Written by Eric Olson
4 min read
Do IQ Scores Change With Age?
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Try for freeWe asked three psychology and cognitive science experts to weigh in on whether IQ scores change as we age. Their answers reveal the fascinating complexity behind intelligence measurement across the lifespan. From neuropsychologists to quantitative psychologists, these specialists provide evidence-based perspectives on IQ stability that challenge common assumptions. What they reveal about age-related cognitive changes might surprise you.
Louis Matzel has answered Unlikely
An expert from Rutgers University in Genetics, Psychology, Neuropsychology
Although IQ can change for an individual, across a population it is well established that IQ is stable across the lifespan. This does NOT mean that our abilities do not change as we age. IQ (as the name indicates) is a QUOTIENT, i.e., your score is calculated relative to persons of your age. If your IQ is high relative to other 20 year-olds, it is very likely to be high relative to your age-matched peers when you are 90 years old. Likewise if your IQ is low. Nevertheless, we are all much less capable at 90 than we were at 20 (cognitive aging is real and it is profound) . But since IQ scores are age-normalized, your IQ score will remain relatively constant. Abilities change, but IQ scores tend to be very stable.
Hynek Cíglerhas answered Extremely Unlikely
An expert from Masaryk University in Psychology, Quantitative Psychology, Psychometrics, Intelligence
However the intelligence ability is changing during the life, the IQ (intelligence quotient) does not. This measure is defined to have mean of 100 in each age group. So the average IQ e.g. in the age 5 is 100, and the same in the age 50.
The intelligence (ability itself) increases till the age 20-50 (based on the intelligence factor), while after that point it decreases. The highest point differs across people and it also depends on the intelligence factor (“type of intelligence”).
Julia Strait has answered Near Certain
An expert from Stepping Stone Therapy in Psychology, Traumatology, Anxiety
Yes, the scores can change in several ways:
- Research has shown that IQ scores are not stable, as previously thought, and one study even showed that teens’ IQ scores can change up to 21 points (more than one standard deviation, or the amount required to jump from “Average,” say, to Intellectually Disabled, or Gifted). (Read a story about this study here: https://www.theguardian.com/science/2011/oct/19/teenagers-iq-scores-adolescence)
- A large body of research shows that different IQ subscales show different patterns of change with age. Verbal or crystallized intelligence increases relatively steadily with age. However, nonverbal or fluid intelligence improves until the mid-20s to 30s and then slowly declines with further aging.
- Only about 50% of IQ is heritable. Thus, environmental influences (shared and especially nonshared) contribute to improvements or declines in IQ across development. These influences change over time and impact IQ scores.
- Certain traumatic brain injuries, including brain damage due to environmental toxins like lead, can lead to quite dramatic drops in IQ in short periods of time.
- There is growing evidence that adverse childhood experiences, most notably child maltreatment (abuse and neglect), can negatively impact overall IQ scores as well as scores on IQ test subscales, such as verbal memory and processing speed.
- IQ scores do not reflect a “true score” but an estimate. All estimates include error, so IQ scores include error, too. Your score may change though your underlying “true” intelligence does not. That’s why most IQ tests provide a range (called a Confidence Interval) in which your “true” IQ likely falls. The score will change slightly each time you are tested. Each IQ test and score, subscale score, etc. fluctuates within a certain range depending on the reliability of the particular test–usually plus or minus the standard deviation of that test.
Verdict: IQ Scores vs. Actual Cognitive Abilities
The experts reveal an important distinction: while IQ scores are designed to remain stable through age-normalization, actual cognitive abilities change throughout life. Your percentile ranking compared to age-matched peers may stay consistent, but your underlying cognitive capacities follow a natural arc of development and decline. Environmental factors—from education to trauma exposure—significantly impact these abilities. Rather than focusing on a single number, consider how developing knowledge, skills, and cognitive resilience can support brain health across your lifespan.
For more research on cognitive aging and intelligence measurement, explore related topics on Consensus.
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