JET LAG STUDY CASTS DOUBT ON MELATONIN
The dietary supplement melatonin became popular as a remedy for jet lag after several studies suggested it could help reset the body's biological clock in travelers who have crossed multiple time zones.
But a new study has found that melatonin performed no better than a placebo for alleviating jet lag symptoms--much to the surprise of the scientists conducting it.
"I am so puzzled. We had expected positive results," said Robert L. Spitzer, chief of biometrics at the New York State Psychiatric Institute. "I personally have stopped taking melatonin."
The body's manufacture of melatonin, a hormone made by the brain's pineal gland, is at peak levels during the night and shuts down in response to bright light. Thus, melatonin serves to synchronize body functions with the light/dark cycle. Previous studies had found that people who took melatonin at bedtime for several days after traveling suffered less severe jet lag.
Spitzer and several colleagues decided to compare three different dosage regimens of melatonin with a placebo in a group of 257 Norwegian doctors who were flying to Oslo from New York.
Researchers measured jet lag severity by questioning the subjects daily about nine common symptoms: fatigue, daytime sleepiness, impaired concentration, decreased alertness, trouble with memory, clumsiness, weakness, lethargy and lightheadedness. Ratings were done on the day of travel and for the next six days.
The results showed a marked increase in symptoms on the first day after arrival, with 63 percent of the doctors reporting at least moderate jet lag. Thereafter, symptoms improved steadily in all participants, with no significant difference among the four treatment groups. "We looked in vain for a subgroup that might show a positive result" with melatonin, Spitzer said.
He suggested that the apparent effectiveness of melatonin in previous studies may have represented a "placebo effect," in which participants respond favorably because they believe they are getting a treatment that will help them.
The study appears in the September issue of the American Journal of Psychiatry.
ASPIRIN LINKED TO LOWER--AND HIGHER--STROKE RISK
Up to an aspirin a day may help prevent one kind of stroke in healthy middle-age women, a study of nearly 80,000 women suggests, but the finding comes with an important caveat: Women taking higher doses--more than 15 tablets a week--doubled their risk of another type of stroke.
The lead researcher, JoAnn E. Manson, professor of medicine at Harvard Medical School, described the findings as "a good news, bad news situation."
There are two main forms of stroke. Ischemic stroke, the most common type, is caused by blood clots or other blockages in the arteries that lead to the brain. A less common but more often fatal type of stroke, hemorrhagic stroke, occurs when one or more blood vessels in the brain rupture.
In the latest study, the risk of having any kind of stroke fell slightly in women who took one to six aspirin a week and rose slightly in those who took seven or more a week. In particular, women who averaged one to six aspirin a week lowered their risk of a type of ischemic stroke caused by blockages in the large arteries in the brain.
But higher doses can cause trouble. The risk of hemorrhagic stroke not only doubled in healthy middle-aged women who took more than 15 aspirin a week, but tripled in older women with high blood pressure who took similar amounts.
The study is based on data collected in the Nurses' Health Study from 1980 and 1994. Researchers analyzed the link between aspirin use and stroke risk in 79,319 healthy middle-aged women.
Previous research has found that daily aspirin use can help prevent recurrences of heart attack or stroke, but it is still not clear if healthy people with no history of cardiovascular disease should take aspirin to prevent a first heart attack or stroke.
The study was conducted by researchers from Harvard Medical School and Brigham and Women's Hospital in Boston. Their findings appeared last week in Stroke, a journal of the American Heart Association.
STUDY FINDS MEN UNAWARE OF PROSTATE TEST'S RISKS
Blood screening tests for prostate cancer have become commonplace in recent years and are promoted by a number of medical groups. But some experts have questioned the practice, arguing that since prostate cancer is often very slow-growing and may not cause death, such tests can sometimes lead to treatment that may not be necessary and can be harmful.
Explaining this conundrum to patients has always been difficult, and medical groups have urged that men understand the issue before undergoing the screening exams. A study published this month, however, found that a large number of men who received the prostate-specific antigen (PSA) screening at the Veterans Administration Connecticut Health Care System in West Haven often don't know much about the test and afterward have no understanding of its risks or benefits.
The researchers, led by Daniel G. Federman, a staff physician at the VA facility, sent questionnaires to patients about three months after they received a PSA test. They analyzed the responses of 173 patients, whose median age was 69 years.
Nearly a third of the men said they were unaware that they had undergone a PSA test, while another 37 percent said they knew they had the test but did not remember having a discussion with their doctor about it. Of those who realized they had had the test, only 47 percent said they could remember talking to their physician about the impact of the test. The researchers report that some patients identified through a PSA test as having cancer may have "clinically indolent tumors" that they are "destined to die with--not of." Yet many of these patients will opt for treatment that will produce complications, "including pain, psychological trauma, impotence, incontinence and sometimes death."
"Although the goal of obtaining verbal informed consent is attractive in theory, we found its use to be limited in practice," the researchers wrote in the July/August issue of Effective Clinical Practice, published by the American College of Physicians and the American Society of Internal Medicine.