For years, many believed that the prefrontal cortex—the part of our brain in charge of decision-making and impulse control—didn’t fully mature until age 25, marking the point when we became proper adults. But that wasn’t actually true; it was a widely repeated myth, likely originating from an old study that only examined brain scans up to age 25. Still, we latched onto the number 25, probably because it sounded right. After all, weren’t we all a bit clueless at 23?
If you’re curious about when the brain actually reaches a certain level of maturity, a new study—not just an overenthusiastic TikToker—offers a solid answer. Researchers at the University of Cambridge scanned the brains of about 4,000 people from infancy to age 90 and found that the brain remains in its adolescent phase until our early 30s, when we supposedly “peak.” That means we aren’t fully adult until around age 32. Good news for anyone still figuring things out at 28—you’ve got time!
Published in Nature Communications, the study outlines five broad phases of brain development throughout life, marked by four key turning points. The “childhood brain” lasts from birth until around age nine, when it shifts into the “adolescent” phase. This stage continues, on average, until age 32.
Fred Lewsey from the University of Cambridge explains, “Our early thirties mark when the brain’s neural wiring transitions into adult mode. This is the longest phase, spanning over three decades. A third turning point around age 66 signals the start of an ‘early ageing’ phase in brain structure, and the ‘late ageing’ brain emerges around age 83.”
This research is significant. Dr. Alexa Mousley, a Gates Cambridge Scholar who led the study, notes, “This is the first study to identify major phases of brain wiring across the human lifespan. These stages offer important insights into what our brains excel at or are more vulnerable to during different life periods.”
But don’t get too carried away—it’s not like you suddenly become much smarter or more logical at the magical age of 32, as some of us hovering around that age might hope. Instead, the brain’s structure stabilizes around this time and remains relatively unchanged for the next 30 years. Researchers say this aligns with a “plateau in intelligence and personality” observed in other studies. So maybe it’s not such great news after all?
Essentially, you become more set in your ways—which at least partly explains why it’s so hard to change your boomer parents’ minds once they’ve decided something. That’s science for you.
Frequently Asked Questions
Of course Here is a list of FAQs about the science of adulthood designed with clear natural questions and direct answers
Basic Questions Definitions Concepts
1 What is the true age of adulthood according to science
Science suggests there isnt a single true age Adulthood is a gradual process of brain maturation and most neuroscientists agree the brain isnt fully developed until around age 25
2 Why isnt 18 considered the start of adulthood anymore
While 18 is a legal milestone brain scans show that key areas for judgment impulse control and longterm planning are still actively developing well into a persons mid20s
3 What part of the brain develops last
The prefrontal cortex This is your brains CEOits responsible for complex decisionmaking risk assessment planning for the future and controlling impulses
4 Does this mean a 21yearold isnt an adult
It means they are in a transitional stage called emerging adulthood They have adult capabilities in many areas but are still refining the neural pathways for mature judgment and emotional regulation
Deeper Questions How It Works Why It Matters
5 What exactly is happening in the brain until age 25
The brain is undergoing synaptic pruning where unused neural connections are trimmed away to make the remaining networks more efficient Its also strengthening connections with a fatty substance called myelin which speeds up communication between brain regions
6 How does this explain teenage and young adult behavior
Because the emotional center matures earlier than the rational prefrontal cortex young people are more likely to be impulsive emotionally reactive and influenced by peers as their emotional gas pedal is more powerful than their rational brake
7 Are some peoples brains mature earlier than others
Yes Genetics life experiences and environment all influence the pace of brain development Trauma or chronic stress can delay maturation while supportive and stimulating environments can promote healthy development
8 Does brain development stop at 25
No the brain remains plastic throughout life However the major structural reorganization and efficiency upgrades are largely complete by the mid20s
Practical Implications Common Problems