The independent association between salivary alpha-amylase activity and arterial stiffness in Japanese men and women: the Toon Health Study

Psychological stress is considered to be a potential contributor in the development of arterial stiffness. However, an independent association between arterial stiffness and biological markers of stress has not yet been established. We examined the independent association between salivary alpha-amylase (sAA) activity and arterial stiffness, not mediated by cardiometabolic disease associated with arterial stiffness, in a sample of healthy Japanese men and women. Participants (992 in total, 296 men and 696 women aged 30-79 years) had neither previous cardiovascular events or stroke, nor coexisting hypertension, diabetes, or dyslipidemia. Arterial stiffness was measured by the cardio-ankle vascular index (CAVI), and increased CAVI was defined as a CAVI value of 9 or higher. A saliva sample was collected in the morning and sAA was measured with a commercial assay kit. Higher sAA activity was positively associated with greater arterial stiffness particularly among women (beta = 0.070; 95% CI = 0.014-0.126; p = 0.01), and not across all participants (beta = 0.042; 95% CI = -0.005-0.089; p = 0.08) and in men (beta = -0.005; 95% CI = -0.097-0.087; p = 0.91). The association was strongest in the group of women aged 60 years and older (beta = 0.121; 95% CI = 0.018-0.224; p = 0.02). Although the association between sAA and increased CAVI (CAVI >= 9) was not significant in all and sex subgroups, odds ratios (OR) for CAVI >= 7 were significantly high in all participants (OR = 1.25; 95% CI = 1.03-1.53) and women (OR = 1.43; 95% CI = 1.12-1.82). Elevation of sAA was associated with an increase in arterial stiffness, particularly for women aged 60 years or older.