Paternal age was strongly associated with the diagnosis. The study looked at the occurrence of schizophrenia in families. It is published in the Archives of General Psychiatry, April 2001 edition. This marks the first time paternal aging has been associated with a psychiatric illness. Results may surprise the public but not scientists.
New mutations are key.
That is because, Crow said, mutations occur during divisions of the cells that eventually become sperm and older fathers have much more time for cell divisions and mutations to accumulate. By age 40, a man's cells have undergone about 660 divisions. By contrast, a woman's egg cells divide just 24 times, almost all during fetal life. With each cell division in an aging man, the odds go up for a mutation occurring in the genes that cause schizophrenia, Crow said. The incidence of schizophrenia remains fairly constant around the world and across cultures.