Pharmacy researchers find mom’s marijuana use may impair baby’s memory

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With more and more states legalizing marijuana, use of the illicit drug for any purpose—medicinal or otherwise—is increasing, even in pregnant women.

A 2018 study out of Colorado—where recreational marijuana has been legal since 2014—showed infants exposed to the drug in the womb were 50 percent more likely to have a low birth weight. Another study found the majority of Colorado dispensaries—69 percent—recommended pot as treatment for morning sickness.

When Priyanka Pinky, a doctoral student in Auburn’s Harrison School of Pharmacy under the direction of Drs. Vishnu Suppiramaniam and Miranda Reed, heard about a recent report claiming the number of women using marijuana during pregnancy had doubled in the past 15 years, she wondered what other effects it would have on the developing baby.

A medical doctor from Bangladesh, Pinky studied tetrahydrocannabinol, or THC—the active ingredient in marijuana—on rodent models to see what effect there was on the offspring’s memory. Pinky is the lead graduate student on the project, and is assisted by Jenna Bloemer, Yifeng Du, Sharay Setti, Ryan Heslin and Warren Smith.

The research team administered THC to pregnant rodent mothers and found that THC could cross the blood placental barrier—meaning it could transfer from the mother’s blood to        the baby—and subsequently impact the growing fetus.

The team conducted several behavioral experiments and observed the young offspring to be forgetful.

“They could not perform the given task as efficiently as normal offspring of the same age,” Pinky explained. “This made us to think ‘what is the reason behind this?’ We investigated further in the molecular level and we identified the culprit.”

The Neural Cell Adhesion Molecule—a protein in the brain—works like an adhesive, maintaining the connection between neurons in the brain’s hippocampus, where memories are formed. The adhesive connection facilitates the formation of memory and keeps memory intact.

“We found that this protein is significantly reduced in the brain of the THC-exposed animals,” said Pinky. “Since there is reduced adhesion between neurons, memory is impaired.”

Why pregnant women?

Suppiramaniam and Reed have extensive experience in prenatal research and expected THC to have deleterious effects on the brains of the offspring.

“This study is timely because marijuana use among pregnant women is increasing,” Suppiramaniam said.

Reed said the popularity among pregnant women could be because “everybody’s talking about legalizing.” To date, 33 states and the District of Columbia have legalized the drug in some form, making it more accessible to the masses.

Whether it’s to cope with morning sickness or not, “a lot of people assume it’s okay to smoke during pregnancy,” she said, especially if they hear a baby was born with no deficiencies.

Suppiramaniam said it’s difficult to counteract the culture because the mothers “assume it can’t be passed on” to the fetus.

While smoking marijuana is the most prevalent method of consumption, it can also be eaten in edible forms, such as gummy bears and chocolates. Reed said some people—such as pregnant women—likely think an edible form is less harmful than smoking a joint.

It could make sense to these expectant mothers since marijuana reportedly helps cancer patients cope with the side effects of the disease and its treatment.
But medical experts have claimed for decades that smoking cigarettes and drinking alcohol are detrimental to the health and well-being of the baby. How could marijuana be an exception? Experts say it’s not.

The American Medical Association states that taking marijuana during pregnancy is dangerous, and the American College of Obstetricians and Gynecologists discourages pregnant women from using marijuana and other substances.

The Auburn researchers certainly agree that the potential threats to a growing fetus are far too high, yet they have more work to do.

Suppiramaniam said they hope to do more extensive research once a multi-year grant from the National Institutes of Health begins this fall.

National attention

Pinky presented the study findings in November 2018 at the Society for Neuroscience annual meeting—the largest conference for neuroscience in the world—and in April during the 2019 Experimental Biology meeting of the American Society for Pharmacology and Experimental Therapeutics annual meeting.

Additionally, articles about the research findings were published in Newsweek, Scientific American, Health News Digest, Neuroscience News, Science Daily, Daily Mail, Metro and others.