Bipolar disorder and related mood states are not associated with endothelial function of small arteries in adults without heart disease

Background: Individuals with bipolar disorder are at increased risk for adverse cardiovascular disease (CVD) events. This study aimed to assess endothelial function and wave reflection, a risk factor for CVD, as measured by finger plethysmography in bipolar disorder to investigate whether CVD risk was higher in bipolar disorder and altered during acute mood episodes. We hypothesized that EndoPAT would detect a lower reactive hyperemia index (RHI) and higher augmentation index (AIX) in individuals with bipolar disorder compared with controls. Second, we predicted lower RHI and higher AIX during acute mood episodes. Methods: Reactive hyperemia index and augmentation index, measures of microvascular endothelial function and arterial pressure wave reflection respectively, were assessed using the EndoPAT 2000 device in a sample of 56 participants with a DSM-IV diagnosis of bipolar I disorder with 82 measures spanning different mood states (mania, depression, euthymia) and cross-sectionally in 26 healthy controls. Results: RHI and AIX were not different between adults with and without bipolar disorder (mean age 40.3 vs. 41.2 years; RHI: 2.04 +/- 0.67 vs. 2.05 +/- 0.51; AIX@75 (AIX adjusted for heart rate of 75): 1.4 +/- 19.7 vs. 0.8 +/- 22.4). When modeled in linear mixed models with a random intercept (to account for repeated observations of persons with bipolar disorder) and adjusting for age and sex, there were no significant differences between those with bipolar disorder and controls (p = 0.89 for RHI; p = 0.85 for AIX@75). Conclusions: Microvascular endothelial function and wave reflection estimated by finger plethysmography were unable to detect differences between adults with and without bipolar disorder or changes with mood states. Future research is necessary to identify more proximal and sensitive, yet relevant, biomarkers of abnormal mood-related influences on CVD risk or must target higher risk samples.