Have you ever been curious if ADHD could have an impact on someone's IQ? Maybe you've wondered if people with ADHD are potentially smarter - or less intelligent - than average. If you're interested in the relationship between ADHD and intelligence, you've come to the right place.
Though they may appear interconnected, it's crucial to recognize that ADHD and intelligence are separate yet intertwined components of human cognition. While ADHD brings its own set of unique challenges and strengths, it doesn't have a direct correlation with intelligence. But it's more complicated than that.
Just like ADHD itself, intelligence has hidden depths that go beyond what meets the eye.
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- For over a century, IQ testing has been considered the gold standard in measuring intelligence. However, IQ assessments only measure a fraction of someone’s full intellectual capability.
- If an ADHDer does well on an IQ test, it may mask how much ADHD affects their lives or even prevent them from getting diagnosed.
- On the other hand, a low IQ score may misrepresent how intelligent someone with ADHD truly is.
- IQ testing doesn't effectively capture the diverse experiences of individuals with ADHD and might inadvertently promote ableist attitudes and beliefs.
Everything you need to know about IQ assessments
What does "IQ" mean?
IQ is the abbreviation for intelligence quotient, a numerical measurement of a human's intelligence. It's calculated using a standardized test that assesses intellectual abilities compared to the appropriate age group.
What does an IQ test measure?
IQ tests only assess specific cognitive skills, such as memory, problem-solving, reasoning, and verbal skills. And, much of the time, ADHD brains inherently struggle with these kinds of cognitive skills.
IQ tests and scores do not measure or reflect all types of intelligence, such as emotional intelligence, creativity, or practical intelligence (e.g., "street smarts").
Thus, an IQ score does not wholly measure a person's intellectual potential or capabilities.
The shameful history of IQ testing
The term "IQ" has long since transformed from just a type of intelligence testing to a determinant for how people view intelligence. From the beginning, though, both IQ testing and IQ as an overall concept were controversial.
In the early decades of the 1900s, IQ tests were used as a tool for the eugenics movement, resulting in discrimination against non-white ethnic groups and what Henry Herbert Goddard referred to as the "feebleminded."1
IQ testing was used throughout most of the second half of the twentieth century (1950 - 1999) to diagnose intellectual disabilities and psychiatric disorders such as schizophrenia.2
The problem with IQ tests
Even if fully measuring a person's intelligence was possible, IQ testing still wouldn't be a foolproof method. Here's why:
IQ tests are essentially graded "on a curve," meaning your score depends on how well everyone else performed while taking the test. Grading on a curve makes IQ scores a moving target, especially given society's continual growth of knowledge over time (a phenomenon known as the Flynn effect).3
IQ scores also don't factor in how the test is administered, which can determine how well someone performs. For example, if someone with ADHD takes an IQ test in a noisy environment, they might become distracted or overstimulated, affecting their focus and, ultimately, their test score.
Why IQ tests aren't accurate for ADHD brains
Executive functioning skills determine IQ scores.
Working memory is a form of executive function, a common struggle area among ADHD kids and adults. Challenges with executive functioning skills are also known as executive dysfunction.
As a result, many people with ADHD are at risk of doing poorly on conventional IQ tests since they frequently involve tasks that directly assess working memory capacity. In fact, ADHDers with severe executive dysfunction have been associated with lower-than-average IQs.4 But, remember - this does not reflect their actual intelligence.
On the flip side, it's also not unheard of for people with ADHD to have a high IQ. One study found that ADHD adults with high IQs have fewer executive functioning deficits than their average-IQ ADHD counterparts.5
High performance can mask ADHD struggles.
IQ as a stand-in for academic performance is controversial when discussing ADHD, as not every ADHDer has a low IQ. Unfortunately, many teachers and parents are unaware of this. As a result, ADHDers who do well in school are liable to fly under the radar and go undiagnosed until adulthood.
Another dangerous misconception about ADHD is that it’s little more than a label for misunderstood geniuses. Like high-achieving children, twice-exceptional (2e) adults with ADHD may never get the support they need because they appear not to need any help. Too often, performance masks inner struggles.
IQ tests paint only part of the picture.
Those with a low IQ score, for reasons unknown, are frequently excluded from studies related to ADHD. As a result, the true impact ADHD symptoms may have on IQ cannot be accurately reflected in modern ADHD research.
Neglecting expertise and autism
IQ testing assumes that someone's entire intellectual ability can be calculated and represented with a number. But what happens is that people with a ton of knowledge on a particular topic often receive lower IQ scores because their area of expertise (aka hyperfixation) isn't covered on the test—thereby potentially excluding, for example, autistic people.
Overlooking creative ideas
Likewise, ADHDers often make frequent spelling or grammatical errors on paper while exhibiting other signs of genius, like a natural ability to make connections between seemingly unrelated things and synthesize them to reveal brilliant ideas.
To sum up, a strong argument can be made that IQ testing, at its best, is problematic and, at its worst, can be unfairly biased against those with disabilities. (see: ableism)
Nevertheless, it's crucial to be aware of the limitations and discriminations of IQ tests because the truth is that the inner workings of the ADHD brain are far more complex—and fascinating—than a two or three-digit number could ever convey.
1 Mastering Modern Psychological Testing | The Problem of Bias in Psychological Assessment (2021)
2 Dialogues in Clinical Neuroscience | The assessment of neuropsychological functioning in schizophrenia (2022)
3 WISC-V: Clinical Use and Interpretation - A volume in Practical Resources for the Mental Health Professional | The Flynn Effect and Its Clinical Implications
4 Psychological Medicine | Are changes in ADHD course reflected in differences in IQ and executive functioning from childhood to young adulthood? (2019)
5 Journal of Attention Disorders | High IQ May "Mask" the Diagnosis of ADHD by Compensating for Deficits in Executive Functions in Treatment-Naïve Adults With ADHD (2016)