More than three million Australians experience chronic pain: an ongoing and often debilitating condition that can last from months to years. This persistent pain can impact many parts of a person’s life, with almost half of people with chronic pain also experiencing major anxiety and depression disorders.
Regulating emotions might be harder for people with chronic pain, the study finds. Photo: Shutterstock.
Now, a new study led by UNSW Sydney and NeuRA shows that people with chronic pain have an imbalance of neurotransmitters in the part of the brain responsible for regulating emotions.
This imbalance could be making it harder for them to keep negative emotions in check – and the researchers think persistent pain might be triggering the chemical disruption.
The findings are published today in the European Journal of Pain.
“Chronic pain is more than an awful sensation,” says senior author of the study Associate Professor Sylvia Gustin, a neuroscientist and psychologist at UNSW and NeuRA. “It can affect our feelings, beliefs and the way we are.
“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.”
Neurotransmitters help communicate and balance messages between cells. While some amplify signals (called excitatory neurotransmitters), others weaken them (inhibitive neurotransmitters).
GABA, or γ-aminobutyric acid, is the main inhibitory neurotransmitter in the central nervous system. Its role in the medial prefrontal cortex – the part of the brain where emotional regulation happens – is to help dial down our emotions.
The research team used advanced neurological imaging to scan GABA content in the medial prefrontal cortex of 48 study participants, half of which experienced some form of chronic pain. A/Prof. Gustin says this relatively small sample size is typical for neurological imaging studies, which are costly to run.
The results show that participants with chronic pain had significantly lower levels of GABA than the control group – a pattern that was consistent regardless of their type of chronic pain.
A decrease in GABA means that the brain cells can no longer communicate to each other properly. When there’s a decrease in this neurotransmitter, our actions, emotions and thoughts get amplified.”
Sylvia Gustin, Associate Professor, UNSW
While the link between chronic pain and decreased levels of GABA has previously been found in animal studies, this is the first time it’s been translated to human studies.
A/Prof. Gustin says she hopes the findings are encouraging for people with chronic pain who may be experiencing mental health issues.
“It's important to remember it’s not you – there’s actually something physically happening to your brain,” she says.
“We don't know why it happens yet, but we are working on finding solutions on how to change it.”
Kang, D., et al. (2021) Disruption to normal excitatory and inhibitory function within the medial prefrontal cortex in people with chronic pain. European Journal of Pain. doi.org/10.1002/ejp.1838.