Does IQ Change With Age? The Impact of Aging on IQ

Aging affects our agility, reflexes, and dexterity, causing a decline in our physical condition. But what happens to our cognitive abilities? Does IQ change with age too? Many psychologists have tackled this question, trying to better understand our brains.

That’s why experts on our team examined quite a bit of research and literature to nail down whether IQ can change with age or not and what the mechanics of cognitive aging are.

So, if you’re interested in the fruits of our labor, let’s do a deep dive and explore this topic together!

What Is IQ, and How Is It Measured?

Does IQ change with age?

IQ, short for intelligence quotient, is a score derived from a standardized test that measures a person’s cognitive and reasoning abilities.

This score was first introduced in 1912 by German psychologist William Stern, who thought it might be a useful tool to identify children with learning disabilities who required extra help in school.

To determine intelligence, Stern adjusted the existing IQ formula, bringing it closer to the one we use today.

At present, the most widely accepted theory on intelligence places everyone’s IQ on the scale, starting at 40 and ending at 160 points. As a rule, people’s intelligence is measured within their own age group—for instance, if a 20-year-old has an IQ score of 100, they are average among 20-year-olds. Their intelligence isn’t stacked up against any other age group.

Standard IQ tests measure cognitive abilities, which are called general intelligence in psychology.

General intelligence is further divided into two types:

• Crystalized intelligence. This type encompasses stored, accumulated knowledge that increases with reading and gathering new experiences.
• Fluid intelligence. This component of intelligence is responsible for the ability to learn, process information, and deal with new situations.

To measure general intelligence and its components, psychologists use one of the three standardized tests: the Stanford-Binet, the Wechsler Adult Intelligence Scale (WAIS), or the Wechsler Intelligence Scale for Children (WISC).

Despite their slight differences, all three tests use a single score and timed tasks to test various cognitive abilities.

Does IQ Change With Age?

A person solving a complex rubic cube

Logically speaking, it’s obvious that IQ changes with age, slowly increasing in childhood and decreasing with the decline of cognitive abilities. And while there is research to support this theory, the answer is a little more complex.

First of all, the changes in intelligence are rarely significant—typically, an individual’s IQ will rise or fall only by a few points. And when a change is that small, it can easily be attributed to different testing conditions or varying levels of the test taker’s concentration.

Moreover, even when a change in IQ is significant, it’s difficult to determine whether it’s connected to age alone or to outside factors.

For instance, how can we be sure a 70-year-old’s IQ is lower than a 20-year-old’s due to their age? The difference could be caused by the younger person pursuing their university degree and actively training their brain.

Ultimately, we can say with certainty that IQ typically increases until early adulthood and may experience significant changes in adolescence. Afterward, it remains fairly stable and only exhibits signs of decline in old age. However, it’s not entirely clear if aging is the only factor contributing to the decrease.

How Does IQ Change With Age?

Although psychologists can’t agree on how exactly general intelligence develops over time, they have no such qualms about its components.

For instance, it’s well known that fluid intelligence increases in childhood and adolescence, reaching its peak in young adulthood. Afterward, it slowly starts decreasing, making it harder for older adults to learn and process new information.

On the other hand, crystallized intelligence behaves in a completely opposite way. The more knowledge you accumulate, the more developed it becomes, actually increasing with age.

Since fluid intelligence decreases and crystalized intelligence increases, general intelligence stays at approximately the same level. Still, since fluid intelligence is high during adolescence and young adulthood, psychologists often refer to this period as the peak of intelligence.

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How Aging Affects Other Types of Intelligence

So far, we’ve only discussed the effect of age on general intelligence. However, according to Gardner’s theory, there are nine additional types of intelligence to consider.

These include:

• Visual-spatial intelligence
• Linguistic-verbal intelligence
• Logical-mathematical intelligence
• Intrapersonal intelligence
• Interpersonal intelligence
• Musical intelligence
• Body-kinesthetic intelligence
• Naturalistic intelligence
• Existentialist intelligence

So, how does age affect these nine intelligences? According to a study performed on high school students, younger high schoolers score better in intrapersonal, naturalistic, logical-mathematical, and existentialist intelligence compared to their older peers.

But does that mean these abilities always decline with age? Not necessarily—the results may be affected by the fact that all participants were adolescents.

Older teenagers, closer to adulthood, are starting to experience anxiety related to identity and relationships, which may skew their results. On the other hand, younger adolescents are still not at that stage and are therefore more likely to come across as more flexible, open-minded, and curious.

By that logic, it’s possible that adults score higher in some types; for instance, intrapersonal or existentialist. Still, there is no conclusive research to confirm this theory.

What Factors Impact IQ Other Than Age?

Although your IQ remains relatively consistent throughout your entire life, certain outside factors can impact it.

The most common ones that may lead to either an increase or decrease in IQ include:

• Education. People with good educational backgrounds tend to have higher IQs since their brains have received higher levels of stimulation. Conversely, poor education can negatively impact IQ scores.
• Trauma. Children who grow up in abusive households score lower on IQ tests than those raised in safe environments. Unfortunately, complex PTSD can have severe consequences for brain development.
• Brain injuries. Even a mild brain injury can cause a drop in IQ. Luckily, the score tends to improve once the damage is treated.
• Drugs. Drug consumption at a younger age can lead to lower IQ scores in adulthood. Studies show an average six-point difference between marijuana smokers and those who don’t consume it. Our article on drugs and IQ goes more in-depth on this topic.

How to Increase Your IQ

Are you worried about your IQ’s potential decline over time? Luckily, there are ways to slow it down or even boost your IQ score. Below, you will find some tips on increasing your IQ through helpful activities that exercise your brain.

#1. Learn New Skills

A person playing an instrument

Learning a new skill activates areas of your brain that are otherwise dormant, likely boosting your intelligence and mental agility.

Although there are no specific skills you need to work on to increase your IQ, learning how to play a musical instrument is always an excellent idea. After all, practicing every day positively impacts your working memory and hearing.

#2. Read Frequently

Does IQ change with age?

Nothing is as effective at engaging your brain as reading a stimulating book. Not only do you gain new insights and perspectives, but you also pick up new vocabulary, improving your crystallized intelligence.

And the earlier you start, the better—psychologists report that children who read have higher IQs later in life than their peers who don’t.

#3. Play Chess

Does IQ change with age - Chess

It’s hardly a coincidence that most top chess players have high IQ scores. The game activates both hemispheres of the brain, forcing you to think both logically and creatively. As a result, playing chess can boost your IQ by as much as ten whole points!

#4. Learn a New Language

A person writing sentences in different languages

Did you know that learning a new language is often recommended for the older population to slow down cognitive decline and prevent dementia? Well, similarly, a new language can help you boost your IQ by activating otherwise dormant parts of your brain and improving your thinking and information retention.

Key Takeaways

So, does IQ change with age? As you’ve seen, it can, but the changes in adulthood and even old age aren’t drastic. And if they are, it’s usually because of outside factors, such as brain injuries, diseases, drugs, or trauma.

However, your IQ isn’t entirely set in stone when you reach adulthood. In fact, you can develop it by making healthy lifestyle choices and regularly exercising your brain. Keeping your brain in good shape can offset cognitive decline, too, so it’s good practice even if you don’t care about your IQ score!

For a deeper dive into the accuracy of IQ tests and their implications, be sure to check out our article 'Are IQ Tests Reliable?' to gain more insights.