Older adults who regularly engage in moderate to vigorous physical activity perform better in mental tasks as they are more flexible in terms of brain functions, a new study says.

The findings could soon help doctors determine how physically active you are simply by imaging your brain.

"We looked at 100 adults between the ages of 60 and 80, and we used accelerometres to objectively measure their physical activity over a week," said one of the lead researchers Agnieszka Burzynska, professor at Colorado State University in the US.

The researchers also used functional magnetic resonance imaging (MRI) to observe how blood oxygen levels changed in the brain over time, reflecting each participant's brain activity at rest.

They evaluated the microscopic integrity of each person's white-matter fibers, which carry nerve impulses and interconnect the brain.

"We found that spontaneous brain activity showed more moment-to-moment fluctuations in the more-active adults," Burzynska noted.

"In a previous study, we showed that in some of the same regions of the brain, those people who have higher brain variability also performed better on complex cognitive tasks, especially on intelligence tasks and memory," Burzynska pointed out.

The researchers also found that, on average, older adults who were more active had better white-matter structure than their less-active peers.

The new findings were reported in the journal PLOS ONE.

Manipulating the spine can help people with lower back pain - but it doesn't work for everyone, according to a new study.

Spinal manipulation, or applying force to the joints of the spine, is a technique commonly used by chiropractors and physical therapists, according to the National Center for Complementary and Integrative Health. However, there is conflicting evidence about whether the treatment actually helps people, the researchers wrote in their study.

In the new study, the researchers found that spinal manipulation therapy (SMT) provided relief for some patients with lower back pain, but not for others. [5 Surprising Facts About Pain]

"The big finding is that both sides have been right all along," said Greg Kawchuk, a professor of rehabilitation medicine at the University of Alberta and co-author of the study. It's not a matter of whether the treatment works or doesn't work, but rather, figuring out the best way to care for each patient, he said.

In the study, 32 people with lower back pain received two spinal manipulation treatments over the course of a week. They told researchers how much pain they felt, and the researchers also looked at objective measures of improvement, including measurements of muscle activity, disc hydration and spinal stiffness. A control group of 16 people underwent similar physical examinations, but did not receive treatment. A third group, of 59 people who did not have back pain, was also included, to provide another comparison.

Among the participants who underwent the spinal manipulation treatments, 15 said that they felt better, and the researchers found that their physical measurements all improved as well, Kawchuk told Live Science. For example, their measurements of disc hydration and spinal stiffness were nearing those of the people without any back pain at the end of the study, he said.

The people who said they did not feel any better did not have those physical changes, Kawchuk said.

It's unclear why the treatment worked for some patients but not others, but one idea is that the people who felt that the treatment worked have different spinal characteristics, Kawchuk said. The researchers need to do a much larger study to see whether that may be the case, he added.

The new study "is the beginning of an attempt to understand why some patients respond to SMT and others do not," said Dr. Allyson Shrikhande, a rehabilitation physician at Lenox Hill Hospital in New York City, who was not involved with the study.

Previous studies have looked at how SMT can affect people's pain levels and degree of disability, but they didn't include the physical measurements, Shrikhande told Live Science in an email.

She added that it would have also been beneficial if the researchers had examined how the treatment affected patient's hamstring flexibility, because this can significantly affect people's bodies.

For the people who were not helped by the spinal manipulation treatments, it's not all bad news.

Future research will be aimed at figuring out what does work for these people, such as massage or surgery, Kawchuk said. The ultimate goal is to be able to match patients with the treatments that work best for them, he said.

"Back pain is not one problem - it's a group of problems," so there won't be one treatment that works for everyone, Kawchuk said.

The study was published on Aug. 31 in the journal Spine.

Scientists have discovered that wild blueberry extracts help prevent dental plaque formation and treat severe gum diseases.

The findings could lead to reduced use of antibiotics to treat the serious gum infection disease called periodontitis.

The researchers from Laval University in Quebec City, Canada, said they were developing an oral device that could slowly release the blueberry extract after deep cleaning to help treat periodontitis.

Gum disease is a common condition among adults that occurs when bacteria form biofilms or plaques on teeth, and consequently the gums become inflamed.

Many people have had some degree of gum inflammation, or gingivitis, caused by dental plaque. The gums get red and swollen, and they bleed easily.

If left unchecked, the condition can progress to periodontitis. The plaque hardens into tartar, and the infection can spread below the gum line and destroy the tissue supporting the teeth.

To treat this condition, dentists scrape off the tartar and sometimes have to resort to conventional antibiotics.

But recently researchers have started looking at natural antibacterial compounds to treat gum disease.

Daniel Grenier and colleagues from Laval University wanted to see if blueberry polyphenols, which work against foodborne pathogens, could also help fight Fusobacterium nucleatum, one of the main species of bacteria associated with periodontitis.

In the lab, the researchers tested extracts from the wild blueberry against F. nucleatum.

The polyphenol-rich extracts successfully inhibited the growth of F. nucleatum, as well as its ability to form biofilms.

It also blocked a molecular pathway involved in inflammation, a key part of gum disease.

The findings were reported in the Journal of Agricultural and Food Chemistry.

Even short term exposure to particulate matter and nitric dioxide (NO2) air pollution, that originate predominantly from the combustion of fossil fuels such as emissions from industrial plants or vehicles increases risk of severe heart attacks, research has found.

The study investigated the effect of short term exposure to air pollution on the risk of ST-segment elevation myocardial infarction (STEMI), a deadly type of heart attack caused by a prolonged blockage of blood supply in the heart.

"The association between STEMI and air pollution was observed within one day of exposure," said researcher Jean-Francois Argacha, cardiologist at University Hospital Brussels in Belgium.

"This was despite the fact that concentrations of air pollutants were within the European air quality standard," Argacha noted.

The researchers used a statistical model to evaluate real-time exposure to air pollution in each part of Belgium with adjustments for population density.

The researchers looked at records of hospitalisations for STEMI in Belgium between 2009 and 2013.

They found that 10 micrograms per cubic metre increases in ambient PM2.5 concentrations were associated with a 2.8 percent increase in STEMI while 10 micrograms per cubic metre rises in NO2 were associated with a 5.1 percent increased risk.

These associations were only observed in men.

"It is possible that only men were affected because of the under representation of women in our study population (less than 25 percent)," Argacha said.

The findings were presented at European Society of Cardiology (ESC) Congress 2015 in London this week.