Delaying Fatherhood Might Affect the Kids
Study finds that children of older dads have lower IQ scores
(HealthDay News) -- Women, it seems, don't own the biological clock.
Researchers have found that children born to older fathers may be slightly less intelligent than children born to younger dads.
Compared with kids of 20-year-old men, the offspring of 50-year-olds scored about 6 points lower on the standard IQ test, according to a study in the journal PLoS Medicine.
"We need to worry about age of fatherhood as well as age of motherhood," the study's lead author, Dr. John McGrath, from the Queensland Brain Institute at the University of Queensland in Brisbane, Australia, told HealthDay. "We suspect that more mutations accumulate in sperm as the dads age. These mutations may cause subtle changes in the way the brain develops. But, other social factors are involved also."
Dr. Mary Cannon, an associate professor of psychiatry at the Royal College of Surgeons in Dublin, Ireland, agreed that delaying fatherhood holds risks. "These risks may be subtle, such as a decrement of three to six points on childhood IQ tests, but can also be significant, as the increased risks of serious mental illnesses like schizophrenia and autism," Cannon said. She authored an editorial that accompanied publication of the study.
Her comment was in reference to other studies that have found an increased risk for psychiatric illnesses among children born to older fathers. One such study, published in the Archives of General Psychiatry, found that the risk for bipolar disorder was 37 percent higher in kids born to fathers older than 55 years of age than among the offspring of dads in their 20s. The study also found that the risk for bipolar disorder was increased when dads were younger than 20, as well.
The bottom line is that "the biological clock ticks for men, too," Cannon said.
"There has been a great deal of emphasis for many decades on the risks associated with increasing age at motherhood, but men somehow have the impression that fatherhood can be delayed with no ill effects on offspring," she said. "It may be time to redress this balance in the minds of the public. Increased age at fatherhood has potentially significant effects on both the medical and psychological/intellectual outcomes for children."
McGrath's study included information on more than 33,000 Americans who were born between 1959 and 1965, and were participants in the U.S. Collaborative Perinatal Project. Cognitive function was measured at 8 months, 4 years and 7 years of age, and the assessment at age 7 also included tests on reading, spelling and math.
After accounting for possible confounding factors, such as family income or education, the researchers found that kids born to fathers who were older than 50 scored an average of 100.7 on the standard IQ test, compared with a score of 106.8 for children born to 20-year-old men.
"We need to work out what underlies this association," McGrath said.
The researchers also analyzed the data to see what effect a mother's age might have on her children's intelligence, and they found the opposite effect. Children born to older mothers scored higher on the intelligence tests.
On the Web
To learn more about male and female infertility, visit the U.S. National Institute of Child Health and Human Development.
SOURCES: HealthDay News; John McGrath, M.D., Ph.D., professor and director, epidemiology and developmental neurobiology, Queensland Brain Institute, University of Queensland, Brisbane, Australia; Mary Cannon, M.D., Ph.D., associate professor, psychiatry, Royal College of Surgeons in Ireland, Dublin; March 2009, PLoS Medicine; September 2008, Archives of General Psychiatry
Author: Serena Gordon
Publication Date: March 31, 2010
Copyright © 2010 ScoutNews, LLC. All rights reserved.