Ethnic influences on neurovascular coupling: a pilot study in whites and Asians.

Abstract

An ethnic extraintracranial difference in atherosclerosis has been well reported, whereas the potential mechanism remains unclear. We aimed to investigate neurovascular coupling in healthy whites and Asians. Twenty volunteers of each ethnicity were recruited to perform a functional transcranial Doppler examination with standardized checkerboard patterns as visual stimulation (3 x 4, 6 x 8, and 12 x 16 checks subtending a visual field section of 18 degrees x 24 degrees , flicker rate 1 Hz). Hemodynamic responses in both posterior cerebral arteries were evaluated with a control system approach. The rate time, that is, the initial speed of flow velocity adaptation, was significantly lower in Asians leading to an approximately 2-second delayed hemodynamic adaptation. The other hemodynamic parameters and the dependency of hemodynamic responses in regard to the complexity degree of the stimulus were similar between groups. The constellation suggests a greater initial mismatch between functionally increased metabolic demand of neurons and adjusted cerebral blood flow in Asians.