Cognitive and autonomic dysfunction measures in normal controls, white coat and borderline hypertension
1 Division of Medical Sciences, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Trust, (Queen Elizabeth), Birmingham, (B15 2TH), UK
2 Department of Internal Medicine, Faculty of Medicine and Health Sciences, UAE University, (Maqam), Al-Ain, (P. O. Box: 17666), United Arab Emirates
BMC Cardiovascular Disorders 2011, 11:3 doi:10.1186/1471-2261-11-3Published: 11 January 2011
White coat hypertension (WCHT) is a significant clinical condition with haemodynamic differences and presence of functional changes. We aim to compare cognitive and autonomic dysfunction variables (heart rate variability) between subjects with normal blood pressure (controls), WCHT, and borderline hypertension (BLH).
We performed a cross-sectional study in a cohort of 69 subjects (mean age ± SD; 38.2 ±10.8 years) comprising comparable number of normal controls, WCHT, and BLH. We measured clinic and 24-hour ambulatory blood pressure monitoring (ABPM), cognitive function parameters, and heart rate variability (HRV). All subjects underwent 24-hour ambulatory electrocardiography monitoring which was analyzed for HRV measurements. We performed a routine echocardiography (ECHO) for all subjects.
Multiple comparison between the three groups revealed significant (p < 0.04) differences in mean day-time ABPM (systolic and diastolic). In the state anxiety inventory (SAI), both subjects with WCHT and BLH had significantly (p < 0.006) higher anxiety levels than the control group. In memory tasks WCHT subjects scored significantly (p < 0.004) lower in comparison with the other two groups. WCHT significantly (p < 0.001) performed less in memory tests, whereas BLH subjects had significantly (p < 0.001) lower reaction time. We found a significant (p < 0.05) difference in the 24-hour RMSSD and SDNN between the three groups. There was significant correlation between 24-hour RMSSD and computer CANTAB scores. The Echocardiography assessment revealed no significant differences in LV mass indices and diastolic function.
WCHT and BLH subjects showed lower cognitive performance and higher levels of anxiety when compared to controls. Autonomic function reflected by HRV indices was lower in WCHT and BLH in contrast to control, though not significantly. Our results suggest that WCHT may not be a benign condition as it may contribute to the overall risk for cardiovascular disease and LV damage. Longitudinal studies of patients with WCHT should clarify the transient, persistent or the progressive nature of this condition.