Even short-term exposure to harmful microplastics could lead to signs of dementia, a study suggests.
Researchers at the University of Rhode Island genetically modified mice to have an APOE4 mutation, one of the best-known risk factors for Alzheimer’s disease.
The mice were also exposed for three weeks to polystyrene microplastics, which are used to make Styrofoam and other types of foam and food containers.
Microplastics are tiny particles smaller than a grain of sand that seep from food containers, water and even baby toys into the blood.
From there, they accumulate in the brain, heart and other vital organs and lead to lasting damage.
In the male mice exposed to the toxins, researchers observed the rodents wander around a box they were placed in, rather than cling to the corner of their pen for safety. This lack of regard for safety is often seen in Alzheimer’s.
And female mice showed signs of memory problems when it came to recognizing familiar objects or completing mazes.
The researchers believe these behaviors mimic tell-tale signs of Alzheimer’s disease in humans, as men with the disease are more likely to be indifferent or unmotivated while women have more memory issues.
The study suggests that even being exposed to microplastics for a few weeks could cause lasting damage. And nearly all Americans have detectable levels of the chemicals in their bodies, with exposure starting in the womb.
Researchers at the University of Rhode Island found exposure to microplastics may increase the risk of Alzheimer’s disease in mice (stock image)
Jaime Ross, study author and professor of neuroscience at the University of Rhode Island, told the Washington Post: ‘I’m still really surprised by it. I just can’t believe that you are exposed to these particles and something like this can happen.’
The findings come as nearly seven million Americans are living with Alzheimer’s disease, the most common form of memory-robbing dementia.
About one in 14 people develop the disease by age 65, and one in three are diagnosed by 85.
The study, published last month in the journal Environmental Research Communications, looked at mice who were genetically modified to have the APOE4 mutation, which triples the risk of Alzheimer’s disease.
Around one in four Americans have the mutation.
While the gene on its own significantly increases risk, the researchers caution it does not guarantee developing the condition.
Ross said: ‘If you are carrying APOE4, it doesn’t mean you’re going to develop Alzheimer’s disease.
‘I don’t want to scare anybody. But it is the largest known risk factor.’
Nearly all Americans have been exposed to microplastics, which seep into vital organs and cause untold damage (stock image)
Mice in the study were also exposed to polystyrene microplastics for three weeks in their drinking water. The microplastics were between 0.1 and two micrometers in diameter, which is a fraction of the width of a human hair strand.
After the exposure period, the researchers conducted behavioral testing, such as maze puzzles and object recognition. In one portion, mice were put in a square pen.
The researchers said healthy mice will generally stick to corners and avoid open spaces for safety reasons but male mice with the APOE4 mutation who were exposed to microplastics tended to drift toward the center.
This showed a general lack of motivation or regard for safety, which is common in men with Alzheimer’s.
Female mice did not show the same behavior, but they did have memory issues and trouble remembering familiar objects significantly more than female mice that were not exposed to microplastics.
They also struggled to get through mazes.
‘There were very similar sex differences in mice as what people experience,’ Ross said.
The researchers are unsure exactly why microplastics raise the risk of Alzheimer’s-like behaviors but repeated exposure has been shown to increase oxidative stress, an imbalance of harmful molecules called free radicals.
Oxidative stress induces inflammation and damages cells, including those responsible for memory and executive function, which could increase the risk of Alzheimer’s.
Microplastics can also cross the blood-brain barrier and block blood vessel function, causing brain damage.
The researchers cautioned that it was unclear whether humans would suffer the same effects. They also didn’t take into account aging, which is the main risk factor for dementia.
Ross said her lab is working on further studies to investigate this relationship. ‘The field is so new,’ she said. ‘Any information will help other people design their studies.’
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