- 10:30
Contrary to popular belief, the human brain doesn’t reach full maturity until around age 32. A British study identifies five major phases in brain development, reshaping our understanding of adolescence and aging. Here’s a closer look at a finding that challenges long-held assumptions.
“Our brain does not age, it evolves,” noted neurologist Yves Agid. But how far does this evolution go? For decades, scientists have tried to map the mysterious changes that shape our minds from early childhood through old age. A British team led by Duncan Astle at the University of Cambridge has now taken a major step forward. By analyzing nearly 4,000 MRI scans, they have identified five distinct phases that structure the brain’s development across a lifetime. Their study, published in late November 2025 in Nature Communications, challenges the long-held notion that the brain is fully mature in adulthood. In fact, our gray matter appears to remain, in a sense, “adolescent” until the age of 32.
The researchers tracked volunteers aged from 0 to 90, aiming to understand how brain connectivity—the way different regions of the brain communicate—changes over time. Using advanced analyses, they identified five major stages, each marked by a “turning point” around the ages of 9, 32, 66, and 83.
— From 9 to 32, the brain is busy optimizing, selecting, and refining its networks. Adolescence, far from ending at the legal age of majority, extends well into the late twenties and early thirties, likely explaining many of the emotional and existential storms experienced during that period. “If you still felt like a teenager at 30, it’s because your brain was still a little one,” Duncan Astle jokes in The Guardian.
— Between 32 and 66, stability takes over. The major reorganizations give way to a plateau where skills and knowledge consolidate, even as the brain retains its capacity for adaptation.
— From 66 onwards, aging begins. White matter, which transmits information across the brain, starts to decline, leaving the brain more vulnerable to certain frailties.
— After 83, connectivity drops further, but the brain leans on key circuits, relying on efficiency and resilience to compensate.
The Critical Ages of Vulnerability
This brain map is more than a scientific curiosity: it helps explain why certain disorders emerge at specific stages of life. Neurodevelopmental disorders appear in childhood, depression often arises during adolescence, and dementia affects the elderly. Each turning point represents a period of heightened vulnerability. Brain plasticity is not constant: it is most pronounced in childhood and adolescence, then gradually declines, though it persists in other forms throughout life.
Duncan Astle emphasizes in The Washington Post: “Understanding these transitions could help target prevention and support at each key stage of life.”
It is important, however, to put this into perspective. These ages are statistical averages. Everyone follows their own pace, shaped by genetics, health, environment, and life experiences. Nothing is predetermined: the brain retains an extraordinary capacity to adapt.
Michael Thomas, a neuroscientist in London, notes to the BBC: “Even an aging brain is never fixed. Intellectual stimulation, physical activity, and social connections remain essential at every age.”
This study paints an optimistic picture: far from experiencing inevitable decline, the brain appears as an organ of constant learning and reinvention. It invites a reconsideration of the boundary between adolescence and adulthood, while highlighting the value of prevention, curiosity, and support at every “season” of life.
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