I'm always skeptical of claims that "X" disease/condition is found at the
same rate in different populations, because most research is done in Western
countries.  Thus, the rates of schizophrenia may be similar in the US,
Canada, Germany, France, Holland, England, etc. -- all of which share many
underlying cultural similarities and child-rearing practices.  But what
about the rates of schizophrenia in cultures like the Bambara of Mali (whom
I have worked with) or the Jivaro of the Amazon rainforest, or the Sambia of
Highland New Guinea.  No one has good data on those populations, where
children are breastfed and carried for the first years of their lives.
"Across a number of cultures" from Chris' post may mean a number of very
similar, western industrialized cultures.


Or you read something like "traditional societies have exceptionally low
rates of Down Syndrome" -- well, they do if you only look at who survives,
but not if you look at births.  Children with Down Syndrome rarely survive
infancy outside of western populations because of the lack of necessary
medical care.  It isn't that they aren't born.  Or if someone claimed that
women in Mali had low rates of breast cancer, I'd be skeptical from the
perspective that almost none of them have had mammograms or been examined by
a doctor.  They probably *do* have low rates of breast cancer because
everyone breastfeeds, but you'd have to do a study examining everyone to
prove that.

People with schizophrenia definitely have something messed up with their
brain chemistry -- it may be partly genetic, or it may have something to do
with lack of essential ingredients in the formula.  Or it may be a
combination of a bunch of things.  I'd waiting to get my hands on the
British Journal of Psychiatry article before I jump to any conclusions.

Katherine A. Dettwyler, Ph.D.
Associate Professor of Anthropology and Nutrition
Texas A&M University