Brain stuff is influenced by genetic makeup as much as any other health condition. Many health conditions present with different effect or prevalence in different racial sub-populations or between the sexes.

It's meaningful to include race if it was a factor, because she's saying it was a predominant trait in the study populations on which the diagnostic criteria were originally built.

If you don't study an effect in different populations to determine the universality of your criteria, you could very well be under- or over-diagnosing persons from those groups.