Report: Proceedings of the National Academy of Sciences
Tuesday, November 18, 2014
A viral infection that could make nearly half of us more stupid has been discovered by scientists in the United States.
The mind boggling revelation suggests that millions may be carrying a long-lasting infection that impairs the normal functioning of the brain.
Researchers from Johns Hopkins University in Baltimore and the University of Nebraska found the virus in the throats of 44 percent of volunteers tested in the study.
The volunteers who were carrying the infection performed measurably worse in intelligence tests, even when taking into account such factors as age and education.
The virus, "chlorovirus ATCV-1," was previously only known to appear in green algae in freshwater lakes, and scientists have not established how it came to infect humans.
The virus does not appear to have infected watersports enthusiasts exclusively, probably ruling out a direct link to algae, and it is thought that humans could have long carried the virus, which had not previously registered with doctors.
The study, published in the Proceedings of the National Academy of Sciences, suggests that chlorovirus ATCV-1 changes the genes in the brain.
The scientists found the virus in throat swabs from 40 out of 92 volunteers, and discovered those with the virus performed measurably worse in cognitive testing.
According to study author Professor Robert Yolken of Johns Hopkins, millions of viruses in the human body are being investigated for the first time.
"We’re really just starting to find out what some of these agents that we’re carrying around might actually do," he told the Healthline website.
"It’s the beginning, I think, of another way of looking at infectious agents — not agents that come in and do a lot of damage and then leave, like Ebola virus or influenza virus.
"This is kind of the other end of the spectrum. These are agents that we carry around for a long time and that may have subtle effects on our cognition and behaviour."
The research team went on to confirm their findings with tests in mice. The infected mice exhibited a decrease in cognition, memory and other brain functions.
The virus also broke through the barrier between blood and tissue, altering the activity of genes in the brains of the mice.
The affected genes included those producing dopamine, a hormone which influences memory, emotion, spatial awareness and pleasure.
According to the University of Nebraska’s Professor James Van Etten, a biologist who first identified the virus in algae 30 years ago: "There’s more and more studies showing that microorganisms in your body have a bigger influence than anything anyone would have predicted, and this could be something along those lines.
"The thing that’s different about what we found is that chlorovirus ATCV-1 is something that we wouldn’t have suspected would actually have any effect on humans or animals.
"It points us in a direction of looking to see if we can improve people’s cognition, their behaviour, by changing the composition of their microbiome [the balance of bacteria and viruses in the body]," he said.
