Neuro Clues to the Mysteries of Acupuncture

Advanced imaging methods may reveal how this ancient healing technique affects the brain.

Some people think of acupuncture as a wacky Eastern medicine, without any basis in science, while others consider it to be a crucial alternative to pain-relief medicine. Whatever the perspective, acupuncture use in the United States is on the rise, and the medical establishment has been taking notice. Now scientists are using advanced brain-imaging techniques to study the ancient practice -- and have begun to uncover some tantalizing clues about how it works.

Acupuncture is the 2,000-year-old practice of sticking extremely thin needles into the skin at specific points on the body, to try to control a range of symptoms, including pain, allergies, and infertility. While its effectiveness is still under debate, some large-scale clinical trials suggest that the technique can effectively relieve pain.

Two large controlled trials of acupuncture for osteoarthritis pain, published in 2004 and 2005, found that the practice is more effective than a sham treatment. Another study, published in the New England Journal of Medicine in 2005, found acupuncture to be effective for migraines; however, patients experienced the same level of pain relief regardless of whether needles were placed in traditional acupuncture points or other spots.

"Acupuncture has been shown to have some therapeutic effect, but we have an incomplete understanding of the basic science that supports it," says Bruce Rosen, director of the Martinos Center for Biomedical Imaging, within the Harvard-MIT division of Health Sciences and Technology. Rosen and colleagues are part of a small number of scientists using brain-imaging techniques to understand what acupuncture does to the brain, as well as which characteristics, such as needle placement, are important for beneficial effects.

Rosen's team at the Martinos Center is funded in part by a $5.9 million grant to study the neurological basis of acupuncture from the National Center for Complementary and Alternative Medicine (NCCAM), a division of the National Institutes of Health in Bethesda, MD, whose mission is to rigorously test commonly used alternative therapies.

The team has shown that acupuncture affects regions of the brain involved with sensory processing, as well as with cognitive and emotional processing. For example, Kathleen Hui, an instructor at Harvard Medical School and a member of the Martinos team, has shown that acupuncture induces a characteristic activity pattern in the brain. Using functional magnetic resonance imaging, which measures brain activation, scientists found that parts of the limbic system, a brain area involved in emotion, motivation, and memory, and parts of the cortex, involved in cognitive processing, seem to quiet down during acupuncture. These areas become active when a person is focused on performing a task, suggesting that acupuncture might affect some homeostatic mechanism involved in the brain's resting state, says Rosen.