Neuroscientists have discovered five major phases of brain structure in the average person's life, divided into four turning points between birth and death when our brains rewire themselves. The topology of the child's brain lasts from birth until the turning point at age nine, when it enters the teenage phase, an era that lasts on average until age 32. In our early thirties, the brain's neural connections enter adult mode; it is the longest era, lasting more than three decades. The third turning point at age 66 marks the beginning of the early phase of aging of brain architecture. Finally, the late-aging brain matures around age 83.
Musli etc.. compared the brains of 3,802 people aged zero to ninety using MRI diffusion scanning datasets, which map neural connections by tracking how water molecules move through brain tissue. Image credit: Musli etc.., two: 10.1038/s41467-025-65974-8.
“We know that brain structure is critical to our development, but we don't have a complete understanding of how it changes throughout our lives and why,” said Dr Alexa Moseley, a researcher at the University of Cambridge.
“This study is the first to identify the major stages of brain function across the human lifespan.”
“These eras provide important context for what our brains may be best at or more vulnerable to at different stages of our lives.”
“This could help us understand why some people's brains develop differently at key points in life, whether it's learning difficulties in childhood or dementia in later life.”
From infancy through childhood, our brains are defined by the consolidation of networks as the abundance of synapses (connectors between neurons) overproduced in the child's brain are reduced and the more active ones survive.
Connections throughout the brain rewire themselves in the same pattern from birth to age nine.
Meanwhile, gray and white matter rapidly increase in volume so that cortical thickness—the distance between the outer gray matter and the inner white matter—reaches a peak and cortical folds—the characteristic ridges on the outer medulla—stabilize.
By the first turning point at nine years of age, the brain experiences a gradual change in cognitive abilities, as well as an increased risk of mental health disorders.
During the second era of brain structure, adolescence, white matter continues to increase in volume, so the organization of the brain's communication networks becomes increasingly sophisticated, as measured by water diffusion in scans.
This era is defined by efficient connections both within specific areas and rapid connections throughout the brain, which is associated with improved cognitive function.
“Neural efficiency, as you can imagine, is tightly coupled in shortcuts, and adolescence is the only era in which this efficiency increases,” Dr. Moseley said.
“These changes peak on average in the early thirties, which is the greatest topological turning point of the entire lifespan.”
“Around age 32, we see the most directional changes in wiring and the largest overall trajectory shift compared to all other turning points.”
“Although puberty provides a clear beginning, the end of adolescence is much more difficult to define scientifically.”
“Based solely on neural architecture, we found that adolescent changes in brain structure end around the early thirties.”
At 32 years old, the longest era begins – adulthood. Brain architecture stabilizes compared to previous stages – without any major turning points for thirty years. This corresponds to a “plateau in intelligence and personality” based on other studies.
The researchers also found that “segregation” is more noticeable in this era as regions gradually begin to become more segregated.
The turning point at age 66 is much milder and not defined by any major structural shifts, although scientists still found significant changes in the structure of brain networks on average around that age.
“The evidence suggests that a gradual reorganization of brain networks culminates in the mid-sixties,” Dr Moseley said.
“This is likely due to aging, with a further decline in connectivity as white matter begins to degrade.”
“This is the age when people face an increased risk of various diseases that can affect the brain, such as hypertension.”
The final turning point occurs around the age of 83, and the era of the last brain structure begins.
Although data for this era are limited, the defining feature is the transition from global to local, as whole-brain connectivity deteriorates further with increasing dependence on specific regions.
“Looking back, many of us feel that our lives consisted of different stages,” said Cambridge University professor Duncan Astle.
“It turns out that the brain also goes through these eras.”
“Many neurodevelopmental, mental health and neurological conditions are related to the way the brain is wired.”
“Indeed, differences in brain wiring predict difficulties with attention, language, memory and a range of different behaviors.”
“Understanding that the brain's structural journey is not a matter of steady progress, but rather one of a few important turning points, will help us determine when and how its wiring is vulnerable to disruption.”
A paper a description of this study was published November 25 in the journal Natural communications.
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A. Moseley etc.. 2025. Topological turning points in human life. Nat Common 16, 10055; two: 10.1038/s41467-025-65974-8
