Research Article Brain Oscillations Elicited by the Cold Pressor Test: A Putative Index of Untreated Essential Hypertension Christos Papageorgiou, 1 Efstathios Manios, 1 Eleftheria Tsaltas, 2 Eleni Koroboki, 1 Maria Alevizaki, 1 Elias Angelopoulos, 2,3 Meletios-Athanasios Dimopoulos, 1 Charalabos Papageorgiou, 2,3 and Nikolaos Zakopoulos 1 1 Department of Clinical Terapeutics, National and Kapodistrian University of Athens, Medical School, Athens, Greece 2 1st Department of Psychiatry, National and Kapodistrian University of Athens, Medical School, “Eginition” Hospital, 115 28 Athens, Greece 3 University Mental Health Research Institute (UMHRI), Athens, Greece Correspondence should be addressed to Christos Papageorgiou; chrispapageorgio@gmail.com Received 18 December 2016; Accepted 10 April 2017; Published 9 May 2017 Academic Editor: Tomohiro Katsuya Copyright © 2017 Christos Papageorgiou et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective. Essential hypertension is associated with reduced pain sensitivity of unclear aetiology. Tis study explores this issue using the Cold Pressor Test (CPT), a reliable pain/stress model, comparing CPT-related EEG activity in frst episode hypertensives and controls. Method. 22 untreated hypertensives and 18 matched normotensives underwent 24-hour ambulatory blood pressure monitoring (ABPM). EEG recordings were taken before, during, and afer CPT exposure. Results. Signifcant group diferences in CPT-induced EEG oscillations were covaried with the most robust cardiovascular diferentiators by means of a Canonical Analysis. Positive correlations were noted between ABPM variables and Delta (1–4Hz) oscillations during the tolerance phase; in high- alpha (10–12 Hz) oscillations during the stress unit and posttest phase; and in low-alpha (8–10 Hz) oscillations during CPT phases overall. Negative correlations were found between ABPM variables and Beta2 oscillations (16.5–20Hz) during the posttest phase and Gamma (28.5–45 Hz) oscillations during the CPT phases overall. Tese relationships were localised at several sites across the cerebral hemispheres with predominance in the right hemisphere and lef frontal lobe. Conclusions. Tese fndings provide a starting point for increasing our understanding of the complex relationships between cerebral activation and cardiovascular functioning involved in regulating blood pressure changes. 1. Introduction Hypertension is a leading risk factor for cardiovascular disease and a major contributor to healthcare costs worldwide [1]. Given that autonomic nervous system (ANS) activity modulates transient changes in cardiovascular function, autonomic dysfunction has been implicated in the pathogen- esis of essential hypertension (EH) [2]. Increased sympathetic activity [3] combined with parasympathetic inhibition may contribute to increased cardiac activity and/or peripheral vascular resistance and thereby to the early development of hypertension [4], although patients with borderline to mild hypertension ofen show normal vascular resistance at rest. Te central nervous system (CNS) has also been impli- cated in the aetiology and maintenance of some forms of EH. Te CNS is a target of the disease which, if untreated, progresses to blood pressure (BP) levels threatening the integrity of cerebral vessels, potentially inducing stroke [5]. Considerable evidence supports the connection between pain perception and BP regulation. It has been proposed that acute BP increases may reduce pain, thus establishing hypertension through instrumental learning [6]. Hypoalgesia has been noted in animals and humans with high BP [7], but the issue of whether it precedes or follows hypertension remains equivocal. Hindawi International Journal of Hypertension Volume 2017, Article ID 7247514, 17 pages https://doi.org/10.1155/2017/7247514