If you scroll through TikTok or Instagram long enough, you’ll inevitably stumble across the line: “Your frontal lobe isn’t fully developed yet.” It’s become neuroscience’s go-to explanation for bad decisions, like ordering an extra drink at the bar or texting an ex you swore not to.
The frontal lobe plays a central role in higher level functions like planning, decision-making and judgment.
It’s easy to find comfort in the idea that there’s a biological excuse for why we sometimes feel unstable, impulsive or like a work in progress. Life in your 20s and early 30s is unpredictable, and the idea that your brain simply isn’t done developing can be oddly reassuring.
But the idea that the brain, particularly the frontal lobe, stops developing at 25 is a pervasive misconception in psychology and neuroscience. Like many myths, the “age 25” idea is rooted in real scientific findings, but it’s an oversimplification of a much longer and more complex process.
In reality, new research suggests this development actually extends into our 30s. This new understanding changes how we view adulthood and suggests that 25 was never meant to be the finish line in the first place.
No one’s 20s and 30s look the same. You might be saving for a mortgage or just struggling to pay rent. You could be swiping dating apps, or trying to understand childcare. No matter your current challenges, our Quarter Life series has articles to share in the group chat, or just to remind you that you’re not alone.
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Where did the ‘age 25’ myth come from?
The magic number stems from brain imaging studies in the late 1990s and early 2000s. In one 1999 tudy, researchers tracked brain changes through repeated scans in children and teens. They analyzed grey matter, which consists of cell bodies and can be thought of as the “thinking” component of the brain.
Researchers found that during the teenage years, grey matter goes through a process called pruning. Early in life, the brain builds an enormous number of neural connections. As we age, it gradually trims back the ones that are used less often, strengthening those that remain.
This early work highlighted that grey matter volume growth and loss is key for brain development.
(AP Photo/Keith Srakocic)
In influential follow-up work led by neuroscientist Nitin Gogtay, participants as young as four had their brains scanned every two years. The researchers found that within the frontal lobe, regions mature from back to front.
More primal regions, like areas responsible for voluntary muscle movement, develop first, while more advanced regions that are important for decision-making, emotional regulation and social behaviour had not fully matured by the final brain scans around age 20.
Since the data stopped at age 20, researchers couldn’t say precisely when development finished. The age of 25 became the best estimation for the assumed endpoint, and eventually became enshrined in the cultural consciousness.
What newer research reveals
Since those early studies, neuroscience has moved on co
