A new study has found that testosterone therapy does not increase men's risk for heart attack.

Jacques Baillargeon, lead author of the study said that their investigation was motivated by a growing concern, in the U.S. and internationally, that testosterone therapy increases men's risk for cardiovascular disease, specifically heart attack and stroke and added that there is a large body of evidence that is consistent with the findings of no increased risk of heart attack associated with testosterone use.

This University of Texas Medical Branch study of more than 25,000 older men shows that testosterone therapy was not associated with an increased risk of heart attack, whereas the testosterone users with a higher probability of cardiovascular problems had a lower rate of heart attacks in comparison to equivalent patients who did not receive testosterone therapy.

This study was published in the Annals of Pharmacotherapy.

Eating dark chocolate - a food rich in polyphenols - may help people with peripheral artery disease walk a little longer and farther before pain sets in, scientists have found.

In a small study, people with artery problems in their legs walked a little longer and farther when they ate dark chocolate.

Peripheral artery disease (PAD) is a narrowing of the peripheral arteries to the legs, stomach, arms, and head - most commonly in the arteries of the legs.

Reduced blood flow can cause pain, cramping or fatigue in the legs or hips while walking.

In the pilot study of patients with PAD (14 men and six women, ages 60-78), study participants increased their ability to walk unassisted after eating dark chocolate, compared to when they ate milk chocolate.

The authors suggest that compounds found in cocoa - polyphenols - may reduce oxidative stress and improve blood flow in peripheral arteries.

The patients were tested on a treadmill in the morning and again two hours after eating 40 grams of dark and milk chocolate (about the size of an average American plain chocolate bar) on separate days.

The dark chocolate in the study had a cocoa content of more than 85 per cent, making it rich in polyphenols. The milk chocolate, with a cocoa content below 30 per cent, had far fewer polyphenols.

After eating the dark chocolate, they walked an average 11 per cent farther and 15 per cent longer (almost 12 metres farther and about 17 seconds longer) than they could earlier that day. But distance and time didn't improve after eating milk chocolate.

The improvements were modest, but the benefit of dark chocolate polyphenols is "of potential relevance for the quality of life of these patients," said Lorenzo Loffredo, the study's co-author and assistant professor at the Sapienza University of Rome in Italy.

Levels of nitric oxide - a gas linked to improved blood flow - were higher when participants ate dark chocolate. Other biochemical signs of oxidative stress were also lower.

Based on these observations and other laboratory experiments, the authors suggest that the higher nitric oxide levels may be responsible for dilating peripheral arteries and improving walking independence.

"Polyphenol-rich nutrients could represent a new therapeutic strategy to counteract cardiovascular complications," said, Francesco Violi, study senior author and professor of internal medicine at the Sapienza University.

The researchers said the improvements linked to these compounds in dark chocolate need to be confirmed in a larger study involving long-term consumption.

The research was published in Journal of the American Heart Association.

If you are not inclined to save for the future, you may also have a tendency to ignore your health as researchers have found that poor physical health and financial health are driven by the same underlying psychological factors.

The decision to contribute to a retirement plan predicted whether or not an individual will act to correct poor physical health indicators, the findings showed.

Insufficient retirement funds and chronic health problems are at least partially driven by the same time discounting preferences, the researchers showed.

"We find that existing retirement contribution patterns and future health improvements are highly correlated," said Lamar Pierce, associate professor of strategy at Washington University in St. Louis in the US.

The study appeared in the journal Psychological Science.

Malaria may alter the way people smell to make them more alluring to mosquitoes, according to a new finding that can help detect the deadly disease non-invasively through body odour.

An infection with malaria pathogens changes the scent of infected mice, making those infected more attractive to mosquitoes, researchers have found.

Malaria is and remains a formidable disease that is transmitted to humans by the anopheles mosquito. The pathogen is a protozoan of the genus Plasmodium. If left untreated, malaria can be deadly.

In order to complete its life-cycle, the plasmodium parasite must eventually be acquired by another mosquito, which occurs when the insect bites an infected person.

In a new study, researchers from ETH Zurich and Pennsylvania State University show that the plasmodium parasite appears to manipulate its host by changing the characteristics of the infected individual's body odour, which makes the carrier more attractive to hungry mosquitoes.

Mosquitoes were most attracted to infected mice with a high concentration of gametocytes, the plasmodium parasite's reproductive cells, in their blood.

When the mosquito consumes these cells along with the blood, a new development cycle starts in the mosquito's gut.

However, the pathogens do not appear to trigger the expression of unique scent components.

"There appears to be an overall elevation of several compounds that are attractive to mosquitoes," said Consuelo De Moraes, from ETH Zurich.

The researchers believe it is logical that infected people smell more attractive but do not form highly specific body odours, especially given that the malaria pathogen can also have adverse effects on mosquitoes.

"Since mosquitoes probably don't benefit from feeding on infected people, it may make sense for the pathogen to exaggerate existing odour cues that the insects are already using for host location," said study leader Mark Mescher.

What researchers found most surprising is the fact that the malaria infection leaves its mark on body odour for life.

Even when infected mice no longer had symptoms, their body odour showed that they were carriers of the pathogen.

However, not all stages of the disease smelled the same: the scent profile of the acutely ill differs from the profile found in individuals exhibiting later stages of malaria infection.

Although the findings cannot be directly transferred to human malaria, they suggest that similar effects might be involved in the attraction of mosquitoes to infected people.

In addition to aiding efforts to disrupt malaria transmission by mosquitoes, researchers hope that findings may also be used to develop new non-invasive diagnostic procedures that would facilitate effective screening of human populations for malaria infections, particularly in order to identify individuals who don't otherwise have symptoms but remain capable of spreading the disease.

The study was published in the journal PNAS.

A new study reveals that early exposure to stress can change the parts of developing children's brain.

The study, published in the journal Biological Psychiatry, found that chronic, toxic stress like poverty, neglect and physical abuse can have lasting negative impacts in children.

These kinds of stressors, experienced in early life, might change the parts of developing children's brains responsible for learning, memory and the processing of stress and emotion, researchers said.

These changes may be tied to negative impacts on behaviour, health, employment and even the choice of romantic partners later in life, they said.

The study, carried out by the researchers at the University of Wisconsin-Madison, was based on data from 128 children, aged around 12 years, who had experienced physical abuse, neglect or poverty early in life or came from low socio-economic status households.

Researchers conducted extensive interviews with the children and their caregivers, documenting behavioural problems and their cumulative life stress. The team also took brain scans of the children and compared them with brain scans of other children growing up in middle-class families who had not been maltreated.

Researchers found that children exposed to stress had changes in the amygdalas than children who had not.

They also found that children from low socio-economic status households and children who had been physically abused also had smaller hippocampal volumes. Putting the same images through automated software showed no effects.

Behavioural problems and increased cumulative life stress were also linked to smaller hippocampus and amygdala volumes.