Patients have long reported that acupuncture helps relieve their pain, but scientists don't know why. Could it be an illusion? Now brain imaging technology has indicated that the perception of pain relief is accurate.

Using functional magnetic resonance imaging (fMRI), researchers at the University of Medicine and Dentistry of New Jersey (UMDNJ) in Newark found markedly decreased brain activity in nine of 12 volunteers who were exposed to pain and also given acupuncture. The decreased brain activity, the researchers said, indicated that the people were feeling less pain.

"This is scientific evidence of a response people have been getting for 2,500 years," said Huey-Jen Lee, chief of neuro-radiology at UMDNJ. "Western doctors have been reluctant to use acupuncture for pain relief because they did not know why it was effective. Now we are learning more about the physical response created by acupuncture."

In the Eastern tradition of acupuncture, there are 401 identified "acupoints," where the insertion of a hair-thin acupuncture needle or electric needle stimulation can create sensations elsewhere in the body. In this study, researchers used only the "Hegu" acupoint, between the thumb and forefinger.

In the study, presented at a meeting of the Radiological Society of North America last week, the baseline pain threshold of 12 subjects was measured by inducing light pain to the inside or outside of the upper lip. In all study participants, the pain resulted in a significant increase in brain activity as measured by the fMRI. But that brain activity--an increased flow of blood and use of oxygen--sharply decreased for most of the people in the study after acupuncture was applied.

Lee said that while there was a consistent decrease in brain activity after acupuncture, the decrease did not always show up in the same parts of the brain. This finding was in line with previous work showing that individuals experience pain quite differently, and that emotions play a role in determining how an individual will respond and what areas of the brain will be involved. The relationship between which parts of the brain are activated and how pain is perceived is not yet well understood.

Lee, who studied acupuncture in his native Taiwan, said he hoped the procedure could gradually become a mainstream complement to pain medication and perhaps ultimately a substitute. Lee said acupuncture offers some advantages over aspirin, morphine and other Western pain medications because it has no side effects, is not addictive and can last for weeks.

--Marc Kaufman


Women who gain weight after their 18th birthday are more likely to develop asthma as adults than those who do not, according to a study of more than 85,000 registered nurses conducted by researchers at the Harvard School of Public Health.

The finding, published in the Nov. 22 issue of the Archives of Internal Medicine, suggests that the twin epidemics of adult asthma and obesity may be related. The prevalence of asthma, which affects about 7 percent of the population, has risen steadily in the past 20 years in developed countries for unexplained reasons. Rates of obesity also have skyrocketed during the same period: 55 percent of Americans are currently considered to be overweight, about one-third of them obese.

As part of their ongoing study, which examines the relationship of diet and lifestyle to the development of breast cancer and other diseases, Harvard researchers surveyed nearly 117,000 female nurses in 14 states who were between the ages of 24 and 44 when the project was launched in 1989.

Women who gained about 50 pounds were five times as likely to develop asthma compared with those with stable weight.

The mechanism by which obesity might trigger adult-onset asthma is unclear, researchers reported, but the condition may arise from reductions in airflow or from gastroesophageal reflux disease. Reflux, the regurgitation of acid into the esophagus from the stomach, is a risk factor for adult-onset asthma.

"The results are consistent with . . . reports that individuals with asthma tend to weigh more than those without asthma and that obesity may have an adverse effect on pulmonary function," the authors noted.

But in a companion editorial, pulmonologists Mark M. Wilson and Richard S. Irwin of the University of Massachusetts Medical School expressed skepticism about a link between adult asthma and obesity. The lung specialists suggested that the two conditions may simply reflect an increase in two common conditions.

--Sandra G. Boodman


Children exposed to moderately high levels of electromagnetic radiation--from such sources as household wiring, high-voltage power lines and home appliances--did not show increased rates of cancer compared with children who had less exposure, according to a large British study.

The new findings echo the generally reassuring results of several other recent studies that have also failed to confirm a link between childhood exposure to electromagnetic fields (EMFs) and cancer. Such a link, particularly between EMF exposure and leukemia, had been suggested by some earlier research.

The British study's authors caution that it didn't contain enough children at high levels of EMF exposure--above 2 milligauss--to conclude that such levels don't affect cancer risk. (A milligauss is a unit used to measure magnetic field strength.) However, high levels of EMF exposure are uncommon in the general population, said Sir Richard Doll, an emeritus professor of medicine at the University of Oxford, who helped direct the British study.

Researchers from the UK Childhood Cancer Study enrolled 2,226 children with cancer in England, Wales and Scotland and matched them with a control group of healthy children. They asked parents of participants about possible EMF exposure from power lines, heating systems, electric blankets and other sources. They also measured EMFs in the children's homes, schools and even on their beds and pillows. They then estimated each cancer patient's total EMF exposure in the year preceding diagnosis and compared it with the estimated EMF exposure of the matched control.

The levels of past EMF exposure in the children with cancer were not significantly different from those in the healthy children. There was no evidence that EMF exposure increased the risk of leukemia, brain tumors or cancer in general.

The study was published last week in The Lancet. An accompanying commentary, by Michael H. Repacholi and Anders Ahlbom of the World Health Organization, notes that a forthcoming Japanese study may provide more information on children with high levels of EMF exposure.

--Susan Okie