Scientists may have found a cause of dyslexia
Scientists may have found a cause of dyslexia
In people with the reading disability, the cells were arranged in matching patterns in both eyes, which may be to blame for confusing the brain by producing “mirror” images, the co-authors wrote in the journal Proceedings of the Royal Society B.
In non-dyslexic people, the cells are arranged asymmetrically, allowing signals from the one eye to be overridden by the other to create a single image in the brain.
“Our observations lead us to believe that we indeed found a potential cause of dyslexia,” study co-author Guy Ropars of the University of Rennes, told AFP.
It offers a “relatively simple” method of diagnosis, he added, by simply looking into a subject’s eyes.
Furthermore, “the discovery of a delay (of about 10 thousandths of a second) between the primary image and the mirror image in the opposing hemispheres of the brain, allowed us to develop a method to erase the mirror image that is so confusing for dyslexic people” — using an LED lamp.
Like being left- or right-handed, human beings also have a dominant eye.
As most of us have two eyes, which record slightly different versions of the same image, the brain has to select one of the two, creating a “non-symmetry.”
Many more people are right-eyed than left, and the dominant eye has more neural connections to the brain than the weaker one.
Image signals are captured with rods and cones in the eye — the cones being responsible for color.
The majority of cones, which come in red, green and blue variants, are found in a small spot at the center of the cornea of the eye known as the fovea. But there is a small hole (about 0.1-0.15 millimeters in diameter) with no blue cones.
In the new study, Ropars and colleague Albert le Floch spotted a major difference between the arrangement of cones between the eyes of dyslexic and non-dyslexic people enrolled in an experiment.
In non-dyslexic people, the blue cone-free spot in one eye — the dominant one, was round and in the other eye unevenly shaped.
In dyslexic people, both eyes have the same, round spot, which translates into neither eye being dominant, they found.
“The lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities,” said the study authors.
Dyslexic people make so-called “mirror errors” in reading, for example confusing the letters “b” and “d.”
“For dyslexic students their two eyes are equivalent and their brain has to successively rely on the two slightly different versions of a given visual scene,” the duo added.
The team used an LED lamp, flashing so fast that it is invisible to the naked eye, to “cancel” one of the images in the brains of dyslexic trial participants while reading.
In initial experiments, dyslexic study participants called it the “magic lamp,” said Ropars, but further tests are required to confirm the technique really works.
About 700 million people in the world are known to suffer from dyslexia — about one in ten of the global population.
WHO: Alcohol abuse kills 3 million a year, most of them men
- Of all deaths attributable to alcohol, 28 percent were due to injuries, such as traffic accidents and interpersonal violence
- An estimated 2.3 billion people worldwide drink alcohol, with average daily consumption of people at 33 grams of pure alcohol a day
GENEVA: More than 3 million people died in 2016 due to drinking too much alcohol, meaning one in 20 deaths worldwide was linked to harmful drinking, the World Health Organization (WHO) said on Friday.
More than three quarters of these deaths were among men, the UN health agency said. Despite evidence of the health risks it carries, global consumption of alcohol is predicted to rise in the next 10 years.
“It’s time to step up action to prevent this serious threat to the development of healthy societies,” WHO Director-General Tedros Adhanom Ghebreyesus, said.
In its “Global status report on alcohol and health 2018,” the WHO said that globally, an estimated 237 million men and 46 million women are problem drinkers or alcohol abusers. The highest prevalence is in Europe and the Americas, and alcohol-use disorders are more common in wealthier countries.
Of all deaths attributable to alcohol, 28 percent were due to injuries, such as traffic accidents and interpersonal violence. Another 21 percent were due to digestive disorders, and 19 percent due to cardiovascular diseases such as heart attacks and strokes.
An estimated 2.3 billion people worldwide drink alcohol, with average daily consumption of people at 33 grams of pure alcohol a day. This is roughly equivalent to two 150 ml glasses of wine, a large (750 ml) bottle of beer or two 40 ml shots of spirits.
Europe has the highest per person alcohol consumption in the world, even though it has dropped by around 10 percent since 2010. Current trends point to a global rise in per capita consumption in the next 10 years, the report said, particularly in Southeast Asia, the Western Pacific and the Americas.
“All countries can do much more to reduce the health and social costs of the harmful use of alcohol,” said Vladimir Poznyak, of the WHO’s substance abuse unit. He said proven, cost-effective steps included raising alcohol taxes, restricting advertising and limiting easy access to alcohol.
Worldwide, 45 percent of total alcohol consumed is in the form of spirits. Beer is the second most popular, accounting for 34 percent of consumption, followed by wine at 12 percent.
The report found that almost all countries have alcohol excise taxes, but fewer than half of them use other pricing strategies such as banning below-cost sales or bulk buy discounts.