According to Cate Varney, a physician who treats patients with obesity at UVA Health, "we're leveling the playing field with these medications."

Although respondents were mostly supportive of adults using GLP-1 drugs for weight-loss, their answers were more mixed when it came to children. Only 35% of respondents said it was a good idea for children ages 12-17 with obesity or a weight-related health condition to use GLP-1 drugs, and only 8% said the same for children who were not obese or did not have a weight-related health condition.

"We think the liver and kidney are just doing their jobs," Garcia said. "On the other hand, the brain has limited clearance systems."

It's also possible that plastics stick to the brain better, since it's around 60% fat, according to Matthew Campen, a toxicologist, professor of pharmaceutical sciences at the University of New Mexico, and lead author of the study.

"If you've ever cleaned a Tupperware bowl that had bacon grease or butter in it, you know it's hard to get fat off plastic," Campen said. "It's possible the nanoparticles are hijacking their way in through lipids."

Discussion

This study isn't the first time researchers have found microplastics in the brain. Last year, researchers also found significantly higher levels of microplastics in more recent brain samples than older ones — however, this study found that pieces of plastic are reaching deeper into the frontal cortex.

Phoebe Stapleton, a professor of pharmacology and toxicology at Rutgers University, said that scientists have long wondered whether microplastics have the ability to pass through the blood-brain barrier.

"This paper provides clear evidence that micro- and nanoplastics are indeed in the human brain," she said.

Researchers have previously used mice to study how microplastics in the brain could affect health. In one study, researchers gave mice water laced with tiny polystyrene particles — the same type of plastic used in plastic foam and yogurt containers. After three weeks of exposure, the mice demonstrated cognitive changes, including changes consistent with early markers of Alzheimer's disease.

However, researchers caution it's too early to connect microplastics to cognitive problems given how dementia alters the body. Patients with dementia have a weaker blood-brain barrier and have more difficulty clearing toxins in the brain, meaning that the high number of microplastics in the brain could be an effect of dementia or Alzheimer's rather than a cause.

Richard Thompson, a professor of marine biology at the University of Plymouth and the first scientist to coin the term "microplastics," said that linking the particles to various health effects is "far more challenging" than simply identifying them.

Campen similarly advised caution when interpreting the results of his study, though he added that the number of plastics produced globally doubles every 10 to 15 years, which suggests that humans' level of exposure has increased significantly. "To see it go up 50% in eight years in human organs … I think that's perfectly in line with what we're seeing in the environment," he said.

However, Campen noted that it's not definitively known whether microplastics in the brain are dangerous, and added that it would be extremely difficult, if not impossible, to avoid them.

"They really are everywhere," he said, adding that he doesn't think people should make dramatic changes in their diet or lifestyle "to avoid something that may not be avoidable."