Autism Linked To Maternal Grandmother's Smoking During Pregnancy, New Study Says

A new study has found a link between autism and the smoking habits of the child's maternal grandmother.

In a study published April 27 in Scientific Reports, scientists at the University of Bristol studied 14,500 participants in its Children of the 90s, which studied kids in the Avon, UK, area born in 1991 to 1992. They found a link between children diagnosed with autism spectrum disorder and their maternal grandmother's smoking.

"If a girl's maternal grandmother smoked during pregnancy, the girl is 67 percent more likely to display certain traits linked to autism, such as poor social communication skills and repetitive behaviors"
In addition, the researchers found that the grandmother had a 53 percent chance of having a grandchild afflicted with autism spectrum disorder.The scientists theorize that the eggs of the mother were damaged after being exposed to her mother's cigarette smoke, affecting the development of her child, notes one of the study authors, Professor Marcus Pembry of the University of Bristol.
"In terms of mechanisms, there are two broad possibilities. There is DNA damage that is transmitted to the grandchildren or there is some adaptive response to the smoking that leaves the grandchild more vulnerable to ASD. We have no explanation for the sex difference, although we have previously found that grandmaternal smoking is associated with different growth patterns in grandsons and granddaughters."
Professor Jean Golding, another coauthor of the study from the University of Briston, said the findings offer one more reason for people to stop smoking.
"We already know that protecting a baby from tobacco smoke is one of the best things a woman can do to give her child a healthy start in life. Now we've found that not smoking during pregnancy could also give their future grandchildren a better start too. We have started studying the next generation of participants, so eventually, we will be able to see if the effect carries down from the great-grandparents to their great-grandchildren too."
The cause of autism remains somewhat of a mystery. According to the Autism Society, it is generally accepted that autism spectrum disorder is caused by abnormalities in brain structure or function, but how that occurs is not entirely known.
"Brain scans show differences in the shape and structure of the brain in children with autism compared to in neurotypical children. Researchers do not know the exact cause of autism but are investigating a number of theories, including the links among heredity, genetics and medical problems."
There can be a genetic link, AS notes. Researchers are investigating the theory that under certain conditions, a "cluster of unstable genes may interfere with brain development, resulting in autism."

Other researchers believe autism occurs during pregnancy or delivery as a result of environmental factors that may include viral infections, metabolic imbalances or exposure to chemicals. The latter of which would certainly fall under the purvue of the Bristol findings.

In the U.S., one in 68 children has autism spectrum disorder, according to the Centers for Disease Control and Prevention.

The cessation of smoking is ever more important as new evidence of the harmful and dangerous effects of smoking are revealed, lead researcher Sarah Nash told The Chicago Tribune.

"Regardless of their age, all smokers benefit from quitting. Also, smoking patterns early in life may still affect mortality even 50 to 60 years later. So, it is important to support efforts to prevent adolescent smoking initiation."
The team says further research is needed to determine what the molecular changes might be in the egg that leads to autism in children whose maternal grandmother smoked and to see whether the same associations are present in other groups of people besides those in the UK study.

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