How Common is Hyperlexia? A Look at What the Research Says

How common is hyperlexia? Is hyperlexia rare? Well, let's take a closer look at how common hyperlexia is, based on research.

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Your child has hyperlexia.

That's what the diagnosis paper - yes, singular paper - said as the assessment team shoved me out the door.

I zipped home as quick as I could, tricky considering it was rush hour. I was so eager to consume all the information I could about this new-to-me term.

I start typing furiously into Google, h-y-p-e-r-l-e-x-i-a, as soon as I get home.

And that's when I learned how scarce the information on hyperlexia actually was.

I mean, how often do you type something into Google and get basically no information in return?

That was my reality that day.

I am sure the search results are exponentially greater than what it was when I first searched the word in late 2014...

Regardless, the information is scarce because the diagnosis is rare. Hardly anyone has heard of hyperlexia, even the almighty Google, but just how rare is hyperlexia?

Well, it's time to get nerdy and dig into the research so we can answer the question that's on your mind: how common is hyperlexia?

What is Hyperlexia?

Quickly defined, hyperlexia is a syndrome characterized by the following:

• A precocious, self-taught ability to read words well above age level

• A significant difficulty understanding and using verbal language

• Significant difficulties with social interactions

These resources will help you dig deeper into defining hyperlexia and what hyperlexia means, if you need to familiarize yourself with the diagnosis first:

• Free Hyperlexia Handbook

• What is Hyperlexia?

• Signs of Hyperlexia

• Hyperlexia Diagnosis Process

Is Hyperlexia Rare?

The prevalence of hyperlexia in the general population is unknown. There is no information available on this particular topic at the moment, as Ostrolenk et al. (2017) have pointed out.

However, a few studies have tried to pinpoint how common hyperlexia is in pervasive developmental disorders and autism populations.

Estimates based on these populations range from 5-20%.

The problem is, each study used slightly different definitions of hyperlexia, which makes it trickier to give an accurate prevalence rate.

I think it's safe to say that hyperlexia isn't that common.

I mean I've already mentioned that I personally think it's rare, which is why most people have never heard of hyperlexia in the first place...

A Closer Look at How Common Hyperlexia Is

Here is an overview of the different estimates that have been published in research journals:

• Grigorenko et al. (2002) - estimate that the rate of developmental hyperlexia is 5-20%, but they used a really vague definition of hyperlexia

• Burd et al. (1985) - estimate that the co-occurrence of hyperlexia in autistic children is 6.6%

• Jones et al. (2009) via Ostrolenk et al. (2017) - estimate the rate is 14.1%, but use less strict criteria for their definition of hyperlexia

I usually just summarize the stats above and say that anywhere from 5-10% of autistic children are believed to be hyperlexic.

Is Hyperlexia More Common in Boys or in Girls?

Interestingly, there is no evidence of significant gender differences in the prevalence of hyperlexia (Grigorenko et al., 2002).

Sources Referenced in this Article

• Hyperlexia: Systematic review, neurocognitive modelling, and outcome by Ostrolenk et al. (2017)

• A brief updated examination of the enigma of hyperlexia by Mui Hoon Ng (2013)

• A descriptive study of hyperlexia in a clinically referred sample of children with developmental delays by Grigorenko (2002)

• Inquiry into the incidence of hyperlexia in a statewide population of children with pervasive developmental disorder by Burd et al. (1985)

Other Resources You'll Love

Hyperlexia Research

Free Hyperlexia Handbook

What is Hyperlexia?