New research led by a team of Australian scientists has found chronic pain is associated with lower levels of key neurotransmitters in the brain. The researchers believe this chemical disruption plays a role in the difficulties people with chronic pain have in regulating negative emotions.
Anxiety and depression are commonly seen in people suffering chronic pain. It is unsurprising those experiencing persistent long-lasting pain can be quick to temper. Pain is exhausting, and chronic pain can wear a person down.
This new research indicates the emotional dysregulation that often goes hand in hand with chronic pain may be rooted in neurochemical changes actually brought on by the pain itself.
“Chronic pain is more than an awful sensation,” explains Sylvia Gustin, senior author on the new study “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.”
The researchers recruited 24 subjects with chronic pain, and 24 matched healthy controls with no history of chronic pain. GABA levels in the medial prefrontal cortex were measured and those subjects with chronic pain were found to have significantly lower levels of the vital neurotransmitter compared to the controls. Interestingly, GABA levels were consistently low across the chronic pain cohort regardless of the type of chronic pain they were suffering from.
“A decrease in GABA means that the brain cells can no longer communicate to each other properly,” says Gustin. “When there’s a decrease in this neurotransmitter, our actions, emotions and thoughts get amplified.”
A prior study from the same research team found low levels of another important neurotransmitter in the medial prefrontal cortex of chronic pain sufferers. That research directly linked low glutamate levels in that brain region with increased feelings of fear and worry.
The researchers are clear to note the findings do not offer evidence of a causal link between chronic pain and these neurotransmitter imbalances. However, Gustin does hypothesize a plausible mechanism by which pain could cause these brain changes.
“Everything starts with stress,” says Gustin. “When someone is in pain, it increases stress hormones like cortisol, which can trigger massive increases in glutamate. This happens during the initial, acute stage of pain.”
It is possible that immune cells in certain parts of the brain then attempt to try and regulate these neurotransmitter abnormalities. But by doing so, in the context of chronic pain, this leads to long-term downregulation of key neurotransmitters needed to manage emotional behaviors.
“As a result of this disruption,” says Gustin, “a person’s ability to feel positive emotions, such as happiness, motivation and confidence may be taken away – and they can’t easily be restored.”
What all this means is that there could potentially be a treatment in the future that can specifically target GABA and glutamate levels in the medial prefrontal cortex to help improve mental health in chronic pain sufferers. While there are already drugs designed to influence GABA and glutamate levels they only work broadly across one’s entire central nervous system.
Gustin says for a drug to be effective in helping chronic pain sufferers and causing little side effects it would have to be very targeted on the medial prefrontal cortex. In the meantime, the researchers suggest therapy programs helping chronic pain sufferers learn ways to better regulate negative emotions can be effective. We may not be able to pharmacologically solve this problem yet, but the brain is plastic enough to learn novel techniques that can help mitigate this chemical imbalance.
“It's important to remember it’s not you – there’s actually something physically happening to your brain,” concludes Gustin. “We don't know why it happens yet, but we are working on finding solutions on how to change it.”
The new study was published in the European Journal of Pain.
Source: UNSW
