Hey everybody, welcome back to Explain Malcolm 5, a podcast where we pay your questions you always want to ask and talk about them in a way that you need to understand. We are your host, I'm Tim. And I'm Kevin. So Kevin, today we're talking about something a number of people have experienced or may have friends who have experienced, and that is dyslexia.
How does dyslexia work? And are you dyslexic in all languages? Ah, the language question is a fascinating one. Let's get back to that in just a minute.
But first, let me explain that dyslexia is a learning disability that makes it difficult to read and understand things in the same way that others do. These challenges with reading are not a problem with intelligence. It's because people with dyslexia have trouble reading at a good pace and without mistakes. They may also have a hard time with reading comprehension, spelling, and writing.
At its core, it affects the way the brain understands words. And the most common signs of dyslexia are reading and writing problems. It's definitely a pretty common problem. You might also have friends who have it.
So how common is it? There's a whole wide range of estimates here, depending on how you define dyslexia and the exact criteria you use to diagnose it. But the range is something between 5 to 15% of the whole population suffer from it. If you think about it, that would mean about 700 million people worldwide display some dyslexic traits.
That certainly sounds quite prevalent. So how does it work? What makes a person dyslexic then? So some parts of the brain in dyslexic patients are thought to be not as well connected as they are in some normal patients.
And some scientists also point to abnormal development of their visual nerve cells. But to be honest, there's still many open questions that researchers are working on. Researchers have been trying to find the neurobiological basis of dyslexia since it was first identified all the way back in 1881. But it's just not been easy to pinpoint.
In the last two centuries, scientists, you know, they studied the brains of people who were dyslexic, but they had to wait until after those patients had died. And in more recent times, there are neuroimaging techniques like the fMRI and PET scans that have shown a correlation between both functional and structural differences in the brains of children with reading difficulties. So that means that some people with dyslexia show less electrical activation in parts of the left hemisphere of the brain involved with reading. So is it hereditary then?
Is it genetically linked? The U.S. research here shows that a number of genes are involved, are associated with dyslexia. So it can be caused by genetics, but there are also environmental factors.
Do you remember how we did an episode on being left and right-handed? Oh, yes, I remember that. The question was, why isn't the world 50-50 right and left-handed people, right? Yeah, yeah, that was a really popular episode.
Well, so apparently forcing left-handed children to write with their right hands can sometimes actually be harmful to their developing brains and can result in dyslexia, stuttering, and other learning and speech disorders. So it's like this contribution of gene and environment interaction as it affects reading disability has been intensely studied using studies with twins, and it seems both play a part. Interesting. Now, you explained an important distinction at the very beginning, which is that dyslexia doesn't mean that someone is any less intelligent.
And in fact, there are actually many famous people who have dyslexia. Can you tell us about some of those? That's right. It's definitely not related to IQ.
In fact, Albert Einstein and Stephen Hawking both had dyslexia, and there are lots of film stars with dyslexia, too. I think Tom Cruise, Orlando Bloom, Keanu Reeves, Jay Leno, and Wubi Goldberg, to name a few. Wow, that's quite a list. And in business, too, I believe Richard Branson is dyslexic.
Oh, yes, that's right. Billionaire Richard Branson suffered from dyslexia and was a poor academic student who only went to school until he was about 16 years old. I believe he told a story that on his last day there, his headmaster told him he would either end up in prison or become a millionaire. Well, that's quite a fork in the road.
Two options. Now, back to one of the questions from the very beginning. Are you dyslexic in all languages? Ah, so yes, you can be, but with different shades of difficulty.
So, things like speaking Italian, for example, Italian speakers with dyslexia tend to have less severe reading impairment than English or French speakers due to Italian's simpler and more phonetic spelling. There is actually a fancy term to describe this. It's called the orthographic complexity of a language that directly affects how difficult it is to learn to read it. So, which languages are harder for dyslexics and which are easier?
So, English and French have comparatively deep phonemic orthographies within the Latin alphabet writing system, with complex structures employing spelling patterns on several levels. They could be letter sound correspondence, syllables, or morphemes. While other languages like Spanish, Italian, and Finnish primarily employ letter sound correspondence, so-called more shallow orthographies, which makes them easier to learn for people with dyslexia. How about Chinese?
Oh, well, Chinese is hard, period. It's a logographic writing system with extensive use of symbols. So, this poses problems for dyslexic learners. Okay.
Now, finally, some people say fonts make a difference, and with dyslexia, they often reference comic sans. Oh, well, so this area related to fonts is still widely debated, and there isn't definitive research. But one example often given is that comic sans, the font, is helpful for those with dyslexia. The theory here is that the irregular shape of letters in comic sans allows those with dyslexia to be able to read the letters properly.
Very interesting. Did you learn something new? If you did, send us an email. We are at eli5thepodcast at gmail.com.
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