A new study has identified four pivotal ages—nine, 32, 66, and 83—at which the human brain undergoes significant structural changes, with findings suggesting adolescence may last until age 32. The research was published Tuesday in the journal Nature Communications.
By analyzing nearly 4,000 brain scans from individuals aged up to 90, scientists uncovered five distinct phases of brain development: childhood (birth to 9), adolescence (9 to 32), early adulthood, late adulthood, and old age. These phases are marked by changes in grey and white matter volume, network structure, and cognitive capacity.
The most significant insight from the study is a redefinition of adolescence. Traditionally defined by institutions like the World Health Organization as spanning ages 10 to 19, adolescence is often understood to conclude by the early twenties. However, this new research suggests brain development associated with adolescence—including personality stabilization and matured white matter growth—continues into the early thirties in Western populations.
“Our findings suggest that in Western countries (ie, the United Kingdom and United States of America), adolescent topological development extends to around 32 years old,” the study’s authors wrote. The researchers did not offer an explanation for cultural variation or data from other parts of the world.
At approximately age nine, humans begin adolescence, coinciding with the onset of puberty and the acceleration of brain restructuring. By 32, white matter integrity peaks and brain networks shift in function and organization.
Duncan Astle, professor of neuroinformatics at Cambridge University and one of the study’s co-authors, told The Independent that the research helps us better identify developmental vulnerabilities: “Looking back, many of us feel our lives have been characterised by different phases. It turns out that brains also go through these eras.”
Beyond adolescence, the study found stability in personality and intelligence through adulthood until around age 66, when signs of brain aging and decline—such as reductions in white matter integrity and connectivity—begin to manifest. At age 83, the brain enters a final critical shift, potentially related to cognitive decline linked to aging illnesses.
The research underscores a more nuanced understanding of brain development and calls for a reevaluation of age-based developmental stages.
Source: Al Jazeera, https://www.aljazeera.com/news/2025/11/26/does-adolescence-last-until-32-scientists-unlock-brains-five-eras
