Yes, your IQ can change. While intelligence is relatively stable across adulthood, it is not fixed. Scores can shift meaningfully during certain life stages, and factors like education, nutrition, and brain development all play a role. The degree of change depends on your age, what type of intelligence you’re measuring, and what’s happening in your life.
How Stable IQ Really Is
A large meta-analysis of longitudinal studies found that cognitive ability scores at age 20 correlate about 0.76 to 0.80 with scores taken five years later. That’s high, but far from perfect. General intelligence (g) reaches an asymptotic stability of about 0.84, meaning roughly 16% of the variation between your two scores reflects genuine change rather than measurement noise.
Stability follows a predictable curve. In preschool children, IQ scores are quite unreliable. Through childhood, stability climbs rapidly. By late adolescence, scores become consistently high in their stability, and they stay that way through late adulthood. So the short answer is: the older you are, the less likely your IQ is to shift dramatically, but some movement is always possible.
The Teenage Years Are a Wild Card
Adolescence is the period when IQ changes most. A landmark study published in Nature tracked teenagers over several years and found that individual IQ scores shifted anywhere from 20 points lower to 23 points higher on verbal measures, and up to 18 points in either direction on nonverbal measures. About one in five teenagers showed a shift of at least 15 points, a full standard deviation on the IQ scale. That’s the difference between “average” and “high average” or between “above average” and “gifted.”
These weren’t just testing flukes. Brain scans showed that the changes in verbal IQ corresponded to changes in grey matter density in a brain region involved in speech, while shifts in nonverbal IQ tracked with changes in the cerebellum, an area tied to hand movements and spatial processing. The teenage brain is physically reorganizing, and those structural changes are reflected in measurable cognitive shifts. If you scored 105 at age 12, scoring 90 or 120 at age 16 is within the range of what researchers have observed.
Two Types of Intelligence Age Differently
IQ tests measure a mix of two broad categories. Fluid intelligence is your ability to reason through novel problems, spot patterns, and think on your feet. Crystallized intelligence is the accumulated knowledge and vocabulary you’ve built over a lifetime. These two follow very different paths as you age.
Fluid intelligence peaks in early adulthood and then gradually declines. Crystallized intelligence, by contrast, keeps growing through roughly your late 60s. Around age 50, the gap between the two trajectories is at its widest: your raw problem-solving speed is noticeably slower than it was at 25, but your depth of knowledge and verbal ability is likely at its peak. A composite IQ score blends both, which is why your total score can remain fairly stable even as the underlying components shift in opposite directions.
Education Has a Measurable Effect
One of the most well-documented ways to raise IQ is simply staying in school. A meta-analysis covering over 600,000 participants across 42 datasets found that each additional year of education adds roughly 1 to 5 IQ points, with an overall average of about 3.4 points per year. The size of the effect depends on how the study was designed, but the direction is consistent: more schooling means higher scores.
This doesn’t just mean that smarter people stay in school longer (though that’s also true). Studies using natural experiments, like policy changes that raised the mandatory school-leaving age, found effects of about 2 IQ points per additional year. Research using school-age cutoff dates, which compare children who just barely made the enrollment deadline with those born days later, found effects closer to 5 points per year. Education appears to genuinely sharpen cognitive abilities, not just correlate with them.
Brain Training Has Limited Reach
If you’ve seen ads for brain training apps promising to boost your IQ, the evidence is underwhelming. The most studied approach, called n-back training (a working memory exercise where you track sequences of stimuli), does improve performance on the specific task you practice. But a multi-level meta-analysis found that the transfer to fluid intelligence and other general cognitive skills was very small. You get better at the game. You don’t meaningfully get smarter in ways that show up on an IQ test or in daily life.
Nutrition and Early Life Conditions
Early childhood nutrition has lasting effects on IQ that persist for decades. A 40-year follow-up study found that children who experienced moderate to severe malnutrition during infancy carried IQ deficits of about one standard deviation (15 points) into adulthood, even after their physical growth had fully recovered. That gap remained stable from adolescence through middle age.
Early intervention can partially offset this damage. Programs combining cognitive stimulation with nutritional support raised IQ by about 7 points in previously malnourished children, and a study in Guatemala found that protein supplementation during infancy improved cognitive outcomes that were still detectable at age 40. For adults who grew up well-nourished, however, there’s little evidence that dietary changes produce meaningful IQ shifts. The window for nutrition’s biggest impact is early in life, when the brain is developing most rapidly.
Generational Trends Are Shifting
For most of the 20th century, average IQ scores rose by about 2 to 4 points per decade across developed nations, a phenomenon known as the Flynn effect. Better nutrition, more education, and increasingly complex environments likely drove the gains. But recent data suggests this trend is reversing in some populations.
An analysis of IQ test data from 2005 to 2024 found meaningful declines in general intelligence scores. Interestingly, the pattern isn’t simple: scores on individual subtests actually increased, with the largest gains appearing among lower-scoring individuals. What declined was the correlation between different cognitive abilities. In other words, people’s skills are becoming more uneven rather than uniformly rising or falling. Someone might score higher on vocabulary but lower on pattern recognition than their counterpart from 20 years ago. This “ability differentiation” may explain why some studies report IQ gains while others report losses, depending on what they measure.
How Much of a Score Change Is Real
Every IQ test has a built-in margin of error. The standard error of measurement on widely used tests like the WAIS-IV means your “true” score sits within a range of a few points on either side of whatever number you receive. If you take the same test twice in a short period, a shift of 3 to 5 points could reflect nothing more than how well you slept, your anxiety level, or random variation in which questions appeared.
For a score change to be considered meaningful, it typically needs to exceed about 10 points. Below that threshold, it’s difficult to separate genuine cognitive change from measurement noise. This is worth keeping in mind if you’ve taken an IQ test at two different points in your life and noticed a modest difference. A 5-point swing is statistically unremarkable. A 15-point swing, especially during adolescence, likely reflects something real happening in your brain.