Role of selenium and other trace elements in the geography of schizophrenia.

Medical geology is the application of trace element geography to epidemiology. This approach is used to compare the geographic distribution of selenium and other trace elements in soil and food with that of high schizophrenia rates in the United States and other countries. Since the comparison is most statistically significant for low selenium, the selenium theory of schizophrenia is evaluated by the principles of environmental epidemiology. Although this examination finds the theory deficient, research questions are generated to test the theory further and to investigate the causes of schizophrenia.