executive function reflective of reduced performance compared to the normal weight group. Chapter 3, 4 and 5 present the results from the FFM cohort with a focus on the association between: cognitive function, ID and O3I status; cognitive function and obesity; and mental health and QOL. Results of the FFM study indicate that IDA, low O3I status and obesity are associated with decreased cognitive function. Obesity per se was also shown to be an independent risk factor for depression and anxiety symptoms and lower QOL markers. Importantly, the FMM study found cognitive performance and results for mental health and QOL were within the normal range (± 1 z-score). Potentially, the small reductions observed in cognition and poorer mental health may progress with prolonged exposure to sub-optimal nutrient levels and obesity.