News

Stents may seem like rather mundane medical devices. But these tiny wire-mesh tubes, which prop open blocked blood vessels to help prevent heart attacks, have ballooned into a multibillion-dollar industry.

Even so, the medical community is deeply divided over which stents work best. The scientific literature is filled with contradictory studies, some of which suggest certain stents may do harm.

And the picture is further muddied by what is absent from the literature: Most of the published studies do not disclose whether the researchers have financial ties to stent manufacturers - a factor that may bias their interpretation of the scientific data.

Kevin Weinfurt at the Duke Clinical Research Institute in Durham, N.C., decided to investigate the lack of financial disclosure.

He and his colleagues tracked down every scientific article written about stents in 2006. They found 746 articles written by 2,985 authors in 135 journals. About 83 per cent of those articles did not contain any disclosure statement at all, according to their findings published in the online journal PLoS One.

"We actually did our own, informal Internet search on authors who expressly stated that they had no interests to disclose and found that some of them held membership on stent manufacturers' advisory boards or were consultants for stent makers and companies that made drugs related to stent use," Dr. Weinfurt said in a statement released with his study.

"One person had even founded a company that makes stents and yet had not disclosed that information."

Dr. Weinfurt said he can't be sure whether some authors are deliberately keeping their corporate ties secret, or whether a majority of journals just are not asking relevant questions. Whatever the case, the hidden ties between researchers and industry threaten to undermine public trust in the medical literature, he said in an interview.

Alzheimer's shield?

Patients who take the pain-relieving medication ibuprofen for prolonged periods appear to be at a lower risk of developing Alzheimer's disease, according to new research.

The study, published in the journal Neurology, involved nearly 250,000 U.S. military veterans over the age of 55. The results showed that people who used ibuprofen for more than five years were 40 per cent less likely to develop the mind-robbing disease, compared with those who did not routinely take the common pain medication.

The researchers stressed that their study does not prove ibuprofen guards against Alzheimer's. It's possible that the people who took the drug shared some other trait that provided a shield against the illness.

What's more, healthy people shouldn't start taking these pills in the hopes of preventing dementia. Ibuprofen, sold under a variety of brand names such as Advil and Motrin, can cause serious side effects including gastrointestinal bleeding. "Using ibuprofen for [Alzheimer's disease] protection is premature at this point and could cause more harm than good," lead researcher Steven Vlad at Boston University's school of medicine, said in an e-mail.

Still, he hopes the study will stir up interest in a large trial that could clarify ibuprofen's potential benefits.

The sunshine vitamin

Dutch researchers have discovered a link between depression and low levels of vitamin D.

Blood levels of vitamin D were 14 per cent lower in patients with major and minor depression compared with non-depressed participants in the study group, which included 1,282 seniors aged 65 to 95.

Vitamin D is produced naturally in human skin as a result of exposure to sunlight. It is also found in certain foods and supplements.

The researchers don't yet know whether the low levels of vitamin D are "a cause or a consequence of depression," they write in the journal Archives of General Psychiatry. "That is the next thing we will look at - to see what comes first," said lead researcher Witte Hoogendijk at VU University's medical centre in Amsterdam.

"And if, indeed, vitamin D is causal for depression, then we will be able to advise potential patients to go outside more or give them vitamin D tablets."

Vitamin D may also have a role to play in seasonal affective disorder, which is essentially the winter blues. SAD is thought to be caused by reduced exposure to sunlight during winter months. It is often treated by having a patient look into a special light box that is believed to reset the body's internal clock through the optic nerve.

Dr. Hoogendijk noted there are vitamin D receptors in the brain, especially near the area where the body's biological clock is located.

"So, it may be that the biological clock receives two inputs," one from light striking the eye and one from vitamin D produced in the skin, Dr. Hoogendijk said. Menopause test

A simple blood test may determine when a woman will go through menopause, researchers report.

On average, women reach menopause by the age of 51, marking the end of the reproductive phase of life.

But, of course, there is a lot of individual variation. And the ability to become pregnant becomes extremely difficult a full decade before menopause.

"A test predicting menopause and sub-fertility might be very useful for women planning to postpone childbearing, for example, to pursue a career," said one of the researchers, Jeroen van Disseldorp of the University Medical Centre Utrecht in the Netherlands.

The test measures anti-Müllerian hormone, or AMH, which is released by egg follicles, fluid-filled sacs located in the ovaries. A woman is born with about 3 million follicles which contain immature eggs. Every month, a bunch of eggs mature and the follicles that produced them die off. By the time she reaches menopause only 1,000 follicles remain.

Blood levels of AMH gradually decrease along with the dwindling supply of follicles. So, this measure can be used as a marker for declining fertility, said Dr. van Disseldorp.

"We already knew it had a relationship with menopause. But we didn't know what was low for a certain age group," said Dr. van Disseldorp.

To find out, the researchers measured AMH in 144 healthy fertile women and used this information to estimate average levels of the hormone for certain ages.

More research is needed to confirm the figures. But if a women is below average, she may not want to unduly delay pregnancy, he said.

ptaylor@globeandmail.com