Background: High uric acid (UA) is associated with hypertension and cardiovascular disease (CVD), both of which occur disproportionately among African Americans. High UA also predicts greater blood pressure reactivity responses to acute social stress. However, whether UA itself shows reactivity in response to stress is unknown. We evaluated salivary uric acid (sUA) and blood pressure reactivity in response to acute social stress. Healthy African Americans (N = 103; 32% male; M age = 31.36 years), completed the Trier Social Stress Test. sUA and blood pressure measurements were taken before, during and after the stressor task. sUA showed significant reactivity and recovery, especially among older African Americans. Total sUA activation was also associated with systolic and diastolic blood pressure total activation. Findings illuminate that acute stress may be a way in which UA is implicated in hypertension and CVD, suggesting a critical need to explore UA reactivity as a novel parameter of the acute stress response.
High levels of uric acid are associated with greater risk of stress-related cardiovascular illnesses that occur disproportionately among African Americans. Whether hyperuricemia affects biological response to acute stress remains largely unknown, suggesting a need to clarify this potential connection. The current study examined how salivary uric acid (sUA) is associated with resting and reactive blood pressure – two robust predictors of hypertension and related cardiovascular disease and disparity. Healthy African Americans (N = 107; 32% male; M age = 31.74 years), completed the Trier Social Stress Test to induce social-evaluative stress. Systolic and diastolic blood pressure readings were recorded before, during, and after the task to assess resting and reactive change in blood pressure. Participants also provided a saliva sample at baseline that was assayed for sUA. At rest, and controlling for age, sUA was modestly associated with higher systolic (r = .201, p = .044), but not diastolic (r = .100, p = .319) blood pressure. In response to the stressor task, and once again controlling for age, sUA was also associated with higher total activation of both systolic (r = .219, p = .025) and diastolic blood pressure (r = .198, p < .044). A subsequent moderation analysis showed that associations between sUA and BP measures were significant for females, but not for males. Findings suggest that uric acid may be implicated in hypertension and cardiovascular health disparities through associations with elevated blood pressure responses to acute social stress, and that low levels of uric acid might be protective, particularly for females.
Background: Uric acid (UA) is associated with cardiovascular and metabolic disorders, as well as a wide range of other health conditions and behaviors. A non-invasive measure of UA would be particularly useful in biobehavioral health and clinical research. We examined the validity and stability of salivary UA as a noninvasive measure of serum UA.
Methods: To interrogate the validity of salivary UA as a marker of systemic UA, we measured UA levels in blood and saliva samples collected on a single occasion from healthy adults (n=99; age 18-36 years, 54% male). We examined the serum-saliva correlation for UA and associations between salivary UA and inflammatory markers in serum and saliva, and with self-reported oral health indices. We also tested whether associations of UA with adiponectin and C-reactive protein, circulating markers of cardiovascular health, are evident in saliva. Using longitudinal data from young adults (n=182; age 18-31 years; 46% male) we examined salivary UA stability. Correlations and latent state-trait modeling examined the stability of salivary UA levels; the percent of variance in salivary UA estimates attributable to trait and state-components; and associations of the salivary UA trait component with body mass index (BMI) and sex.
Results: We found a strong positive association between salivary and serum UA. Neither the direction nor the magnitude of this association was related to total protein in saliva, blood leakage into oral fluid, proinflammatory cytokines, or biobehavioral indices of poor oral health. Results also revealed robust inverse associations between UA and adiponectin in both serum and saliva. Salivary UA levels were also highly correlated within and between assessment points 3 hours as well as 2 months apart. Advanced statistical modeling showed the majority (62-66%) of the variance in salivary UA could be attributed to a latent trait component suggesting relative stability in salivary UA levels. Furthermore, BMI and sex were associated with the stable trait-like component of salivary UA.
Conclusions: The findings demonstrate strong measurement validity and stability when UA is measured in saliva, and provide evidence supporting salivary UA as a robust indicator of systemic UA activity. These finding suggest that salivary UA could serve as a biomarker for a wide range of potential conditions and disease states.
Uric acid is a naturally occurring, endogenous compound that impacts mental health. In particular, uric acid levels are associated with emotion-related psychopathology (e.g., anxiety and depression). Therefore, understanding uric acid’s impact on the brain would provide valuable new knowledge regarding neural mechanisms that mediate the relationship between uric acid and mental health. Brain regions including the prefrontal cortex, amygdala, and hippocampus underlie stress reactivity and emotion regulation. Thus, uric acid may impact emotion by modifying the function of these brain regions. The present study used functional magnetic resonance imaging (fMRI) during a psychosocial stress task to investigate the relationship between baseline uric acid levels (in saliva) and brain function. Results demonstrate that activity within the bilateral hippocampal complex varied with uric acid concentrations. Specifically, activity within the hippocampus and surrounding cortex increased as a function of uric acid level. The current findings suggest that uric acid levels modulate stress-related hippocampal activity. Given that the hippocampus has been implicated in emotion regulation during psychosocial stress, the present findings offer a potential mechanism by which uric acid impacts mental health.