The way we feel – whether it’s happiness, irritation or any other emotion – has been found to be a balancing act between two chemical messengers in our brains.

But, for the more than 3 million Australians who experience chronic pain, new research has found the likelihood of experiencing negative emotions more often than positive ones is higher.

The new study, which used advanced imaging techniques to scan the brains of volunteers with and without a history of chronic pain, saw that those affected by chronic pain tend to be more anxious and depressed due to disruptions in the communication between cells.

“Chronic pain is more than an awful sensation,” says Associate Professor Sylvia Gustin, the senior author of the new study and a neuroscientist and psychologist at the University of New South Wales and NeuRA.

“It can affect our feelings, beliefs and the way we are.”

What happens in the brain

Emotions are processed by many different areas in the brain, which work together as a network. These regions include the amygdala (responsible for handling positive and negative information), and the prefrontal cortex (which helps us regulate our emotions).

For example, when something frightening is happening, the amygdala sends that information to the prefrontal cortex, which decides whether to communicate with other areas of the brain so you can run away or react in other ways.

This communication requires the help of chemical ‘messengers’ called neurotransmitters, which both help in sending messages between cells and regulating everything from mood to appetite..

One neurotransmitter called gamma-aminobutyric acid (GABA) can stop neurons from becoming over excited to limit communication between the amygdala and the prefrontal cortex.

A second, called glutamate, can excite them.

These neurotransmitters work together to regulate mood, so that our feelings help motivate us to take action when we need to, without feeling overwhelmed or overly anxious.

Amygdala medical labeled vector illustration. Anatomical scheme with visual thalamus, cortex and response to threat. Diagram with cerebrum, thalamus and corpus callosum.

Image: Getty Images

In previous studies on animal models, scientists found that subjects in pain experience varying levels of glutamate. Similarly, a decrease in glutamate has also been seen in humans experiencing chronic pain, matching a decline in their emotional regulation.

However, changes in the amount of GABA in subjects experiencing pain has only been seen in mice, which is where this new study comes in.

The study

By scanning the brains of 48 participants with and without chronic pain, the scientists were able to determine whether the levels of GABA differed when someone was in pain and not in pain.

Though the sample size isn’t large, the study does show enough evidence to support the view that being in pain for a long period of time changes how the brain processes emotions.

“We have discovered, for the first time, that ongoing pain is associated with a decrease in GABA, an inhibitive neurotransmitter in the medial prefrontal cortex. In other words, there’s an actual pathological change going on,” Gustin says.

With lower levels of GABA, it can become harder to dampen the thought processes which deal with our emotional responses and reasoned-out thoughts and actions.

Why it matters

Understanding how pain affects our emotions in the long term can help researchers develop ways to manage its effects, including poorer sleep, additional stress, and feelings of guilt.

“It’s important to remember it’s not you – there’s actually something physically happening to your brain,” says Gustin.

“The brain can’t dampen down these feelings on its own, but it is plastic – and we can learn to change it.”

This research was published in the European Journal of Pain.

This article originally appeared on Over60.