Cranial Blood Flow Differences Between Populations?

A provisionally published paper in BMC Research Notes by Farhoudi et al uses transcranial Doppler to investigate flow rates in major cerebral arteries. They found that the averages for their sample from northwest Iran were higher than previously described norms.

The numbers are presented as-is with no p-value, so caution is in order in thinking these are necessarily real (though Farhoudi et al don't make any claims beyond presenting the numbers.) What is immediately interesting is whether there are real population differences and what that means for investigative methods like fMRI studies. There's also the question of whether there are clinical correlations (different stroke rates and outcomes in some populations?) or even behavioral/cognitive connections - though for that last question I'll hope that Razib Khan picks up the story.