Methods in Neuroepidemiology Autonomic Nervous System Activity and Decline as Prognostic Indicators of Cardiovascular and Cerebrovascular Events: The 'PROOF' Study Study Design and Population Sample. Associations with Sleep-Related Breathing Disorders: The 'SYNAPSE' Study

Background: Transversal studies have underlined the association between the decline in autonomic nervous system (ANS) activity and all-cause mortality. However, the predictive value of ANS has never been prospectively assessed in a general population-based cohort. Method: The PROOF (PROgnostic indicator OF cardiovascular and cerebrovascular events) cohort study was designed to prospectively assess the predictive value of ANS activity level in the general population, with regard to cardiovascular and cerebrovascular events, and death. This predictive power will be compared with the usual and newly discovered risk factors for the purposes of developing a risk model. Results: A prospective cohort of elderly subjects aged 65 years upon study entry were recruited from the electoral list of the city of Saint-Etienne, France. Three initial 2-year examination programs were scheduled for 7 years (2001–2007), followed by late events monitoring. At each examination, ANS activity was assessed along with clinical and biological cardiovascular risk factors, brain MRI, neuropsychological evaluation, physical activity profile, and sleep-related breathing disorders. The main study outcomes are stroke, myocardial infarction and death from any cause. A cohort consisting of 1,011 subjects aged 65.6 (0.8) years was constituted. Conclusion: Despite other selective characteristics, the associations between ANS activity and events will be applicable to other populations.