Schizophrenia as a recent disease.

The hypothesis that schizophrenia is a recent disease can explain why descriptions of schizophrenia-like disorders were rare before 1800, why the prevalence of insanity in the Western world increased during the 19th but remained low in the non-Western world until the 20th century, and why schizophrenia has become milder in the West during recent decades. It also explains why schizophrenia has 'persisted' in spite of its associated low fertility. The evidence for the hypothesis is somewhat frail, but perhaps not more so than that for alternative hypotheses.