Plastic is in our clothes, cars, mobile phones, water bottles and food containers. But recent research adds to growing concerns about the impact of tiny plastic fragments on our health.

A study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as scary, shocking and alarming.

But what exactly are microplastics? What do they mean for our health? Should we be concerned?

What are microplastics? Can you see them?

We often consider plastic items to be indestructible. But plastic breaks down into smaller particles. Definitions vary but generally microplastics are smaller than five millimetres.

This makes some too small to be seen with the naked eye. So, many of the images the media uses to illustrate articles about microplastics are misleading, as some show much larger, clearly visible pieces.

Microplastics have been reported in many sources of drinking water and everyday food items. This means we are constantly exposed to them in our diet.

Such widespread, chronic (long-term) exposure makes this a serious concern for human health. While research investigating the potential risk microplastics pose to our health is limited, it is growing.

How about this latest study?

The study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.

These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.

The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.

They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.

The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased human exposure.

The microplastics found in this study were mostly composed of polyethylene. This is the most commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.

This is the first time microplastics have been found in human brains, which is important. However, this study is a “pre-print”, so other independent microplastics researchers haven’t yet reviewed or validated the study.

How do microplastics end up in the brain?

Microplastics typically enter the body through contaminated food and water. This can disrupt the gut microbiome (the community of microbes in your gut) and cause inflammation. This leads to effects in the whole body via the immune system and the complex, two-way communication system between the gut and the brain. This so-called gut-brain axis is implicated in many aspects of health and disease.

We can also breathe in airborne microplastics. Once these particles are in the gut or lungs, they can move into the bloodstream and then travel around the body into various organs.

Studies have found microplastics in human faeces, joints, livers, reproductive organs, blood, vessels and hearts.

Microplastics also migrate to the brains of wild fish. In mouse studies, ingested microplastics are absorbed from the gut into the blood and can enter the brain, becoming lodged in other organs along the way.

To get into brain tissue, microplastics must cross the blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.

Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the urine, testes and placenta, where they have already been found in humans.

Is this a health concern?

We don’t yet know the effects of microplastics in the human brain. Some laboratory experiments suggest microplastics increase brain inflammation and cell damage, alter gene expression and change brain structure.

Aside from the effects of the microplastic particles themselves, microplastics might also pose risks if they carry environmental toxins or bacteria into and around the body.

Various plastic chemicals could also leach out of the microplastics into the body. These include the famous hormone-disrupting chemicals known as BPAs.

But microplastics and their effects are difficult to study. In addition to their small size, there are so many different types of plastics in the environment. More than 13,000 different chemicals have been identified in plastic products, with more being developed every year.

Microplastics are also weathered by the environment and digestive processes, and this is hard to reproduce in the lab.

A goal of our research is to understand how these factors change the way microplastics behave in the body. We plan to investigate if improving the integrity of the gut barrier through diet or probiotics can prevent the uptake of microplastics from the gut into the bloodstream. This may effectively stop the particles from circulating around the body and lodging into organs.

How do I minimise my exposure?

Microplastics are widespread in the environment, and it’s difficult to avoid exposure. We are just beginning to understand how microplastics can affect our health.

Until we have more scientific evidence, the best thing we can do is reduce our exposure to plastics where we can and produce less plastic waste, so less ends up in the environment.

An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.

Sarah Hellewell, Senior Research Fellow, The Perron Institute for Neurological and Translational Science, and Research Fellow, Faculty of Health Sciences, Curtin University; Anastazja Gorecki, Teaching & Research Scholar, School of Health Sciences, University of Notre Dame Australia, and Charlotte Sofield, PhD Candidate, studying microplastics and gut/brain health, University of Notre Dame Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Can you remember a time when you felt stressed leading up to a big life event and then afterwards felt like a weight had been lifted? This process – the ramping up of the stress response and then feeling this settle back down – shows completion of the “stress cycle”.

Some stress in daily life is unavoidable. But remaining stressed is unhealthy. Chronic stress increases chronic health conditions, including heart disease and stroke and diabetes. It can also lead to burnout or depression.

Exercise, cognitive, creative, social and self-soothing activities help us process stress in healthier ways and complete the stress cycle.

What does the stress cycle look like?

Scientists and researchers refer to the “stress response”, often with a focus on the fight-or-flight reactions. The phrase the “stress cycle” has been made popular by self-help experts but it does have a scientific basis.

The stress cycle is our body’s response to a stressful event, whether real or perceived, physical or psychological. It could be being chased by a vicious dog, an upcoming exam or a difficult conversation.

The stress cycle has three stages:

• stage 1 is perceiving the threat
• stage 2 is the fight-or-flight response, driven by our stress hormones: adrenaline and cortisol
• stage 3 is relief, including physiological and psychological relief. This completes the stress cycle.

Different people will respond to stress differently based on their life experiences and genetics.

Unfortunately, many people experience multiple and ongoing stressors out of their control, including the cost-of-living crisis, extreme weather events and domestic violence.

Remaining in stage 2 (the flight-or-flight response), can lead to chronic stress. Chronic stress and high cortisol can increase inflammation, which damages our brain and other organs.

When you are stuck in chronic fight-or-flight mode, you don’t think clearly and are more easily distracted. Activities that provide temporary pleasure, such as eating junk food or drinking alcohol are unhelpful strategies that do not reduce the stress effects on our brain and body. Scrolling through social media is also not an effective way to complete the stress cycle. In fact, this is associated with an increased stress response.

Stress and the brain

In the brain, chronic high cortisol can shrink the hippocampus. This can impair a person’s memory and their capacity to think and concentrate.

Chronic high cortisol also reduces activity in the prefrontal cortex but increases activity in the amygdala.

The prefrontal cortex is responsible for higher-order control of our thoughts, behaviours and emotions, and is goal-directed and rational. The amygdala is involved in reflexive and emotional responses. Higher amygdala activity and lower prefrontal cortex activity explains why we are less rational and more emotional and reactive when we are stressed.

There are five types of activities that can help our brains complete the stress cycle. https://www.youtube.com/embed/eD1wliuHxHI?wmode=transparent&start=0 It can help to understand how the brain encounters stress.

1. Exercise – its own complete stress cycle

When we exercise we get a short-term spike in cortisol, followed by a healthy reduction in cortisol and adrenaline.

Exercise also increases endorphins and serotonin, which improve mood. Endorphins cause an elated feeling often called “runner’s high” and have anti-inflammatory effects.

When you exercise, there is more blood flow to the brain and higher activity in the prefrontal cortex. This is why you can often think more clearly after a walk or run. Exercise can be a helpful way to relieve feelings of stress.

Exercise can also increase the volume of the hippocampus. This is linked to better short-term and long-term memory processing, as well as reduced stress, depression and anxiety.

2. Cognitive activities – reduce negative thinking

Overly negative thinking can trigger or extend the stress response. In our 2019 research, we found the relationship between stress and cortisol was stronger in people with more negative thinking.

Higher amygdala activity and less rational thinking when you are stressed can lead to distorted thinking such as focusing on negatives and rigid “black-and-white” thinking.

Activities to reduce negative thinking and promote a more realistic view can reduce the stress response. In clinical settings this is usually called cognitive behaviour therapy.

At home, this could be journalling or writing down worries. This engages the logical and rational parts of our brain and helps us think more realistically. Finding evidence to challenge negative thoughts (“I’ve prepared well for the exam, so I can do my best”) can help to complete the stress cycle.

3. Getting creative – a pathway out of ‘flight or fight’

Creative activities can be art, craft, gardening, cooking or other activities such as doing a puzzle, juggling, music, theatre, dancing or simply being absorbed in enjoyable work.

Such pursuits increase prefrontal cortex activity and promote flow and focus.

Flow is a state of full engagement in an activity you enjoy. It lowers high-stress levels of noradrenaline, the brain’s adrenaline. When you are focussed like this, the brain only processes information relevant to the task and ignores non-relevant information, including stresses.

4. Getting social and releasing feel-good hormones

Talking with someone else, physical affection with a person or pet and laughing can all increase oxytocin. This is a chemical messenger in the brain that increases social bonding and makes us feel connected and safe.

Laughing is also a social activity that activates parts of the limbic system – the part of the brain involved in emotional and behavioural responses. This increases endorphins and serotonin and improves our mood.

5. Self-soothing

Breathing exercises and meditation stimulate the parasympathetic nervous system (which calms down our stress responses so we can “reset”) via the vagus nerves, and reduce cortisol.

A good cry can help too by releasing stress energy and increasing oxytocin and endorphins.

Emotional tears also remove cortisol and the hormone prolactin from the body. Our prior research showed cortisol and prolactin were associated with depression, anxiety and hostility.

Action beats distraction

Whether it’s watching a funny or sad movie, exercising, journalling, gardening or doing a puzzle, there is science behind why you should complete the stress cycle.

Doing at least one positive activity every day can also reduce our baseline stress level and is beneficial for good mental health and wellbeing.

Importantly, chronic stress and burnout can also indicate the need for change, such as in our workplaces. However, not all stressful circumstances can be easily changed. Remember help is always available.

If you have concerns about your stress or health, please talk to a doctor.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14 or Kids Helpline on 1800 55 1800.

Theresa Larkin, Associate professor of Medical Sciences, University of Wollongong and Susan J. Thomas, Associate professor in Mental Health and Behavioural Science, University of Wollongong

This article is republished from The Conversation under a Creative Commons license. Read the original article.