Posted: 10 October 2011
PARIS: If you are always seeing the light at the end of the tunnel, be warned -- it could be an oncoming train.
So says a study published Sunday in Nature Neuroscience which concludes that our well-known penchant for donning rose-tinted glasses may be a failure to store risk awareness in a key part of the brain.
Tali Sharot, a professor at University College London, was intrigued as to why so many people -- even when facing long odds or bleak prospects -- remain stubbornly, even pathologically, optimistic.
To learn more, 19 volunteers were asked to take part in an experiment.
Sharot and colleagues monitored subjects in a functional magnetic resonance imaging (fMRI) scanner as they were confronted with life situations ranging from unpleasant to catastrophic.
Having their car stolen, getting fired from their job, developing Parkinson's disease or cancer were among 80 scenarios evoked.
After each hypothetical disaster, the volunteers were asked to estimate the odds of the misfortune happening to them. While still in the scanner, they were then informed of the true average probability of the risk.
Sometime later, the volunteers once again quantified the odds for personally experiencing each scenario.
The researchers found that the volunteers updated their initial estimates -- but only when the true figures were less gloomy.
If, for example, they had predicted a 40 percent chance of contracting cancer but the average likelihood turned out to be 30 percent, they were far more likely to adjust their estimate sharply downward.
But if the odds were worse than originally thought, the volunteers simply ignored the true statistics.
"Our study suggests that we pick and choose the information that we listen too," said Sharot.
"The more optimistic we are, the less likely we are to be influenced by negative information about the future," said Sharot.
Why so?
In the brain scans, all participants showed increased activity in their frontal lobes -- which is strongly associated with emotional control -- whenever the real numbers were better than expected.
The activity indicated that the new information was being processed and stored.
But when the news was more dire than the first guesstimate, respondents who had rated highest for "optimism" in a personality test, taken beforehand, showed the least activity in their frontal lobe.
Sharot said the work showed that unbridled optimism had unperceived risks.
"Seeing the glass as half full rather than half empty can be a positive thing -- it can lower stress and anxiety, and be good for our health and well-being," she said.
"But it can also mean that we are less likely to take precautionary action, such as practising safe sex or saving up for retirement," she said.
Many experts, she pointed out, believe that the financial crisis that began in the fall of 2008 was in large part caused by wishful thinking about rising property values and the ability to play down or dismiss levels of debt.
-AFP/vl
Taken from ChannelNewsAsia.com; source article is below:
Look on bright side, not such a bright idea
Posted: 04 October 2011
PARIS: Women who use hormonal birth control are roughly twice as likely to become infected with HIV or pass on the AIDS virus to their partner, according to a study published on Tuesday.
The research was carried out among 3,790 heterosexual couples in Africa where one partner had the human immunodeficiency virus (HIV) while the other was uninfected.
The findings, if confirmed, could have huge repercussions for policies on contraception and HIV prevention.
The authors say it strengthens the need for safe-sex messages, in which the condom is promoted as a shield against the AIDS pathogen.
The couples were monitored for an average of 18 months during which 167 individuals became infected, 73 of them women, according to the paper appearing in The Lancet Infectious Diseases.
Transcribed into a benchmark of prevalence, HIV transmissions were 6.61 per 100 person-years in couples where women used hormonal contraception, compared to 3.78 per 100 person-years among those who did not.
Rates of infection from women to men were 2.61 per 100 person-years among women who used hormonal contraception, but 1.51 per 100 person-years among those who did not.
Most of the women who took hormone contraceptives used an injectable, long-lasting form such as the Depo-Provera shot. Only a small number used the Pill; in this group, there was an increase in HIV risk but not big enough to be conclusive.
Over the last two decades, scientists have launched several investigations into whether hormonal contraceptive use affects HIV risk, but the probes have returned conflicting results.
This is the first large-scale study, using an ambitious design, to return clear proof of the risk. It is also the first to highlight an apparent risk to men.
The investigators noted that women who took injectable contraceptives had "raised concentrations" of HIV genetic material in their cervical secretions.
If this is a mechanism for handing on the virus to men, further work is urgently needed to test the theory, they said.
In practical terms, doctors should advise women of the potentially increased risk and warn them of "dual protection" with condoms, says the probe, led by Renee Heffron of the University of Washington in Seattle.
The study was conducted between 2004 and 2010 in Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia as part of a trial of a therapy against the herpes simplex virus, which is common among people with HIV.
In a commentary also carried by the journal, clinical scientist Charles Morrison spoke of a "tragic" dilemma.
Promoting hormonal birth control in Africa could be contributing to the HIV epidemic; yet limiting this highly effective form of contraception would also boost rates of maternal death and sickness, underweight babies and orphans.
"The time to provide a more definitive answer to this critical public health question is now," through a randomised trial of volunteers, he wrote.
In 2009, more than 33 million people were living with HIV and 2.6 million people became newly infected, according to figures released last year by UNAIDS.
- AFP/de
Taken from ChannelNewsAsia.com; source article is below:
Female hormonal contraception linked to higher HIV risk
