I was reading For Her Own Good, which annoys me sometimes with overromanticizing women's healing, etc. I was interested in the bit on neurasthenia, because I wondered if that connected with the common problem of chronic fatigue in modern America. The thesis of that section seems to be that women adopted illness roles as a reaction to domestic expectations, and only upper class women became ill in such a way. I felt a tug at my memory- something about neurasthenia and China. I couldn't find the book that I was looking for, so you'll have to do with this interesting, but poorly formatted article on how neurasthenia is distinct from depression as a diagnostic category.
Checking around, it seems that ethnic minorities seem to have equal prevalence of chronic fatigue syndromes[warning, pdf link, and one study[although you can't depend on just one study for the whole picture of a disease] notes that among different races and socioeconomic classes they do not find any significant differences in prevalence.
What an interesting puzzle! But I probably should go and lay down now.
Related: heh, special healing hat.