| Groups of friends key to changing health behaviors Fri 3rd September 2010 | CHICAGO (Reuters) - When it comes to changing health behaviors, it takes more than a far-flung network of friends on Facebook egging you on. It takes a jostling herd, U.S. researchers said on Thursday.
Social scientists have assumed that changing behavior would spread like the flu, which transmits best via individuals with lots of long-distance contacts.
But to change behavior, you need to be surrounded by the message -- with neighbors, family and members in the community all reinforcing the same idea.
"For about 35 years, wisdom in the social sciences has been that the more long ties there are in a network, the faster a thing will spread," Dan Centola of the Massachusetts Institute of Technology, whose study appears in the journal Science, said in a statement.
"It's startling to see that this is not always the case."
Knowing how best to influence health behavior is important to health reform as the United States turns its focus to preventing disease, rather than treating it.
Researchers have already shown that networks of friends can have a powerful impact on health behavior, influencing smoking, obesity and even happiness.
But it is not clear which type of network is best.
SOCIAL PETRI DISH
Centola set up two different types of social networks within an online community of about 1,500 people.
"I had to create a little social petri dish," Centola said in a telephone interview.
One group consisted of individuals with far-flung ties, and the other involved clusters of people who interacted with each other.
"When people signed up, I would assign them 'health buddies' in the space of this online social networking site," Centola said. To form friendship groups, Centola introduced people to six other people who had similar interests.
"That is the social world that you had," he said.
The goal was to get people to register for a health forum in which they rated different health services.
The team then seeded the groups with people to encourage them to sign up, and they watched to see how quickly people would register.
People in the small friend groups registered four times as fast as those with less connected networks.
"It spread through the population so quickly. It saturates very, very fast," Centola said.
Social scientists had thought that it would be redundant to give a health message to a person more than once. But Centola said when it comes to health habits, people are quicker to change when they hear the message from more than one source.
He said the findings are useful when policymakers need to develop strategies to promote vaccinations or health screenings, but it could be equally effective in combating obesity.
"The more difficult the behavior and the more resistant to change, the more vital these densely clustered ties would be," Centola said.
Source: Reuters
| | Diabetes drug might fight cancer Fri 3rd September 2010 | In use for years, metformin has few side effects
An ancient herbal remedy that constitutes the active ingredient in a modern diabetes drug may soon play a new role in combating cancer, two studies show. The findings, published in the September Cancer Prevention Research, support earlier population studies suggesting that diabetes patients receiving the drug, called metformin, are less prone to develop cancer.
Metformin helps to stabilize blood sugar by decreasing the liver’s glucose output and increasing the sugar’s use by muscle tissue. Scott Lippman, an oncologist at the University of Texas M.D. Anderson Cancer Center in Houston, estimates that more than 40 million metformin prescriptions have been filled in the United States. “It’s been around for a while,” he says.
In one of the new studies, Atsushi Nakajima of Yokohama City University School of Medicine in Japan and colleagues measured how metformin affected the development of tiny lesions in the colon. These lesions, called aberrant crypt foci, are precursors of polyps, which themselves can be the forerunners of colon cancer. Using colonoscopy data, the scientists identified 26 patients who had had polyps removed during a colonoscopy. The scientists randomly assigned some to get metformin and others to get a placebo.
After a month, the nine patients getting metformin who returned for a follow-up colonoscopy had substantially fewer lesions in the bowel than they had when they started on the drug, whereas 14 patients receiving a placebo had no change.
In the other study, a U.S. team induced lung cancer in mice with injections of a tobacco-based carcinogen. One week after the last shot, some mice were given either a low or a medium dose of metformin in their drinking water for 13 weeks. The tumor burden in these mice declined by 39 percent and 53 percent over that time, depending on the dose they received.
When the researchers delivered an even higher dose of metformin, this time by injection, the tumor burden shrank by 72 percent, says study coauthor Phillip Dennis of the National Cancer Institute in Bethesda, Md.
Metformin is a drug in the biguanide class. The drug is derived from the French lilac plant (Galega officinalis), also known as goat’s rue or Italian fitch. In medieval Europe the plant was used to treat frequent urination, says Michael Pollak, an oncologist at McGill University in Montreal. Modern-era scientists took an interest in the biguanides in the 1920s, and found they could use the compounds to lower blood sugar in rabbits.
Metformin was derived from the plant in the 1950s in France and was approved by the U.S. Food and Drug Administration in 1994 as Glucophage (literally “glucose eater”). The drug has since become generically available under the name metformin.
A history of use with few side effects may help metformin as it faces regulatory hurdles to become a cancer fighter, Lippman says. “A lot is known about the safety of this,” he says. “From a research perspective, this is extremely exciting. The next step will be to take it to a clinical trial.”
Less clear is the mechanism by which metformin seems to inhibit cancer, and which cancers would be most susceptible if it succeeds. Earlier, Pollak’s team had shown that metformin could inhibit growth of breast cancer cells in a lab dish by awakening an enzyme called AMPK. The group further found that revved-up AMPK inhibits the activity of mTOR — a protein involved in cell growth and proliferation. That could explain part of metformin’s apparent anticancer effect, Pollak says. But, he adds, “We are not yet in a position where we understand perfectly how it works.”
The cancer connection didn’t come out of the blue. In recent years, several population studies have noted that type 2 diabetes patients on metformin seem less likely than others to develop cancer.
Source: Science News
| | Puzzles and crosswords delay dementia, study suggests Fri 3rd September 2010 | People who do puzzles and crosswords may stave off dementia longer but experience a more rapid decline once the disease sets in, a study suggests.
While there has long been speculation that "exercising" your brain could protect against Alzheimer's, there has been little evidence to back this up.
Now US researchers who followed more than 1,000 people suggest the more mentally active may delay the disease.
But once symptoms appeared, decline was quicker, the research suggested.
The team from the Rush University Medical Center in Chicago recruited 1,157 people aged over 65 in the early 1990s.
They were given a maximum of five points based on how often they engaged in a variety of activities which involved processing information, including listening to the radio or watching TV, reading a book, carrying out a crossword puzzle or jigsaw, or going to a museum.
Slowing down, speeding up
They were then followed for an average of 12 years, with assessments every three years.
For each additional point those without a diagnosed cognitive impairment saw a 50% slower decline in their brain function, which was examined through a variety of tests.
But the 148 people who had a diagnosis of Alzheimer's saw a 42% faster decline for each point they had accumulated for mental activity.
Writing in the journal Neurology, the authors suggest that cognitive activity enhances the brain's ability to maintain normal function as disease develops, allowing the mind to tolerate significant pathological changes without compromising its performance.
But when Alzheimer's is finally diagnosed, the disease appears to be at a more advanced stage.
"In effect, these results suggest that the benefit of delaying the initial appearance of cognitive impairment comes at the cost of more rapid dementia progression," says study author Dr Robert Wilson.
It does however, he added "reduce the overall amount of time that a person may suffer from dementia".
The Alzheimer's Society said this was a "robust study" which added considerable weight to the argument that, at least in later life, activities like puzzles could keep the brain ticking over for longer.
"However although the symptoms are delayed, there is no evidence changes in the brain associated with dementia have been reduced," a spokesperson said.
"That the brain is allowed to deteriorate to a larger degree before symptoms like memory loss become apparent could explain why the condition seems to progress more quickly after diagnosis.
"More research is now needed to establish why this happens and what role mental stimulation may have in keeping people functioning for longer.'"
Source: BBC
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