New Research Shows Adulthood Starts After 32 As Scientists Shed Light On Five Phases Of Human Brain

Last Updated:November 25, 2025, 20:28 IST

New research by scientists at the University Of Cambridge shows that adolescence lasts until a person’s 30s.

New Cambridge research maps how the human brain rewires itself through life, marking clear turning points at ages 9, 32, 66 and 83. (IMAGE: REUTERS FILE)

Scientists from the University of Cambridge said the brain goes through five distinct phases of life and the key turning points appear at ages nine, 32, 66 and 83.

The study was conducted on 4,000 people up to the age of 90. Scientists ran scans to find connections between their brain cells.

They showed that the brain stays in the adolescent phase until a person’s early thirties, until the time people “peak".

They said that the results can help us understand why risk of mental health disorders and dementia varies through life.

What Are The Five Brain Phases?

The research, accessed by broadcaster BBC, showed that the brain is constantly changing in response to new knowledge and experience but outlines that it is “not one smooth pattern from birth to death".

“The brain rewires across the lifespan. It’s always strengthening and weakening connections and it’s not one steady pattern – there are fluctuations and phases of brain rewiring," Dr Alexa Mousley was quoted as saying by the broadcasters.

Researchers said that some people will reach these landmarks earlier or later but pointed out that it was striking how clearly these ages stood out in the data.

A Look Into The Five Phases Of The Brain

The first period is a person’s childhood when the brain rapidly increases in size. It is also trimming the huge number of extra connections it created early in life. This pruning helps the brain organise itself, but it also means the system isn’t very efficient yet. During this stage, the brain behaves a bit like a child wandering around a park, exploring freely and going wherever their curiosity takes them, instead of moving directly from one point to another.

Researchers said the big shift comes around the age of nine, when the brain’s connections suddenly become far more streamlined. “It’s a huge shift," Dr Alexa Mousley told the broadcaster, calling it the most dramatic change between any of the brain’s phases. This is also the stage when the risk of developing mental health disorders is at its highest.

Adolescence, as science now shows, doesn’t stop with the teenage years. Earlier studies pushed it into the twenties, but this new research indicates it continues right up to the early thirties for many people. This nine-to-32 window is also the only period when the brain’s network actually becomes more efficient. According to Dr Mousley, this supports earlier findings that many aspects of brain function peak in the early thirties. What stood out to her, however, was how stable this phase is that the brain essentially remains in the same developmental mode from age nine all the way to 32.

Once the brain crosses the age of 32, it enters its longest and most stable phase, which stretches for nearly three decades. Changes still happen, but they are far slower than the dramatic shifts seen earlier in life. During this time, the gains in efficiency that peak in the early thirties begin to gradually reverse. Dr Alexa Mousley said this phase matches what many of us notice in real life, like for example, a plateau in intelligence, personality and overall mental sharpness that tends to hold steady through midlife.

News world New Research Shows Adulthood Starts After 32 As Scientists Shed Light On Five Phases Of Human Brain

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