Chiropractic is a diverse collection of beliefs and practices occurring under a broad regulatory label. The differences among various chiropractics are so stark that it is difficult to make general statements about chiropractic practice. At one end of the spectrum, however, are so-called “straight” chiropractors who adhere to the original philosophy of D.D. Palmer – that a vital force they call innate intelligence is response for health, and blockages in the flow of this magical force through the nerves are what cause illness. Such chiropractors believe they can influence non-neuromuscular conditions by restoring the flow of innate blocked by mysterious “subluxations” in the spine.

From we have this definition of “straight” chiropractors:

Because straight chiropractors believe that nearly all diseases are caused by issues with the spine, they don’t believe they need any diagnostic tools. Traditional testing done by medical doctors and hospitals is not even considered by a straight chiropractor as being necessary. Diagnosis is done by finding the subluxations in the spine so that those can be corrected.

This particular version of chiropractic (by some estimates about a third of chiropractors follow this philosophy) is pure pseudoscience. It is, as indicated by the quote above, hostile to science-based medicine.  After a century of such belief there isn’t a bit of evidence to support the notion of innate intelligence, chiropractic subluxations, or health benefits from this approach.

Some straight chiropractors even “specialize” – one specialty, chiropractic neurology, has been getting some press because hockey star Sidney Crosby has been going to a chiropractic neurologist, Ted Carrick, to treat his concussion. The main idea behind chiropractic neurology is the same as for straight chiropractic in general, just applied to neurological disorders.

Carrick claims that he can treat a variety of brain disorders with targeted manipulation and elaborate exercises and routines. In a PBS interview he said:

Well, we’re finding every day that more and more things that we didn’t think were associated with chiropractic treatment can be affected very nicely. There are testimonials from people who have had their eyesight and hearing back, and people waking up from comas.

Waking a patient from a coma is perhaps the ultimate rehabilitative claim in neurology. You will notice, of course, that Carrick refers to only “testimonials”. The reason for that is because there are no published articles establishing such bold claims. Chiropractic neurology does not appear to be based on any body of research, or any accumulated scientific knowledge. I am not aware of any research that establishes their core claims. A search on PubMed for “Carrick T” yielded nothing, and searching on “chiropractic neurology” yielded mostly studies about neurological complications from chiropractic treatment. There was one letter from the President of the International Academy of Chiropractic Neurology.

I followed that link to the IACN website, but found no references or links to any published studies establishing the scientific basis of chiropractic neurology. There was no science at all. I also noted that the IACN mission statement does not make any mention of promoting  scientific research or science-based standards. Here it is:

The mission of the IACN is to provide an outlet for expression and communication of professional opinions for the benefit and enhancement of the neurological sciences as they relate to the chiropractic profession for the best service to humankind. Further, the IACN promotes the proper use of principles and techniques in the field of chiropractic neurology and support those principles, policies and practices that seek the attainment of the highest order of excellence in neurologic skills directed at patient care by doctors of chiropractic.

The IACN serves to promote the highest standards of moral and ethical conduct amongst chiropractic neurologists.

The wording is interesting – they talk about opinions, principles, and practices. They refer to the “enhancement of the neurological sciences” but it is not clear what that means.

Chiropractic neurology appears to me to be the very definition of pseudoscience – it has all the trappings of a legitimate profession, with a complex set of beliefs and practices, but there is no underlying scientific basis for any of it.

It should be noted that neurological symptoms are often especially vulnerable to placebo effects.  Many symptoms, like vertigo, or “fogginess” are highly subjective. There is also a well-established “cheerleader” effect – if you take anyone with chronic neurological symptoms (such as chronic deficits from a stroke) and then give them any intervention, they will perform better. Just getting patients off the couch and moving will have some effect. Careful research is necessary to separate the specific effects of an intervention from the non-specific effects of  motivation, mood, activity, and also just time. The brain can heal itself to some degree, and after an injury there can be an improvement for even years afterward.

Some symptoms are also susceptible to conditioning. Vertigo is perhaps the best example of this. At present the most effective treatment for chronic vertigo (a subjective sense of movement, such as spinning) is vestibular therapy – physical therapy designed to condition the patient to the symptoms, to diminish them over time. It is therefore possible that some chiropractic neurology interventions are simply providing this known mechanism. For example, here is a description of Carrick’s treatment of Hockey player, Crosby:

Carrick then signals to restart the gyroscope—with one difference. This time Crosby will be turned upside-down while he is also spun around. He hasn’t experienced this dual action yet. The door clangs shut. Above it, a stack of red, yellow and green lights shines while 10 high-pitched beeps signal the gyroscope is about to start. Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding!

This is a very dramatic treatment, sure to impress the naive. It follows a common philosophy in dubious neurological treatments – the notion that you can “rebuild the brain” by stimulating it. While it is true that activity and simulation are better than no activity and stimulation, it does not follow that simply increasing stimulation will increase the brain’s plasticity or recovery (a simplistic more-is-better philosophy). That basic notion was researched and discarded decades ago, for example with specific reference to psychomotor patterning treatments.

Chiropractic neurology is an excellent example of exactly why we need science-based practices. Without a grounding in objective evidence there does not appear to be any limit to the degree that beliefs systems can be led astray. Any treatment can deceptively seem to work, and humans are very good at backfilling in justifications and explanations for phenomena that do not even exist. Left to our own devices we will tend to develop elaborate, but entirely fictitious, belief systems.

We figured our centuries ago, however, that systematic methods of controlling variables, controlling for bias, and rigorous statistical analysis can compensate for such human foibles. Until chiropractic neurology (and similar practices) avail themselves of such methods there is no reason to take their claims seriously.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the president and co-founder of the New England Skeptical Society, the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also contributes every Sunday to The Rogues Gallery, the official blog of the SGU.