Scientists map five different stages of human aging throughout life

Our brains change in stages, from the moment we are born until the very end of our lives. These changes are steady at times, then sudden at others, and they shape how we learn, think, remember, and respond to the world.

A new study maps out this long journey in a fresh way by showing that the brain moves through five major eras, each with its own style of wiring.

The idea that our brains shift gears four separate times between birth and old age gives a new sense of order to something that often feels mysterious.

Scientists behind this work say these shifts may help explain changes in our abilities, our health, and even our vulnerabilities as we grow older.

These insights might someday help people understand why some children struggle in school or why certain adults face memory loss later in life.

Scientists mapped the brain’s stages

Researchers at the University of Cambridge studied MRI diffusion scans from 3,802 people ranging from newborns to adults aged ninety.

These scans tracked the movement of water molecules through brain tissue, which showed how neural networks connect.

After studying all the scans, the team identified four major “turning points” that divide life into five brain wiring eras.

Timing of brain stages

The first brain era runs from birth to about nine years old. The next stretches through adolescence until about age 32.

The third, adulthood, spans more than thirty years. An early aging brain era begins around age 66, followed by a late aging era that takes shape at around age 83.

“We know the brain’s wiring is crucial to our development, but we lack a big picture of how it changes across our lives and why,” said Dr. Alexa Mousley, a Gates Cambridge Scholar who led the research.

“This study is the first to identify major phases of brain wiring across a human lifespan.”

Childhood brain stage

In childhood, the brain is busy with “network consolidation.” Babies start with a huge number of synapses.

Over time, the ones that get used are kept and the others are trimmed away. This process runs in a similar pattern for everyone until around nine years old.

During this time, grey and white matter expand quickly. Cortical thickness increases, and the folds on the brain’s surface settle into place.

By age nine, kids hit a shift in cognitive capacity, and risk for certain mental health conditions grows.

Long adolescent era

The adolescent brain era begins around nine and lasts until about 32. During these years, white matter keeps growing, and brain networks become more organized. Communication across regions becomes faster and more efficient.

Mousley explained that “neural efficiency is as you might imagine, well connected by short paths, and the adolescent era is the only one in which this efficiency is increasing.”

This brain era peaks in the early thirties, and the team described that moment as the “strongest topological turning point” of life.

“Around the age of 32, we see the most directional changes in wiring and largest overall shift in trajectory, compared to all the other turning points,” said Mousley.

“While puberty offers a clear start, the end of adolescence is much harder to pin down scientifically. Based purely on neural architecture, we found that adolescent-like changes in brain structure end around the early thirties.”

Steady years of adulthood

At around age 32, the brain enters its longest era. Patterns settle down. The team says this lines up with a “plateau in intelligence and personality.”

They also found that “segregation” becomes more noticeable, meaning regions slowly get more compartmentalized.

Early aging in the mid-sixties

The next shift is lighter. Around age 66, the brain does not hit a dramatic change, but networks still reorganize in meaningful ways.

“The data suggest that a gradual reorganisation of brain networks culminates in the mid-sixties,” said Mousley.

“This is probably related to aging, with further reduced connectivity as white matter starts to degenerate. This is an age when people face increased risk for a variety of health conditions that can affect the brain, such as hypertension.”

Late stage and final brain aging

The last shift happens around age 83. Here, the brain leans more on local connections as global connectivity declines.

The researchers had fewer scans from people in this age group, but they saw a clear pattern of heavier reliance on specific regions.

“Looking back, many of us feel our lives have been characterised by different phases. It turns out that brains also go through these eras,” said senior author Prof. Duncan Astle, professor of neuroinformatics at Cambridge.

He added that many conditions affecting attention, language, memory, and behavior link to the way the brain is wired.

“Understanding that the brain’s structural journey is not a question of steady progression, but rather one of a few major turning points, will help us identify when and how its wiring is vulnerable to disruption,” he explained.

Learning about the aging brain

This work suggests that our brains have their own timeline that does not always match our expectations.

Childhood ends earlier than we think. Adolescence stretches well into adulthood. And the later stages of life involve more subtle changes than people often assume.

These findings may help scientists understand when the brain is most capable of change and when it may need extra support.

As tools for studying the brain improve, researchers may discover even more about how these stages influence learning, mental health, and aging. For now, this study offers a new way to look at the long story of the human brain.

The full study was published in the journal Nature Communications.

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