In this study, 50 patients with hypertension were divided into two groups of 25 each. One group of 25 received a specific light force chiropractic adjustment (administered by a chiropractor) to the Atlas vertebrae (uppermost bone in the neck). The other group of 25 received a similar procedure but with no adjustment being given. Researchers called this procedure the "sham adjustment". Since the type of adjustment given was very light force, the patients involved in this study did not know if they were receiving the real or sham adjustments.
The results were surprising to even the medical researchers conducting the study. After 8 weeks of care the 25 people in the group receiving the real chiropractic adjustments all showed a significant reduction in blood pressure compared to the group that received the sham adjustment. Those patients who got the real adjustment showed an average of 14 mm Hg greater drop in systolic blood pressure (the top number in a blood pressure count), and an average of 8 mm Hg greater drop in diastolic blood pressure (the bottom blood pressure number) over those who got the fake or sham adjustment.
In his interview with WebMD, study leader George Bakris, MD commented, "This procedure has the effect of not one, but two blood-pressure medications given in combination. And it seems to be adverse-event free. We saw no side effects and no problems."