The good news: children of older fathers can be brainier. The bad? They may be more at risk of disease
WaNT to have a brainy child? Then wait until you are over the age of 40 — if you are a man at least.
For according to new U.S. research, the offspring of ‘older’ dads — defined as over the age of 40 — are more likely to be not just intelligent, but more focused on what interests them and less concerned about fitting in. The researchers looked at 15,000 pairs of twins and measured ‘geek-like traits’ when they were 12.
They believe the findings may in part be due to the fact that ‘geekiness’ is an inherited trait, and older fathers are more likely to be the type to be focused on their education and career.
‘There are many benefits to older dads,’ adds Jeremy Davies, a health and social policy expert and spokesman of the Fatherhood Institute, a UK think-tank.
‘They tend to be more financially secure, sure of their decision to have a child and are emotionally settled.’
all good news for the offspring of the likes of George Clooney, who recently became father to twins aged 55, and Mick Jagger, who became a dad for the eighth time at the grand old age of 73.
But it seems they were lucky to have conceived in the first place. For while we all know that a woman’s chance of conceiving drops with age, scientists this week found that the same may be true of men.
The age of first-time fathers is rising — on average, British men first become a father at 33, four years older than 40 years ago. Now a U.S. study has suggested that men in their 40s had a significantly lower birth rate — researchers at the Beth Israel Deaconess Medical Centre in Boston found that those aged 40 to 42 had an average birth rate of 46 per cent, compared with73 per cent for men aged 30 to 35.
here we look at the findings on what this might mean for their offspring . . .
EARLY ARRIVALS
OLDER dads are more likely to have babies born before their due date, and that risk increases with paternal age, according to a study in the March 2005 issue of epidemiology. The researchers thought this might be down to something called ‘paternal placental effect’.
Studies have shown that the father’s genes in the sperm carry the blueprint for the foetus’s side of the placenta. Older sperm may carry a less perfect ‘ blueprint’, so the placenta is less effective.
Being born pre-term has a range of implications for the child’s health. They are more at risk of obesity, which also increases the chance of them developing cardiovascular disease and diabetes.
GENETIC MUTATIONS
The average dad aged 30 passes on 55 mutations — changes in the DNA in a gene — to his offspring, but this doubles by the time a man reaches 47.
These mutations can lead to Down’s syndrome, sickle cell anaemia (a red blood cell disorder) and defects such as heart problems and cleft palate.
‘ Down’s syndrome becomes more likely if a father is older,’ says Christopher Barratt, a professor of reproductive health at the School of Medicine, University of Dundee. ‘There is strong data for this, and the link is well established.’
Research published in November 2005 found men over 50 were more than four times as likely to have a child with Down’s as younger dads. This is one reason UK fertility clinics only normally accept sperm donations from men aged between 18 and 41. ‘you want sperm from young, healthy men that hasn’t had time to build up defects,’ says Dr allan Pacey, professor of andrology at the University of Sheffield.
The risk of having a child with achondroplasia, a type of dwarf- ism, goes up from one in 15,000 to one in 1,923 if the father is 50.
AUTISM FACTOR
The exact cause of autism, which affects how people relate to others, is unknown but there may be a link to paternal age. a study published in 2006 in the archives of General Psychiatry, found that children born to men over 40 had a six times higher risk of having autism compared with those born to men under 30.
Carol Povey, director of the National autistic Society’s Centre for autism, says it is too early to draw conclusions.
‘autism involves many factors, including genetics, the environment and the development of the brain,’ she says.
‘a number of studies suggest a parent’s age could be one of these factors. however, these studies are not definitive.’
attention Deficit hyperactivity Disorder (ADHD), which leads to symptoms such as inattentiveness and hyperactivity, is also more common in the offspring of older fathers. a study published in JAMA in 2013 found that children born to men over 45 were 13 times more likely to be diagnosed with ADHD than children born to men aged between 20 and 24.
Researchers at Columbia University College of Physicians and Surgeons found that men over the age of 50 are around three times more likely to father a child with schizophrenia compared with men aged 25 or under.
CANCER CONCERNS
CHILDREN conceived by men over 40 have a 14 per cent increased risk of childhood leukaemia, and a 70 per cent increased risk of brain tumours, according to studies. If the father is over 45, there is a threefold increase in the risk of a rare eye cancer called retinoblastoma.
‘ This is based on historical epidemiological data which shows there may be a link between poorquality older sperm with DNA damage and the development of these cancers,’ says Professor Barratt. ‘however, the evidence is not easily repeated in a clinical setting, so we don’t yet understand the mechanism for why these cancers would occur.’
Meanwhile, the female children of older dads may be more at risk of developing breast cancer as adults, according to a U.S. study published in 2014.
The daughters of men over the age of 40 have a 60 per cent higher risk of developing breast cancer.
and a team at the City of hope National Medical Center in California, found that women born to a father whose age at her birth was 30 to 34 had a 25 per cent greater risk of developing endometrial (wombe) cancer than those born to a father aged 25 to 29, and were more at risk from breast cancer, too.
Lead researcher Dr yani Lu said there seemed to be a relationship between older fathers and a higher risk of hormone-related cancers.
The reason is unclear, but it may be that decreased circulating hormone levels result in chromosome changes in sperm cells.
AND ON THE UP SIDE...
CHILDREN of older fathers may enjoy greater longevity. That’s because they are born with unusually lengthy telomeres — the protective ends that cap a strand of DNA.
In order to make new cells, DNA makes copies of itself and each time the telomeres are worn down a little. So the longer they are to start with, the more protection they give the DNA. and the longer your telomeres, the longer you tend to live.
The offspring of older fathers have longer telomeres in their sperm and white blood cells, according to a study which was published in 2012 in the Proceedings of the National academy of Sciences USA.
‘It’s interesting, but the length of telomeres does not alone determine when we will die,’ says Professor Barratt.
‘environment and other factors have to be taken into account.’