science of chiropractic
An emerging body of evidence that spinal manipulation also improves your brain…
The neuroscience studies explore the underlying mechanism of those results—how the spine and central nervous system (CNS) are interconnected and ‘talk’ to each other, and how dysfunction in the spine can affect health and well-being.
A study published this year in the journal Brain Sciences, looked at the effect of chiropractic adjustments in 28 patients with “subclinical” pain—those with a history of intermittent back or neck ache or stiffness for which they were never treated—but who were in pain the day of the experiment. On examination, all had tender spots and restricted joint movement in their spines.
Compared with ‘sham’ adjustments, chiropractic spinal adjustments of these people induced significantly greater brain activity, or ‘cortical excitability’ (which has to do with neuroelectrical signals produced when brain or peripheral muscles are stimulated), as measured by transcranial magnetic stimulation (TMS), which uses magnetic fields to stimulate nerve cells in the brain, as well as arm and leg muscle strength.
Increases in muscle strength have proved to be driven by brain activity resulting from spinal manipulation, and not by any changes made to the spinal cord itself. This offers a host of possibilities for, say, recovering muscle strength after nervous-system injuries. As the study concluded, “spinal manipulation may therefore be indicated” for patients who have lost muscle tone, or are recovering from a stroke or from orthopaedic surgery that affects the muscles. It may even be of interest to athletes who participate in sports.
These findings have confirmed a 2015 study which showed that, following a full-spine chiropractic adjustment session, voluntary leg muscle strength in study participants increased by 16 per cent, while electrical activity readings from the measured muscle increased by nearly 60 per cent. But most spectacularly, the researchers (from the Centre for Chiropractic Research in New Zealand) discovered a 45 per cent increase in the reflex pathway ‘drive’ from the brain to muscle (an indicator of the ability of the brain to activate it). By contrast, the control participants who underwent the sham adjustment actually lost strength and brain drive to the measured muscle.
This same Auckland-based team, led by Haavik and two colleagues is now embarking on some ground breaking research involving brain-body communication in stroke patients.6 A preliminary study had tested the effect of a single chiropractic adjustment on 12 stroke patients, and found that it increased leg muscle strength by an average of 64 per cent and brain drive to the limb by more than 50 per cent. In contrast, both measurements fell after the sham adjustments in the controls.
Ordinarily, you wouldn’t expect to see muscles gain in strength after being asked to repeatedly resist something because muscles become fatigued. Now, that we have the technology to objectively measure an increase in muscle strength after an intervention, Haavik says, these results suggest that” chiropractic care is not only preventing fatigue, but making [muscles] even more efficient at producing force”.
The potential results of the new study could have a significant impact on the role of chiropractic care in people who have reduced muscle function as a result of stroke, she says.
YOUR PLASTIC BRAIN
Haavik is now trying to explain how chiropractic achieves all this, and why restoration of proper movement is able to so profoundly affect the brain and overall health.
The CNS—the brain and spinal cord—and all the nerves beyond the CNS (the peripheral nervous system, or PNS) is a complex network comprising as many as 10 billion nerve cells (also called ‘neurons’) and 60 trillion synapses—tiny little junctions between neurons that mediate the ‘talk’ across highly specialized neural circuits via chemicals called ‘neurotransmitters’. Indeed, nerves feed out of each segment of the spine like strands of spaghetti, and facilitate communication back and forth with various regions of the body.
Everything we do—from our basic motor reflexes to our capacity to experience abstract thoughts and feelings—relies on the precision of the computational processes performed by these CNS and PNS neural circuits. They, in turn, depend on having healthy excitatory and inhibitory systems.
A neuron gets ‘excited’ when it’s ‘talked to’ loudly enough, or stimulated, and this sends an electrical message down one of the neuron’s extensions (called ‘axons’), so allowing it to talk to another nerve cell by releasing more neurotransmitters at the synapses.
Such talk happens all the time as input comes in from our external senses (eyes, ears, mouth, nose and touch), as well as through an inner ‘map’ of the location of our muscles and joints in three-dimensional space relative to each other (proprioception), as the brain carries out its decisions and functions.
Contrary to decades of scientific dogma, a recent wave of research has shown that the brain is actually highly adaptable to its ever-changing environment throughout life. It does this by keeping an up-to-date tab on its sensory inputs and its internal map of the self. This ability to adapt is known as ‘neural plasticity’.
Haavik likens the plasticity of the CNS to the subtle changes in the bed in a flowing stream. “You can never really step into the same river twice; the water, stones and silt of the riverbed are constantly changing,” she says. Likewise, your brain is changing with every thought and every execution, and is in a constant state of flux.
In fact, she believes her research demonstrates that vertebral subluxations) lead to a breakdown in the way the brain perceives and controls the movement of the spine. And this spinal dysfunction doesn’t just affect how the brain then perceives and controls the spine, but also how it perceives and controls other parts of the body as well.
When the brain gets even slightly wrong information, it builds a faulty map that can impede neural signalling as effectively as damped sensory input—like wearing a blindfold or losing the sense of taste. And that translates to faulty functioning.
Chronic pain and neurodegenerative disorders have been linked to these faulty perceptions by the plastic brain. “Pain and conditions with other symptoms don’t necessarily happen all of a sudden for no reason. They can slowly develop without your awareness, a bit like a thousand straws on a camel’s back before it breaks,” says Haavik. “Only when the last straw is added do you feel the effect.”
Haavik’s team hypothesizes that spinal adjustments that restore normal movement also restore more normal data input from the spine to the brain. This, in turn, allows the spinal cord, brain stem and brain to process any incoming information more coherently.
“We believe this to be the mechanisms by which adjustments of vertebral subluxations can improve nervous system function, as observed daily in chiropractic practices all around the world.”
While the New Zealand researchers are reluctant to speculate on immunity, an emerging body of research is demonstrating the interconnectedness of both the nervous and immune systems too. An entirely new lymphatic system in the brain was only discovered in 2015 by a team of researchers at the University of Virginia, which highlights how limited our understanding of the brain, and the effect of the nervous system on global health, still is. It also raises further questions about how improving one system can lead to improvement in the other—and so perhaps why some people experience benefits to their immune-mediated disease with chiropractic manipulations.
“What is becoming clear is that chiropractic care seems to impact our brain’s inner reality by restoring the proper processing and integration of sensory information, which alters the way our brain controls our body,” says Haavik.
“It’s so exciting to see that there are other possible ways now to explain the effects of chiropractic that are actually congruent with current neuroscience,” she adds. “It’s actually more profound and powerful than we could have ever thought.”
Reprint from Circle of Doc’s By: Celeste McGovern
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