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

ABSTRACT

BACKGROUND AND PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: The constellation suggests a greater initial mismatch between functionally increased metabolic demand of neurons and adjusted cerebral blood flow in Asians.