[Reactivity of "white coat" type is associated with reactivity to mental stress]

This study was aimed to compare the white coat effect and the response to a mental stress. 29 subjects, referred for high blood pressure (BP) were included. Systolic BP (SBP) was recorded beat-to-beat with a Finapres device during 3 periods of at least 5 minutes: 1) rest (alone, in lying position); 2) white coat (5 measurements of BP with a standard mercury sphygmomanometer by the same physician); 3) mental stress (version for computer of the Stroop Word Color Conflict Test). A Coarse-graining spectral analysis was performed to compute the power in the low frequency band (PLF: 0-0.150 Hz) and in the high frequency band (PHF: 0.150-0.500 Hz). SBP was 142 +/- 3.7 during the rest period and increased significantly during the white coat (156.7 +/- 3.9 mmHg) and the mental stress (190.7 +/- 4.8 mmHg) periods. These rises of SBP levels were associated with a rise of PLF, significant only during mental stress (11.3 +/- 1.4, 15.7 +/- 3.7, 17.2 +/- 2.4 mmHg2/Hz, during rest, white coat and mental stress periods, respectively). Moreover, a significant correlation (r = 0.76; p < 0.0001) was found between the white coat effect (PAS "white coat"-PAS "rest") and the response to stress (PAS "stress"-PAS "rest"). This work shows that white coat effect is not a specific response but may rather represent an increased reactivity to stress. As it is associated with an increased power in the LF band like the response to stress, this white coat effect may involve an activation of the sympathetic system.