Autism is more likely to be present when the child’s father is older, according to a recent study published in the journal Nature. Researchers found an increased risk in autism when a child’s father is 40 years or older. According to the study, an increase of two percent was witnessed by the age of 40.
Researchers believe the increased risk is due to random mutations that occur as males reach advanced age.
According to the group’s researchers, upwards of 20 to 30 percent of autism cases could be attributed to aging fathers over the last several decades. With more people choosing to work longer hours and have children at older ages, the increase in autism has surged forward.
Prior studies have pointed to the age of the mother as a contributing factor in determining the odds of child developmental problems since the risk for chromosomal abnormalities increase as mothers age. As the study reports:
“… when it comes to some complex developmental and psychiatric problems, the lion’s share of the genetic risk originates in the sperm, not the egg.”
A study published in the New York Times in April found the same type of correlation in men aged 35 compared to men aged 25. This new study is the first time an actual calculation based on percentage increases has been revealed as men age.
In the study, it was discovered that children born to a 20-year-old man have 25 random mutations while that number increases by two mutations per year through the age of 65.
Mutations on the mothers side remain at 15 regardless of age.
The study was completed by the Icelandic firm Decode Genetics and involved 78 parent-child trios in which both parents showed no signs and had no history of mental disorders yet produced children with autism or schizophrenia.
While most mutations are harmless to children, there are several mutations which have been shown to produce negative results. The more mutations a child undergoes, the higher the risk of mental disorders.
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