Millions of Americans turn to acupuncture each year to treat chronic pains and even depression. Recently, researchers at Rutgers University reported that combining the acupuncturist’s needle with an electric current could yield a new treatment for severe inflammation. Yet many scientists look skeptically at the practice.

There may not be a clear verdict yet but Scientific American MIND has brought together several experts to share their views. These include acupuncturist Hugh MacPherson, senior research fellow at the University of York in England; Edzard Ernst, emeritus professor of complementary medicineat the University of Exeter; Shu-Ming Wang of the Department of Anesthesiology and Perioperative Care at the University of California, Irvine, School of Medicine; pharmacologist David Colquhoun at University College London, also author of the blog DC’s Improbable Science; and Harriet Hall, a retired family physician and U.S. Air Force flight surgeon who writes the SkepDoc column in Skeptic magazine.

What’s your opinion on the evidence for acupuncture’s effectiveness in medicine and specifically depression?

MacPherson: Strong evidence exists that acupuncture is effective for chronic pain conditions. For depression, we have evidence that acupuncture is a useful adjunct to conventional care. In one recent trial patients on antidepressants who received acupuncture did significantly better than those who just took medication. Patients who received counseling in addition to their medication received a similar benefit to the acupuncture group.

Ernst: Most studies examining the effectiveness of acupuncture are not rigorous. Those that are more rigorous fail to show that acupuncture is more than a placebo in managing depression.

Wang: My opinion is that acupuncture stimulations trigger the release of beneficial hormones and, theoretically, can serve as a mood stabilizer.

Colquhoun: Acupuncture does not work, which means all discussions of how it does work are irrelevant. I’m not aware of any evidence that acupuncture works for depression.

Hall: The published evidence on acupuncture indicates that it might be helpful for pain and possibly for postoperative nausea and vomiting, but not for any other indications. All the evidence is compatible with the hypothesis that acupuncture is no more than a placebo.

Why is it so hard to figure out whether acupuncture works or not?

MacPherson: Trials on acupuncture involve a lot of variability, especially in relation to depression, which is unlikely to be a single disease entity. Depression is commonly experienced with other symptoms. For example, the population of patients with depression we recruited in one study included around 50 percent in chronic pain. This variability creates what we could call “noise,” making it more difficult to see whether an intervention works. The benefit one can ascribe to the placebo effect is not an important clinical question because in the real world patients benefit from simply consulting an acupuncturist.

Ernst: Studies are fraught with methodological problems such as finding a good placebo as well as logistical obstacles such as finding funding to conduct high-quality trials.

Wang: There are various stimulating techniques, follow-up period and study designs used by the researchers in clinical trials; thus, when we lump all the data from one illness, the significance may not be there. Furthermore, the belief of the participants significantly affects the results of the intervention.

Colquhoun: There is a lot of money at stake for those who sell acupuncture—and a certain amount of fascination with New Age thinking. There are excellent controls such as retractable needles. Almost all experiments show no difference between real and sham acupuncture.

Hall: Researcher bias tends to intrude because acupuncturists are the ones providing the therapy. Patients who don’t believe in acupuncture are not likely to volunteer for an acupuncture study; those who accept the possibility that acupuncture will work may be biased. Also, the very nature of acupuncture insures that there will be a strong placebo component and it is impossible to do double-blind studies. For instance, patients will notice if you stick needles in them and acupuncturists know whether they are doing sham or real acupuncture.

Why would targeting the body with a physical intervention help depression?

MacPherson: Acupuncture is a mind–body intervention. It does not just target physical symptoms. One of the reasons acupuncture may have a useful role for depression is that depression is experienced physically and emotionally. An intervention that incorporates an integrated approach to mental and physical symptoms would appear appropriate and, according to our depression trial, also evidenced-based.

Ernst: One theory holds that acupuncture increases endorphin levels in the brain. If this were true, it might help explain how acupuncture reduces depression.

Wang: Similar to physical activities, acupuncture can improve depression. It also has hormonal effects.

Colquhoun: Nobody has the slightest idea what causes depression. Experiments find acupuncture doesn’t work any better than a control situation, at least not to any extent that a patient would notice.

Hall: In studies of depression any intervention may be helpful, even talking with a friend, so it is difficult to tease out the specific contribution of acupuncture. There appears to be no specific effect of the needles, only nonspecific treatment effects. For instance, patients get to relax for half an hour or so with personal, hands-on attention by someone who is convinced he or she is helping.