TUESDAY, Feb. 26 (HealthDay News) -- While popular antidepressants such as Prozac are widely prescribed for people with varying degrees of depression, the drugs are only effective for those with the most severe depression, a new study suggests.

"Although patients get better when they take antidepressants, they also get better when they take a placebo, and the difference in improvement is not very great," lead researcher Irving Kirsch, a professor of psychology at the University of Hull in Great Britain, said in a prepared statement. "This means that depressed people can improve without chemical treatments," he added.

In the study, Kirsch and his colleagues collected data on 35 clinical trials of drugs called selective serotonin reuptake inhibitors, or SSRIs, whose results had been submitted to the U.S. Food and Drug Administration. The antidepressants included in the trials were fluoxetine (Prozac), venlafaxine (Effexor), nefazodone (Serzone), and paroxetine (Seroxat/Paxil).

An analysis of the data showed that patients taking antidepressants fared no better than patients receiving a placebo. This appeared to be the case whether the patients were mildly or moderately depressed.

The drugs only seemed to benefit a small group of patients -- those with the severest depression when the study began.

Based on these results, there appears to be little reason to prescribe these antidepressants to anyone but the most severely depressed patients, the study authors concluded.

The findings were published online Feb. 25 in the journal PLoS Medicine.

Dr. Nada Stotland, president-elect of the American Psychiatric Association, said she wasn't surprised that the study found that not every antidepressant works for every patient. Many people who are depressed don't respond to the first antidepressant they try. It can take up to an average of three different antidepressants until one works for a particular patient, she said.

"Medication helps some, but not all, people with depression," Stotland said in a prepared statement. "For people with mild to moderate depression, psychotherapy can work as well as medication. Studies have shown that between 70 and 80 percent of people can and do get better with a combination of treatment approaches, which will often include individual therapy, family therapy and/or medication.

"Therefore, testing any single antidepressant on a group of depressed individuals will show that many of them do not improve," Stotland added. "There is a small group of depressed individuals who do not respond to any antidepressant."

The new study highlights the fact that treatment for depression needs to be tailored to an individual, and that the most effective treatment will often include multiple approaches, Stotland said. The study results also suggest that more long-term follow-up trials are needed to determine which patients are most likely to benefit from specific therapies.

"Some of the most exciting research in progress at the present time concerns our attempt to match the antidepressant to the patient from the outset; we may be able to perform laboratory tests or identify clinical factors that let us know in advance which antidepressant will work for each person," Stotland said. "That will be an enormous advance for the millions of people suffering from this very painful and potentially disabling disease."

In a prepared statement released late Tuesday, Pharmaceutical Research and Manufacturers of America (PhRMA) Senior Vice President Ken Johnson said, "It is true that pharmaceutical products, such as antidepressants, can result in a differential response among different patients. It is for this reason that a variety of therapeutic options is important in health care -- so that each patient can receive the most effective treatment for his or her needs.

"Because of this, America's pharmaceutical research companies are dedicated to continuing their research into and development of potential new medicines to treat depression as well as the other disease that affect patients worldwide."

More information

To learn more about antidepressants, visit the U.S. National Library of Medicine.

MONDAY, Feb. 25 (HealthDay News) -- The water you drink stays in your hair, and it may reveal details about where you've been, new research suggests.

By analyzing the makeup of water molecules from human hair, University of Utah scientists were able to roughly determine the regions where people recently lived. While the approach isn't always accurate, the researchers say it's correct about 85 percent of the time.

Although the discovery has some implications for medical research, its more immediate use might be in tracking the history of unidentified bodies and perhaps testing the alibis of criminal suspects. "The big picture is for us to provide a tool for law environment," said study author James Ehleringer, a University of Utah biology professor. "This is an attempt to really try to help."

According to Ehleringer, the researchers wondered about the potential secret history exposed by water after the anthrax attacks of 2001. "We began to ask whether microbes might record the water environment in which they were living," he said.

Water, after all, makes up a major chunk of the human body. It comes from not only the liquids that people drink but also the food they eat.

To figure out if they could detect a kind of fingerprint from water, the researchers extracted water molecules from protein in human hair. Then they broke the molecules apart and studied the concentration of heavy and light isotopes.

The study findings appear in this week's online issue of the Proceedings of the National Academy of Sciences.

The scientists found what they call an "isotopic fingerprint," a combination of the ratios of heavy and light isotopes in the hydrogen and oxygen of the water.

The fingerprints can give scientists a rough idea of where the water came from, depending on how heavy it is. This is not related to the more familiar concept of "soft" or "hard" water.

Due to variations in geography, water is heavier in some parts of the world than others, Ehleringer said. According to him, it's now possible to differentiate water that comes from different places.

The technique can't pinpoint an exact city or town, but can say whether water came from a kind of place, such as a coastal region, he said. "For instance, if you were to give me bottled water from Sacramento, California, and Denver, Colorado, I could easily tell them apart," using the technology, he said. "But I might not be able to tell apart something from Sacramento, California, versus Fresno, California. That might be too close a region."

And what about people who only drink bottled water that may come from far away? Unless they boil their potatoes and make their coffee and bottle their beer in the water, local water will still show up in their bodies, Ehleringer said.

The cost of the test is about $100, said Ehleringer, who works for a company promoting the technology.

According to the researchers, the technology could be used in medicine. Hair might indicate that someone such as a diabetic -- drinks a lot of water or could offer clues to someone's diet.

Law enforcement is already using the technology. In Utah, homicide detectives tested the hair of an unidentified murder victim and discovered that she probably moved around the Northwest in the two years before she died.

Next, the scientists are planning to figure out where she grew up by testing the water in her teeth. "I think you'll see this technology have an impact on (identifying) unidentified victims from around the country," said Todd Park, a Salt Lake County sheriff's homicide detective. "The more specific information I can get about my victim, the better the odds will be for me to find out who she is."

More information

Learn more about unidentified bodies from The Doe Network  .

THURSDAY, Feb. 21 (HealthDay News) -- In the largest such examination of human genetic diversity yet conducted, an international team of geneticists has used clues in DNA to track differences and similarities between people around the globe.

Reporting in the Feb. 22 issue of Science, a team led by Richard Myers, of Stanford University, looked at more than 650,000 variants in individual genes, called single-nucleotide polymorphisms (SNPs) found in 938 unrelated volunteers in countries around the world.

Among other findings, the new data support the notion that "a small group of individuals migrated out of eastern Africa and their descendants subsequently expanded into most of today's populations," the researchers wrote.

That expansion occurred mainly over the past 100,000 years, the team says. Using high-tech DNA analysis of the SNPs, they were able to determine the distinct genetic identities of eight European groups of modern humans, as well as four in the Middle East. They also believe that shared genes found among Native Americans and certain groups in Russia "reflects shared ancestry before the predecessors of the Native Americans crossed the Bering Strait."

The report in Science follows on the heels of similar international efforts by other researchers, reported in two studies published in the Feb. 21 issue of Nature.

Noah Rosenberg, co-senior author of one of two Nature studies, explained that his group has "investigated genetic similarities of populations across a very large number of sites in the human genome. We found that it's possible, with a high degree of accuracy, [to tell] which continent, in which population, the individual comes from."

In addition, the primary determinant of genetic similarities and differences seems to be geographic location, said Rosenberg, who is an assistant professor of human genetics at the University of Michigan. "The closer populations are, the greater the degree of similarity between the populations," he noted.

Rosenberg's team also found that the number of distinct genetic variants declined as the distance from Africa increased. "This suggests that a genetic history reflects a history in which populations migrated out of Africa, and along the way only a portion of the genetic diversity available migrated to the next location," he said.

There is still a great deal of genetic diversity in each population, Rosenberg pointed out.

In the study, Rosenberg's team looked at more than 500,000 DNA markers. The markers came from 485 volunteers in the Human Genome Diversity Project. Rosenberg's team looks at genetic variations in 29 different groups from Africa, Europe, the Middle East, Southeast Asia, the Pacific Ocean islands, and the Americas.

The implication of what Rosenberg's group found is that scientists now have a finer understanding of human evolutionary history.

"We can infer how our ancestors migrated across continents and became successful at living in a very diverse range of environments," Rosenberg said. "In addition, the genes are [a] database [that] can be used to search for disease genes in the human genome."

In the second Nature report, Carlos Bustamante, an assistant professor of biological statistics and computational biology at Cornell University, looked at DNA from European Americans and African Americans.

The researchers looked at 10,000 genes in 15 African Americans and 20 European Americans, all of whom were healthy.

"Across all the individuals, we found almost 40,000 DNA sites that varied. The African-American sample [had] more variations than the European-American sample, which is consistent with previous work showing higher levels of overall genetic diversity in African-Americans," Bustamante said.

This finding suggests that only a subset of diversity was present in the founding populations of Europe, Bustamante said, adding, "We refer to this as a population bottleneck."

Bustamante's team found that the proportion of mutations that are associated with risk for disease is higher in the European-American population. "This is consistent with evolutionary theory that mutations may undergo slightly relaxed natural selection in bottleneck populations," he said.

All the individuals in the study had about 400 mutations that may be linked to disease, Bustamante said.

How these mutations affect human health isn't known, Bustamante added. "Efforts to do sequencing to look at individuals [with] and without disease will likely find rare mutations that may be contributing to disease," he said.

Last month, it was announced that the genomes of 1,000 people worldwide will be mapped in what scientists are calling the most detailed and medically relevant look at human genetic variation ever conducted.

The 1,000 Genomes Project will receive major support from the U.S. National Human Genome Research Institute (NHGRI), the Wellcome Trust Sanger Institute in England, and the Beijing Genomics Institute in China.

"This new project will increase the sensitivity of disease discovery efforts across the genome fivefold and within gene regions at least 10-fold," NHGRI director Dr. Francis S. Collins said in a prepared statement.

More information

For more information on understanding the human genome, visit the Human Genome Project .

TUESDAY, Feb. 19 (HealthDay News) -- Borrowing a design from the agile, sticky-footed gecko, scientists have created a waterproof, biodegradable adhesive bandage that may one day replace conventional sutures.

The bandage, which could close external wounds and mend internal injuries, has tiny "hills and valleys," similar to those found on the gecko's feet, a Harvard-MIT team reports. This bit of natural engineering allows geckos to cling to almost any surface, even upside-down.

Overlaying the clingy structures is a coating of glue that enables the new bandage to stick onto wet tissues. That ability to stick in wet conditions has been a major challenge to overcome, the researchers said.

"There is a big need for bondable, tape-based adhesives that could be used to seal tissues," said lead researcher Jeffrey M. Karp, director of the Laboratory for Advanced Biomaterials and Stem Cell-Based Therapeutics at the Harvard-MIT Division of Health Sciences and Technology at Brigham and Women's Hospital in Boston.

His team described the new bandage in this week's online edition of the Proceedings of the National Academy of Sciences.

There are other glue-based surgical tapes available, but many are neither flexible nor waterproof, Karp noted. "We decided we needed to create a new material that was elastic, that could conform to the tissue and that could be biodegradable," he said. "So we created this new material that met all of these requirements."

To design a material that could adhere to slippery tissues, the researchers turned to one of nature's stickiest creatures, the gecko. The gecko is able to cling to walls and ceilings using tiny corrugated structures called "nanoscale pillars" on its paws.

"The gecko has no glue, but it uses nanoscale pillars -- a whole carpet of them, millions of them, to adhere to a surface," Karp said. "We decided we could incorporate nanostructures in the surface of our material to enhance the adhesion," he said.

According to the researchers, the new bandage is also biodegradable and dissolves over time, so it wouldn't have to be surgically removed. The amount of time the tape needs to biodegrade can be programmed for specific applications, Karp noted.

Ideally, this type of adhesive bandage should also prevent leaks and deliver drugs for long term, similar to a skin patch, Karp said. He envisions the new adhesive tape being used in hernia surgery, gastric bypass surgery, surgery to remove part of the colon in Crohn's disease and many other invasive procedures. The tape could also be used to seal holes in the bladder or holes caused by ulcers.

"In addition, we believe that these tapes can also be used as a general internal drug-delivery patch to deliver anti-inflammatories, antibiotics or growth factors to encourage healing," Karp said.

The new product could someday replace sutures or staples in some circumstances, such as minimally invasive surgery, Karp said. Because the tape can be folded and unfolded, it could be used in procedures that are difficult to suture because they are performed through a very small incision, he noted.

So far, Karp's team has demonstrated their tape on pig intestine and has implanted the product in the stomachs of rats. When used with pig intestine, the new tape was twice as strong as tape that did not have the nanoscale pillars. In rats, the new tape increased adhesive strength by 100 percent compared with material lacking the nanoscale pillars.

The researchers are now at the point of designing adhesives for specific tissues, because each tissue type is distinct, Karp said. They then hope to start testing the gecko-inspired adhesive in clinical trials.

More information

For more on sutures, visit the University of Illinois Medical Center  .