Is low blood pressure always healthy? Evidence of an inverse association between depressive symptoms and arterial blood pressure in a primary care sample

Background: Common mental health problems, such as anxiety and depression, have been related to the imbalance of the autonomous nervous system, also involved in blood pressure regulation. Low blood pressure readings have mainly been regarded as positive, but recent studies suggest low blood pressure is correlated with depression. The aim of the present research was to investigate the relationship between symptoms of anxiety and depression and blood pressure measures in a primary care sample. Method: We conducted a cross-sectional study that received the approval of the local Ethical Committee. All consecutive patients undergoing a GP consultation in a Northern Italy practice were evaluated, with the following exclusion criteria: age b40 or N80; use of antidepressants or antipsychotics medication; psychosis or major depression; previous stroke or heart attack; type I diabetes mellitus; obesity related to hereditary conditions; pregnancy. The psychometric assessment was done by HADS (Hospital Anxiety and Depression Scale). Arterial blood pressure was measured twice using a stethoscope and a sphygmomanometer at the right upper arm after 5 min of seated rest; the mean measure was considered. High Blood Pressure (BP) cut-offs: systolic BP ≥130 mm Hg and/or diastolic BP ≥ 85 mm Hg, according to IDF 2005 guidelines. The statistical multiple linear regression analysis was performed using STATA. Results: 209 subjects were enrolled in the study (125 women and 89 men). 122 subjects (58.1% of the whole sample) suffered from high blood pressure, and 98 of them (46.7%) followed an antihypertensive pharmacological therapy. A statistically significant inverse correlation between high diastolic BP and symptoms of depression at the HADS-D scale (β= −.28, p= .01) was found in the whole sample. The association was maintained in the male subsample, also after stratification by age, especially in the 40–60 years' group of patients (β=−.53, p =.04). On the contrary, no significant association was found between anxiety and BP measures. Conclusion: This study confirms an inverse association between high diastolic BP and depression at epidemiological level in an outpatients sample; longitudinal studies are needed in order to examine temporal occurrence and to explore the pathophysiology and the molecular mechanism at the basis of this association. Further researches should also investigate whether our results are generalizable to other populations.