THE WHITE COAT EFFECT IS ASSOCIATED WITH AN ENHANCED RESPONSE 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 HP (SBP) was recorded beat-to-beat with a Fi napres device during 3 periods of at least 5 minutes: 1) rest (alone, in lying position); 2) white coat (5 measurements of BP with 2 standar d mercury sphygmomanometer by the same physician); 3) mental stress (v ersion for computer of the Stroop Word Color Conflict Test). A Coarse- graining spectral analysis was performed to compute the power in the l ow frequency band (PLF: 0-0.150 Hz) and in the high frequency band (PH F: 0.150-0.500 Hz). SBP was 142 +/- 3.7 mmHg during the rest period an d increased significantly during the white coat (156.7 +/- 3.9 mmHg) a nd the mental stress (190.7 +/- 4.8 mmHg) periods. These rises of SBP levels were associated with a rise of PLF, significant only during men tal stress (11.3 +/- 1.4, 15.7 +/- 3.7, 17.2 +/- 2.4 mmHg(2)/Hz, durin g rest, white coat and mental stress periods, respectively). Moreover, a significant correlation (r = 0.76; p < 0.0001) was found between th e white coat effect (PAS ''white coat'' - PAS ''rest'') and the respon se to stress (PAS ''stress'' - PAS ''rest''). This work shows that whi te 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 effe ct may involve an activation of the sympathetic system.