Cerebral lesion correlates of sympathetic cardiovascular activation in multiple sclerosis.

Cardiovascular autonomic dysfunction is common in multiple sclerosis (MS) and contributes significantly to disability. We hypothesized that cerebral MS-lesions in specific areas of the central autonomic network might account for imbalance of the sympathetic and parasympathetic cardiovascular modulation. Therefore, we used voxel-based lesion symptom mapping (VLSM) to determine associations between cardiovascular autonomic dysfunction and cerebral MS-related lesion sites. In 74 MS-patients (mean age 37.0 ± 10.5 years), we recorded electrocardiographic RR-intervals and systolic and diastolic blood pressure. Using trigonometric regressive spectral analysis, we assessed low (0.04-0.15 Hz) and high (0.15-0.5 Hz) frequency RR-interval-and blood pressure-oscillations and determined parasympathetically mediated RR-interval-high-frequency modulation, mainly sympathetically mediated RR-interval-low-frequency modulation, sympathetically mediated blood pressure-low-frequency modulation, and the ratios of sympathetic and parasympathetic RR-interval-modulation as an index of sympathetic-parasympathetic balance. Cerebral MS-lesions were analyzed on imaging scans. We performed a VLSM-analysis correlating parameters of autonomic dysfunction with cerebral MS-lesion sites. The VLSM-analysis showed associations between increased RR-interval low-frequency/high-frequency ratios and lesions most prominently in the left insular, hippocampal, and right frontal inferior opercular region, and a smaller lesion cluster in the right middle cerebellar peduncle. Increased blood pressure-low-frequency powers were associated with lesions primarily in the right posterior parietal white matter and again left insular region. Our data indicate associations between a shift of cardiovascular sympathetic-parasympathetic balance toward increased sympathetic modulation and left insular and hippocampal lesions, areas of the central autonomic network. The VLSM-analysis further distinguished between right inferior fronto-opercular lesions disinhibiting cardiac sympathetic activation and right posterior parietal lesions increasing sympathetic blood pressure modulation.

Blood pressure-associated emotional dampening and risky behavior: Elevated resting blood pressure predicts risky simulated driving in women.

Elevated resting blood pressure (BP) is associated with dampened responses to emotionally meaningful stimuli. This BP-associated emotional dampening may also influence threat appraisal and, hence, motivation to avoid risk. The present study was designed to determine if resting BP is associated with risky driving behavior assessed in a high fidelity driving simulator. Fifty-one healthy women (n = 20) and men (n = 31) rested for BP determinations both before and after a simulated driving scenario in a DriveSafety automotive simulator with six visual channels, single-axis motion, and functioning controls and instrumentation. Resting systolic (SBP) and diastolic (DBP) BPs were obtained systematically with a calibrated GE Dinamap Pro V100. Risky driving was assessed by speed relative to the posted speed limit, and a speed-adjusted time to collision index of tailgating. Regression analyses indicated that sex interacted with resting BP, with significant associations between BP and risk in women, but not men. For example, risky driving in women was associated with higher resting DBP (p = .006), with similar but less reliable effects for resting SBP (p = .058). These results provide some partial, preliminary support for the notion that BP-associated emotional dampening may reduce threat appraisal and thereby decrease motivation for risk avoidance, but these effects are confined to women in this simulated driving scenario. Interacting central nervous system (CNS) mechanisms controlling BP and emotional responsivity may mediate the relationship between BP and risk-taking behavior. Relative expression of this relationship in women and men may depend on multiple psychosocial and physiological mechanisms. The association of higher BP with increased risk-taking behaviors may have relevance to the early pathogenesis of essential hypertension.