Although being born with attention deficit hyperactivity disorder (ADHD) is common, one study found that people were more likely to have it if their grandmother took a defunct pregnancy drug.

The Defunct DES Drug Has Multigenerational Effects

Medical researchers discovered that grandchildren of women who took a defunct drug called diethylstilbestrol, or DES, were 36 percent more likely to be diagnosed with ADHD. This is likely the first research to show the long-term effects of DES on the brain.

The findings were published on May 21 in JAMA Pediatrics.

From 1938 to 1971, 5 to 10 million women in the United States were prescribed DES as a way to prevent pregnancy complications and miscarriages. Although a 1953 study found no benefit for taking the drug, it was still largely prescribed until a 1971 study linked the drug to rare genital cancers and infertility. The drug then became obsolete.

The study found that DES could directly change DNA sequences or produce epigenetic changes several generations later.

How Did Researchers Link the Defunct Drug To AHDH?

Although researchers previously studied the impact of the drug on mice, there was no evidence that found the connection among multiple generations of humans.

"Our aim was to explore the potential impact of DES use across generations, and specifically on third-generation neurodevelopment," said assistant professor and study coauthor Marianthi-Anna Kioumourtzoglou. "To date, and to our knowledge, no epidemiologic study has assessed multigenerational impacts of DES — or any other endocrine disruptors — on neurodevelopment."

To conduct the study, researchers mailed out questionnaires in 2013 to participants who took the drug in a similar study that began in 1989. From there, they collected data about the women and their offspring. Of the more than 47,000 participants, 861 took the drug while pregnant. Generations later, 5,587 grandchildren were diagnosed with ADHD, and 137 of the grandmothers took the drug while pregnant. The genders of the grandchildren did not have a significant impact on the findings.

There were few potential issues with the study, including participants forgetting details and other reporting errors.

Future Implications From This DES And ADHD Study

One thing researchers did not outline was a potential solution to this problem. They did include a warning to medical professionals.

"Because this was the first ever study to investigate the association between exposure to a potent EDC and third-generation neurodevelopment, our findings should be interpreted with caution. More human studies are warranted to evaluate the same association, as well as the association with environmental EDCs to which humans are daily exposed," said Kioumourtzoglou.