"The groundwork of all happiness is health." - Leigh Hunt

New study links maternal THC use to autism and ADHD

July 7, 2023 – Researchers have found that consuming delta-9-tetrahydrocannabinol, or THC, while pregnant may cause genetic changes as the child grows within the womb which can be consistent with those seen in individuals with autism spectrum disorders and a focus deficit hyperactivity disorder.

The recent findings, which were presented on Thursday in Clinical Epigeneticscome from experiments conducted on nonhuman primates by researchers at Oregon Health & Science University. The researchers gave pregnant primates edibles containing THC, the psychoactive ingredient in marijuana and cannabis products. They found that in places where marijuana and THC products are legal, dispensary staff often recommend the products to pregnant women to alleviate nausea.

“Cannabis is one of the most widely used drugs and is widely available across the country, so there is a general perception that its use is completely safe,” said the study’s lead creator, Dr. Lyndsey Shorey-Kendrick, a computational biologist at OHSU’s Oregon National Primate Research Center, in a opinion“The reality is that cannabis still poses many health risks for certain populations, including pregnant women. By better understanding the effects, we can better communicate the risks to patients and promote safer habits during the vulnerable prenatal period.”

In their article, the researchers noted that previous studies have linked maternal cannabis use to an increased risk of preterm birth, stillbirth and low birth weight. Studies in mice have shown that use increases anxiety and alters the DNA of the brains of baby mice. Previous research has also shown links between maternal cannabis use and autism spectrum disorders, ADHD, mental disability and learning disabilities, and other neuropsychiatric disorders, they wrote.

The goal of this latest study was to know how THC alters genes during fetal development. Researchers gave a bunch of 5 pregnant research monkeys edible THC each day throughout their pregnancy, and one other group of 5 pregnant monkeys received a placebo. The monkeys delivered their infant via cesarean section, and tissue samples were taken from five sites during birth: the placenta, a lung, two parts of the brain, and the guts. They found that THC exposure affected gene expression in all five tissue types, particularly the placenta. The placental tissue from the THC group also bore similarities to previously studied human placental samples obtained from moms whose babies were later diagnosed with autism.

The primates utilized in the research, called rhesus monkeys, have DNA that's 93% much like that of humans and have been used to develop a number of the world's biggest human medical advances, including vaccines and reproductive treatments, in line with summaries from Washington University in St. Louis, MO, and the University of Wisconsin.

“It's not common for doctors to discuss cannabis use with patients who are pregnant or trying to become pregnant,” Jamie Lo, MD, researcher and associate professor of obstetrics and gynecology on the OHSU School of Medicine, said in a press release. “I hope our work can help open a broader dialogue about the risks of cannabis use during the preconception and pregnancy periods so we can improve children's health in the long term.”