Over the past decades, several authors have demonstrated a significant association between stress hormones and memory in healthy elderly. In parallel, recent evidences have revealed that exposure to environmental contaminants (EC) such as heavy metals, polychlorinated biphenyls (PCBs) and organochlorides, and also the oxidative stress are associated with age-related memory impairment. Some EC could interfere in the regulation of sexual steroid hormones. However, little is known about the influence of the EC in the glucocorticoids (stress hormone) and in the oxidativo stress biomarkers. Hence, the main goal of this study is to investigate the relationship between stress response and EC exposure and their association with cognitive performance and oxidative stress biomarkers in healthy elderly. Thus, 122 elderly who have been living in São Paulo metropolitan area, without cognitive impairment or neurological/psychiatric disorders will be evaluated. Saliva samples will be collected to verify diurnal cortisol cycle and also the cortisol concentration face and acute psychosocial stressor ("Trier Social Stress Test" - TSST). Besides, blood samples will be collected in order to analyze EC concentrations and oxidative stress biomarkers. It has been hypothesized that the cognitive performance variability in the elderly could be partially explained by the influence of EC exposure which may alter the stress response affecting the cognitive performance. Moreover, it has been propose that one of the mechanisms involved in this association between EC exposure, stress response and cognitive impairment is related to the increased levels of oxidative stress biomarkers. The current study could contribute to the understanding of healthy cognitive aging process and to drive studies about cognitive impairment aging. Besides this, the analysis about the impact of EC on stress response could set a stage for more complex models about the role of EC in the stress related disorders development.
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