A study found that acupuncture and a sham version of the same thing both helped reduce the frequency of migraine headaches, for reasons that are not clear, researchers said on Tuesday.

The findings from Technische Universitaet in Munich, Germany, seem to confirm other studies that acupuncture is a beneficial migraine treatment, but do not shed light on exactly why, the authors said.

“Conclusions must be careful, but in the end patients - at least those in the study - seem to benefit in a clinically relevant manner from repetitive needling considered by them as acupuncture,” said Klaus Linde, a physician who was the study’s chief author.

His study, published in this week’s Journal of the American Medical Association, involved 302 migraine patients tested in 2002 and 2003. Some were given standard acupuncture treatments, while others were administered something that resembled acupuncture but was not: The needles were inserted not as deeply and not at regular acupuncture points on the body.

A third group in the study got no treatment at all but were told they were on a waiting list for the research.

The proportion of those who said their headaches were reduced by at least half was 51 percent in the acupuncture group, 53 percent in the sham treatment group and 15 percent among those waiting for treatment.

“We cannot be certain that the effects are only or mainly psychological although this might be an explanation,” Linde told Reuters in response to an e-mail query.

“There is, for example, evidence that expectancy modulates pain perception (not only reporting but true perception) and many patients in Germany have a very positive attitude toward acupuncture (and our study patients clearly had),” he added.

But repeatedly sticking needles into the skin can possibly affect “pain memory,” he said, so it could be a mixture of psychological and physical factors.

Studies indicate that about 7 percent of men and up to 18 percent of women suffer migraines.