Children born to older fathers may have a higher risk of developing schizophrenia (search) than those with younger dads, according to a new study.

Schizophrenia is a severe, disabling mental illness. Contrary to popular belief, it has nothing to do with multiple or split personalities. Instead, people with schizophrenia hear voices that others don't; they suffer from paranoia and live fearful and withdrawn lives. The first signs of the mental illness emerge around adolescence and early adulthood. The cause of schizophrenia is not known, and there is no cure.

The study is based on more than 750,000 Swedes born between 1973 and 1980, all of whom were still living in Sweden at age 16.

It was conducted by epidemiology professor Finn Rasmussen of Karolinska Institute in Stockholm, Sweden, and colleagues and appears in the Oct. 23 online edition of the journal BMJ Online First.

The researchers examined a variety of records, including Sweden's birth registry and data on Swedish hospital admissions for schizophrenia between 1989 and 2001. The study did not include undiagnosed or non-institutionalized cases.

The study conducted by Rasmussen shows that schizophrenia occurred more frequently among those born to dads older than 30.

The link was stronger in fathers with no family history of schizophrenia, and it remained important even after taking into account other factors that might increase the risk of schizophrenia.

The researchers found that for every 10-year increase in paternal age, there was an almost 50 percent increased risk of schizophrenia in the children.

Children born to older fathers have higher rates of several disorders including certain cancers, write the authors. They say that while several factors are operating to increase the risk of disorders in children born to older fathers, the higher rates of mutations in sperm cells (search) seen in this age group is thought to play a role.

Paternal age wasn't seen as a strong risk factor for other kinds of psychoses.

By  Miranda Hitti, reviewed by  Brunilda Nazario, MD

SOURCES: Sipos, A. BMJ Online First, Oct. 23, 2004, online edition. News release, BMJ Online First. WebMD Medical Reference from Healthwise: "Schizophrenia: Topic Overview." WebMD Medical Reference from Healthwise: "Schizophrenia: Cause."