What chronic pain does to your brain – ABC News Australia – March 2016 – by Lynne Malcolm and Olivia Willis
At least one in five Australians lives with chronic pain, and often the cause is unknown. Scientists are just now discovering the crucial role the brain plays in how pain is experienced, and how it might pave the way for innovative treatment, write Lynne Malcolm and Olivia Willis.
‘At the moment we have focused our work to two areas in the brain,’ says Dr Sylvia Gustin from Neuroscience Research Australia. ‘One is called the thalamus—the other is the prefrontal cortex.’
Described as the ‘border in the brain’, the thalamus acts as the gateway between the spinal cord and higher brain centres.
The below is a new finding:
When you sustain an acute injury
there is an opening in the thalamus
for information to pass through
from the affected body part to the brain.
‘This is very important because then we need to heal, we need to relax, we need to look after ourselves.”
After an acute injury is healed, we know that this border should actually close.
When researching people who experience chronic pain, Gustin identified a key neurological difference:
the opening in the thalamus remains open
long after acute pain is gone.
‘What this means,’ Gustin says, ‘is that in people with ongoing pain, this border is always open. Every signal gets amplified and it results in the experience of pain.’
This rings true to me. Ongoing pain puts me into an altered state that I cannot describe, but that feels “broken” and “vulnerable”, and makes my emotional reactions quicker and stronger.
The thalamus has a much more complicated function than originally believed. (See addendum at end of this post)
Researchers also found people with chronic pain experienced a reduction in the volume of their prefrontal cortex—the region of the brain that is understood to regulate emotions, personality expression and social behaviour.
This is an excellent explanation for the emotional disturbances caused by chronic pain.
Instead of claiming that depression and anxiety cause chronic pain, scientists should look at how this continued signal amplification by the thalamus and reduction of the ability to regulate emotions causes the mood disorders found in pain patients.
The truth is that chronic pain changes the brain, and these changes cause emotional disturbances (labeled mental disorders). Anyone who has been in pain knows how emotionally charged it becomes, and this article gives concrete biological reasons for this.
Emotional disturbances are initially caused by constant pain, not vice versa. However, once established, the emotional aspects of pain tend to reinforce each other and the pain as well.
‘Every emotion and every cognition is amplified. People with ongoing pain, they anticipate pain with a lot of fear and they worry a lot of the time, and they can’t dampen down these feelings because the prefrontal cortex has lost its ability to dampen down these thoughts.’
The continued insistence that mood disorders, like catastrophizing, are a cause of chronic pain is just that, an insistence, not fact. Studies have only found correlations, not causes, yet the anti-opioid people claim a causal relationship.
‘Twenty per cent try to suicide. A lot of clients who I see, they can’t stop their worrying, they can’t stop their anxiety, and they ask me why.
‘I think showing them that there are subtle changes in the brain—and because of these subtle brain changes, they have these thoughts and they can’t stop it—it helps them to cope with that, because a lot of times they are stigmatised.
‘You can’t see pain, and this is a very big thing for these people,’ says Gustin. ‘With my work, I can educate people that it’s a physical pain that results from subtle changes in the brain.’
According to Gustin, the research demonstrates that interaction between brain cells is damaged in the brains of people with chronic pain.
The importance of perception
there are many surprising factors that influence pain, including the way a person perceives their own body.
‘If we give people [with osteoarthritis] pictures of their hand at different sizes and we say ‘please pick out which one best represents your hand’, they will choose the image that is significantly smaller.
‘But it’s not limited to that—we also see problems with their perception of touch
Stanton says these tests suggest people with chronic pain process location-specific information differently. She hopes to use this new information to develop new treatments.
According to Stanton, the research supports other evidence that suggests that information from one sense—like touch or vision—can modulate information that is coming from another sense.
Below is more information about the thalamus (from Wikipedia):
The thalamus (from Greek θάλαμος, “chamber”) is a midline symmetrical structure of two halves, within the vertebrate brain, situated between the cerebral cortex and the midbrain. Some of its functions are the relaying of sensory and motor signals to the cerebral cortex, and the regulation of consciousness, sleep, and alertness.
The thalamus has multiple functions. It may be thought of as a kind of hub of information. It is generally believed to act as a relay between different subcortical areas and the cerebral cortex. In particular, every sensory system (with the exception of the olfactory system) includes a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.
The thalamus is believed to both process sensory information as well as relay it—each of the primary sensory relay areas receives strong feedback connections from the cerebral cortex.
The thalamus has been thought of as a “relay” that simply forwards signals to the cerebral cortex. Newer research suggests that thalamic function is more selective.