Aug 03 2010

Vegatest – High Tech Pseudoscience

John (a fictitious patient) is suffering from fatigue, poor sleep, difficulty concentrating, and has been noticing little bumps on his skin. His primary care doctor performed a basic workup, which was completely negative, and started asking John about his stress levels and sleep habits. But John was convinced that something was happening to him and so sought additional opinions.

He was referred to Dr. Charles Rank, an allergist, by a work colleague. Dr. Rank took a typical medical history but then also asked John extensively about his environmental exposures and his diet. Dr. Rank believed that John’s history was suggestive of an allergy, and so he brought out his newly acquired Vega II diagnostic testing machine.

The Vega II is a sophisticated-looking piece of electronic equipment, and Dr. Rank seemed confident in working its many knobs and buttons. He attached a few electrodes to John and then pressed a metal probe against his skin while John held in turn a series of glass tubes, each filled with a different substance. Each time the Vega II squealed and beeped, and John could see a gauge registering to varying degrees. It all looked quite complex and impressive.

When the procedure was done Dr. Rank confidently diagnosed John with allergies to dairy and gluten, and recommended specific changes to his diet. The diet would not be easy, but John was relieved to have found a specific diagnosis for his symptoms. He left Dr. Rank’s office feeling a little better already.

The story above, while fictional, is all too common. It is also nothing new – dubious practitioners have been dazzling their patients with fancy bits of equipment for centuries, but especially in the last 100 years or so. The classic example of this is the Abram’s dynomizer and oscilloclast – a literal black box filled with electronic equipment. Slip in a drop of blood on a slide and one machine would spit out a diagnosis (based upon reading the radio frequency vibrations) while the other readjusted the patient’s vibrations into a more healthy harmonic frequency.

The Abrams machine turned out to be nothing but wires connected to lights and buzzers – a scam within a scam – but was marketed as a radio frequency device.

Another class of dubious electronic medical devices essentially measure the galvanic resistance of skin – they are little more than galvanometers with a probe applied to the skin. As usual, Quackwatch has an excellent review article on the topic. Stephen Barrett points out that such devices are known by various names:

The diagnostic procedure is most commonly referred to as Electroacupuncture according to Voll (EAV) or electrodermal screening (EDS), but some practitioners call it bioelectric functions diagnosis (BFD), bio resonance therapy (BRT), bio-energy regulatory technique (BER), biocybernetic medicine (BM), computerized electrodermal screening (CEDS), electrodermal testng (EDT), limbic stress assessment (LSA), meridian energy analysis (MEA), or point testing.

Regardless of the name, they all do the same thing – nothing (from a medical/diagnostic point of view). They simply respond to skin conductance, and the degree of response is overwhelmingly determined by the amount of pressure applied to the skin by the probe (or how tightly they are gripped). This is a nice feature for the dubious practitioner, because they can essentially get the machine to give them any response they want. Or, probably more common, a little ideomotor effect (subconscious muscle movements) is all that is needed to confirm the practitioner’s diagnostic speculations.

Barrett did miss one example – the E-meters used in Scientology auditing to assess for alleged “engrams” are also nothing but skin galvanometers.

This scam goes back to the very roots of our scientific understanding of electricity and magnetism. In essence, as soon as we were able to make galvanometers, someone used them as fake therapeutic devices. In 1795 Elisha Perkins, a fellow Connecticutian, developed his “magnetic attractors” or “tractors” for short. He was riding the coattails of Anton Mesmer and his animal magnetism. The tractors were little more than conducting metal rods that the patient would hold in each hand. According to a review by Roger Macklis:

Despite charges from the Connecticut Medical Society that his device was merely “gleaned up from the miserable remains of animal magnetism,” Elisha Perkins and his son Benjamin (who acquired a British patent for the tractors based on an application entitled “Application of galvanism as a curative agent”) succeeded in giving the metallic tractors the reputation as one of the great therapeutic marvels of turn-of-the-century medicine. Attempts by the medical establishment in America and in Europe to discredit the physiologic basis of the metallic tractor therapies were met with charges of physician greed, professional arrogance, and deliberate restriction of “alternative” health care approaches.

How depressingly familiar that story is – all the elements of its modern counterparts are there: the device was invented by a non-physician (part time mule trader), marketed with scientific jargon and fancy claims, the device itself was able to earn a patent (even though medical claims were not validated) and proper criticisms by the medical establishment were met with charges of elitism and protectionism.

The Vegatest is literally a 200 year old scam, just with updated electronics. As always, I like to see what peer-reviewed publications there are to enlighten our discussion. Searching for “Vegatest” on PubMed yields a grand total of one publication, a 2001 double blind study which concludes:

Electrodermal testing could not distinguish between atopic and non-atopic participants. No operator of the Vegatest device was better than any other, and no single participant’s atopic status was consistently correctly diagnosed. CONCLUSION: Electrodermal testing cannot be used to diagnose environmental allergies.


Using skin galvanometers to pretend to diagnose and/or treat ailments is a class of medical scam with many particular manifestations. Practitioners themselves may be fooled by the device and procedure, and these machines do look impressive and do give feedback. It is a classic pseudoscience – all of the trappings of real science but missing that vital ingredient – actual scientific methodology.

For any such device the skeptic should ask themselves – how has it been validated? Any medical diagnostic device or procedure should be tested in a number of ways. First there is inter-rater reliability – different practitioners should come up with the same diagnosis most of the time. There is also intra-rater reliability – the same practitioner should come up with the same diagnosis when the procedure is repeated.

Tests also need to be compared against a gold standard. In the study cited above, for example, the skin prick test was used as the gold standard – a small amount of substance is placed beneath the skin to see if it provokes a local allergic reaction. When compared to such a gold standard, the specificity and sensitivity of a new test can be determined – how often does it correctly find a present condition, and how often does it falsely register positive?

Of course all of these tests need to be done in a properly blinded fashion.

If there is no gold standard diagnostic test for comparison, then a diagnostic procedure can be validated by demonstrating that it has some predictive utility – it predicts clinical outcome, or response to treatment, for example. We have to show that the results means something.

Without validation from these types of experiments, properly conducted, a diagnostic procedure is not part of legitimate science-based medicine – no matter how many lights and buzzers it has.

5 responses so far