Are there risks to being an older dad?

RESEARCH after research has pointed to links between older dads and problems with their children, but at least one local doctor is reassuring men otherwise.

Most recently, a French study showed that older men produce more gene mutations in the children they sire, boosting their risk of schizophrenia and autism and possibly other diseases.

A father’s age is by far the biggest factor determining the rate of new, uninherited genetic mutations in his offspring, the paper published last year in the journal Nature said.

From a man’s peak reproductive years in adolescence, the rate of new or “de novo” gene mutations triggered at conception in his children rises by about two per year, the study found.

The rate doubles every 16 years, meaning that the baby of a 36-year-old father would have twice as many new mutations than that of a 20-year-old.

But Dr Orlando Thomas, general practitioner, said while a man’s fertility naturally declines with age making him less likely to get a woman pregnant, children born to older dads are no more at risk than those born to men 35 and under. Neither are the fathers themselves at risk.

“There is no risk to an older man fathering a child, as opposed to a woman,” he said. “The eggs that a woman has, she is born with them, so if she is 40 the eggs are 40 years old. So those eggs are old. But with men, the sperm are made every day so there is no increased risk of abnormalities and any kind of deformities with children of older men. The babies will come out just as good as with men who are young,” he declared.

“An older man’s sperm is just as fresh as the younger man’s sperm, it’s just that the sperm count and the strength of the sperm will get less. So they are less likely to get a woman pregnant but there is no risk involved.”

But the research says:

Older fathers’ children are less intelligent — March 2009

Children fathered by older men are likely to be less intelligent than the offspring of younger dads, Australian and US scientists have found.

The surprise result contrasted sharply with earlier studies showing that older mothers produced children more likely to record above average intelligence scores, the researchers concluded.

Lead scientist John McGrath, from the Brisbane-based Queensland Brain Institute, said the result was a world first and had implications for men in Western societies who have delayed fatherhood until their 40s or older.

“The results were quite startling as it was thought that the age of the father was less of a concern compared to the age of the mother,” McGrath said.

“Now we are getting more evidence of the age of the father being just as important — the older a dad is, the worse his children tend to do in intelligence tests.”

Researchers examined data collected on 33,000 children in the United States between 1959 and 1965 fathered by men aged from 15 to 65.

They found that the children of older dads performed less well in intelligence tests conducted at age eight months, four years and seven years.

The researchers said previous studies had linked older fathers to an increased risk of health problems in their children, including schizophrenia, autism, dyslexia, epilepsy and dwarfism.

However, the study published in the US journal Public Library of Science Medicine is the first to suggest there is also a link with general intelligence.

One theory about the difference in results for older fathers and mothers lies in differences between the male and female reproductive systems.

“We are concerned that older men accumulate more mutations in the developing sperm cells,” McGrath said.

“These mistakes then pile up and increase the risks of problems in the children, and it is possible that these mistakes will carry on into the next generation.”

Older fathers more likely to have autistic children — September 2006

Children of men aged 40 and older have a significantly increased risk of having autism spectrum disorders compared with those whose fathers are younger than 30 years, according to an article in Archives of General Psychiatry, one of the Journal of the American Medical Association (JAMA)/Archives publications. Autism is characterised by social and language abnormalities and repetitive patterns of behaviour, according to background information in the article.

Autism and related conditions, known collectively as autism spectrum disorders, have become increasingly common, affecting 50 in every 10,000 children as compared with five in 10,000 two decades ago. This increase is partially due to higher levels of awareness and changes in diagnosis processes, but could also reflect an increase in incidence of autism, according to the authors. Older parental age has previously been linked to abnormalities in the brain development of children; however, few studies have effectively examined the effect of mothers’ and especially fathers’ ages on autism.

Dr Abraham Reichenberg of the Mount Sinai School of Medicine, New York, and Institute of Psychiatry, King’s College London, and colleagues evaluated this association in children born during the 1980s in Israel. All men and three-fourths of the women born in these years were assessed by the draft board at age 17, during which time any psychiatric disorders were recorded. Among the paternal age groups of 15 to 29 years, 30 to 39 years, 40 to 49 years and older than 50 years, there were one case, 13 cases, 62 cases and 34 cases, respectively, of autism spectrum disorders. Advancing age among fathers was associated with increased risk of autism. This association persisted after the researchers controlled for year of birth, socio-economic status and the age of the mother, such that the odds of autism spectrum disorder were nearly six times greater among children of men aged 40 and older than those of men 29 years and younger.

Kids of older dads run greater risk of bipolar disorder — September 2008

Children born to an older father run a greater risk of developing a bipolar disorder than other kids, a Swedish study showed.

“Children whose father was 55 years old or more (at the time of conception) run about a 37-per cent greater risk of suffering from (bipolar disorder) than children whose fathers were in their 20s,” Emma Frans, a researcher at Karolinska Institute in Stockholm said.

Bipolar disorder, also known as manic depression, is a severe mood disorder involving alternating episodes of mania and depression.

The study surveyed more than 13,000 patients in Sweden diagnosed with bipolar disorder, and found that the older their fathers were the more likely they were to have the condition.

Frans said the explanation was genetic.

“Unlike women, men’s reproductive cells continue to divide throughout their lifetime, which increases the risk of DNA copy errors over the years,” she said.

The offspring of older mothers also had an increased risk, but it was less pronounced than the paternal effect, the study said.

Older fathers have previously been identified as one of the factors behind other disorders such as schizophrenia and autism.

About one per cent of the Swedish population suffers from bipolar disorder, the study said.