New Delhi: Exposure to micro- and nano plastics may be linked to the development of Alzheimer's disease, according to a study in mice. 

Micro- and nano plastics prevalent in the environment routinely enter the human body through the water we drink, foods we eat, and even the air we breathe.

The study, led by researchers from the University of Rhode Island College of Pharmacy, showed that those plastic particles infiltrate all systems of the body, including the brain, where they can accumulate and lead to cognitive decline and even Alzheimer’s disease, especially in those who carry genetic risk factors.

The research follows a previous study that showed how microplastics can infiltrate all systems of the body -- including the blood-brain barrier, which protects the brain from harmful substances as small as viruses and bacteria.

The new study, published in the journal Environmental Research Communications, examined mice that had been genetically modified to include the naturally occurring gene APOE4 -- a strong indicator of Alzheimer’s risk, making people 3.5 times more likely to develop the disease than those who carry the APOE3 variant of the gene that is passed from parents to offspring.

“In these mice, like in people, it’s not a guarantee that you’re going to see any changes in cognition. You could have identical twins, both carrying APOE4, one totally cognitively healthy, and the other could develop Alzheimer’s disease,” said pharmacy assistant professor Jaime Ross from the varsity.

“So that tells us there’s something about lifestyle, something about the environment going on. There are modifiable factors we’re studying related to Alzheimer’s–diet, exercise, vitamins, and especially environmental toxins like microplastics. If you carry the APOE4, and you happen to consume a lot of microplastics, will this contribute to Alzheimer’s disease?” Ross added.

The team then ran the mice through a series of tests to examine their cognitive ability.

“In human Alzheimer’s patients, men tend to experience more changes in apathy; they care less. Women experience more changes in memory. So the memory and the apathy connection are pretty clear: When you expose animals that are carrying the largest known risk factor in humans for developing Alzheimer’s disease to micro- and nanoplastics, lo and behold, their behaviour changes in a sex-dependent manner similar to the sex-dependent differences we see with Alzheimer’s patients,” Ross said.

The results are concerning enough to warrant further study into the cognitive decline caused by exposure to micro- and nanoplastics, which are among the most prominent environmental toxins to which people are routinely exposed, said the team. (IANS)