Like 35 and Down Syndrome for Women

Old fathers raise risk of brain disorder
By Jacqueline Maley
October 23, 2004
There is a "strong association" between men who become fathers after the age of 50 and of schizophrenia in their children, a study has found.

Swedish research that tracked over 700,000 young people found 15 per cent of schizophrenia cases could be attributed to older fathers. Researchers believe the link may be due to sperm mutations, which accumulate as men get older.

Compared with men who become fathers between 21 and 24, those who father children at the age of 50 or older have four to five times the chance of their offspring developing schizophrenia. The link was stronger if there was no family history of the disorder.

The link between schizophrenia and older paternity had been made before, but this was the first large study to look at a range of factors that could confound the results, said Professor John McGrath, a psychiatric epidemiologist at the Queensland Centre for Mental Health Research.

"If all babies had fathers less than 30, the paper suggests, the incidence of schizophrenia would reduce by 15 per cent," he said.

In the 1970s it was commonly believed that mothers caused their children's schizophrenia, Professor McGrath said. "There is now an interesting new lead looking at father's age, and this study adds weight to that.

"Schizophrenia is a group of brain disorders, and we're struggling to find out what causes them. This study ... will help to tease apart the causal pathway."

In Australia about 1 per cent of people develop schizophrenia. A study published in 2002 in People and Place, a Monash University journal, found consecutive generations of Australian men were becoming parents later.

In 2002 the average age of fathers was 32, compared with an average age of 29 in 1982, according to data from the Australian Bureau of Statistics.

The executive director of the mental health lobby group SANE Australia, Barbara Hocking, said the Swedish research, published in the British medical journal BMJ, was "major, major stuff".

She likened the research to the link between mothers over 35 and an increased risk of Down syndrome in their children. "It helps people understand what risk factors may be, so you can take action to reduce them."