Shyness is a temperamental trait characterized by an anxious preoccupation with the self and heightened reactivity in social situations. This trait is moderately stable across the childhood to adulthood [1]. Shy children often express social withdrawal and internalizing problems (i.e., loneliness, anxiety and depressive symptoms), if they have experienced negative peer experiences, such as peer rejection and victimization [2-6]. In contrast, mutual and high-quality friendships [6, 7] as well as parenting styles characterized by high warmth and autonomy [4, 8-10] buffer against social withdrawal and internalizing problems among shy youth. While the link between shyness and later socioemotional problems is well-documented, little is known about physical health outcomes of shy children even though epidemiologic studies suggest that childhood social withdrawal/isolation, an outcome of childhood shyness, is an independent risk factor for increased cardiovascular disease (CVD) risk in adulthood [11-13]. Similarly, studies using animal models show that rodents and dogs with stable neophobic/inhibited traits have shorter lifespan, dampened immune response, and elevated glucocorticoid production [14-17]. Yet, no studies in humans have identified whether early temperamental shyness plays a role in increased CVD risk in adulthood and how temperamental shyness, peer and parental relationships shape the development of physiological systems linked to CVD risk across the lifespan to confer later health risks. This research proposal aims to address these knowledge gaps by considering a broad range of negative and positive peer-experiences in relation to CV risk factors measured from childhood to adulthood, and the potential role of child mental health within this relationship. Using the ASLPAC cohort, we will address the following questions:

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