Andrew Shaner: UCLA VA Hospital

Variation in the age at onset of a multifactorial disease often reflects variation in cause. In this talk, I show a linear latitudinal gradient in the mean age at onset of schizophrenia in 13 northern-hemisphere cities, ranging from 25 years old in Cali, Columbia (at 4 degrees north) to 35 years old in Moscow, Russia (at 56 degrees north). This striking association has not been previously reported. I consider several explanations, including the effects of pathogen stress, natural selection, sexual selection, migration, life-history profiles, or some combination of these factors, and I propose a test of competing causal hypotheses.
http://bec.ucla.edu/papers/Shaner07.pdf