Gen Z thinks their brain develops fully at 25. Is that true? We investigate

But is there any truth to this? Does the brain really hit some sudden “fully developed” status at 25? Let’s break it down.

What really happens in the brain by 25?

The idea that our brains are fully developed at 25 is a textbook example of pop science: a tiny grain of truth stretched into a catchy internet factoid.

Dr Manish Chhabria, senior consultant, neurology at Sir H N Reliance Foundation Hospital, Mumbai, explained that brain development happens in stages. “While 90 per cent of a child’s brain growth occurs before age five, the prefrontal cortex—the part responsible for decision-making, impulse control, and long-term planning—keeps maturing into our mid-20s.”

Here’s the twist: brain development doesn’t stop at 25. Some parts of the brain continue evolving well into your 30s—and even beyond.

Dr Leah Somerville, a neuroscientist at Harvard, likens it to a dimmer switch, not an on-off button. Brain refinement is a gradual, lifelong process, not a sudden transformation at a specific age. MRI studies have even found structural changes occurring past 30—so if you were hoping to wake up at 25 feeling like a fully-formed adult, bad news: you’re still a work in progress.

Dr Vikram Pratap Singh, Director and Chief Radiologist at Tirupati Diagnostics, agrees, describing the brain as a lifelong work in progress rather than a machine that reaches “full development” at a specific age. (Source: Freepik)

If your brain doesn’t “finish loading” at 25, what’s actually happening? Dr Vikas Naik, consultant neurosurgeon at Fortis Hospital, Rajajinagar, helped break it down for us:

🧠 Teen years (13-18): Your brain is under construction. The emotional and reward centres (limbic system) are in overdrive, while the prefrontal cortex (logic and planning) is still catching up. This explains impulsive decision-making, risk-taking, and, let’s be honest, some very questionable fashion choices.

🧠 Early 20s (18-25): The prefrontal cortex strengthens, refining long-term thinking and self-regulation. Synaptic pruning is in full swing—essentially, your brain is Marie Kondo-ing itself, keeping useful neural connections and discarding the rest.

🧠 Beyond 25: The brain keeps adapting. Myelination (which speeds up brain signals) continues into your 30s, meaning decision-making and emotional regulation can still improve. Plus, neuroplasticity—the brain’s ability to learn and rewire itself—lasts a lifetime.

Dr Vikram Pratap Singh, director and chief radiologist at Tirupati Diagnostics, agreed, describing the brain as a lifelong work in progress rather than a machine that reaches “full development” at a specific age. “Neuroplasticity—the ability of the brain to adapt and create new interconnections—continues throughout life. You can learn new skills, like playing the guitar or speaking a new language, even in your 40s or 50s,” he said.

Is brain maturity the same for everyone?

Not quite. Brain development varies based on genetics, environmental factors, cultural influences and life experiences, according to leading neurologist Dr Bhupesh Kumar. “Factors like stress, trauma, or early life responsibilities can shape neural pathways in unique ways,” he said.

Pranay Aggarwal, sociologist and director of IAS Gurukul, said that cultural perspectives on adulthood influence how we perceive brain development. “In many societies, adulthood is defined by social roles—marriage, work, and responsibilities—rather than by neurological milestones,” he said. In modern Western societies, extended education and delayed financial independence have shifted the perception of maturity, leading to stricter legal age limits for activities like drinking and driving.

Can people under 25 make rational decisions?

While younger adults may process risks differently due to ongoing brain development, it’s a myth that they can’t make rational choices. “A developing brain is not deficient—it is evolving. Young adults are capable of logical thinking based on their experiences. However, they may prioritise emotional input or short-term rewards more than older adults due to the ongoing refinement of the prefrontal cortex,” said Dr Kumar.

So, if you’re under 25, relax—your brain is fine-tuning itself, but that doesn’t mean you can’t make great decisions.

Are you over 25? Congratulations! Your brain is still growing, learning, and changing.

Just maybe don’t use the “my brain isn’t fully developed yet” excuse next time you make a questionable Amazon purchase at 3 AM.