The five brain phases were split into: childhood brain, adolescent brain, adult brain, early ageing brain and late ageing brain. Photo: 123rf
Scientists have discovered the human brain goes through five different phases of life, with key turning points at four different ages.
These "major turning points" occur around the ages of 9, 32, 66 and 83, a media release from the University of Cambridge said.
The neuroscientists from Cambridge University found the brain structure changes over the course of a human life, as the brain rewires to "support different ways of thinking while we grow, mature, and ultimately decline".
The study that was led by the university's MRC Cognition and Brain Sciences Unit compared brains of more than 3800 people aged between 0 and 90.
According to scientist and research lead Dr Alexa Mousley, it is the first study to "identify major phases of brain wiring across a human lifespan".
It found the brain does not shift into "adult mode", on average, until the age of 32.
The five brain phases were split into: childhood brain, adolescent brain, adult brain, early ageing brain and late ageing brain.
"These eras provide important context for what our brains might be best at, or more vulnerable to, at different stages of our lives," Mousley said.
"It could help us understand why some brains develop differently at key points in life, whether it be learning difficulties in childhood, or dementia in our later years."
Childhood brain
According to the media release, brains are defined by "network consolidation" from infancy through to childhood. Connectors in the brain rewire across the whole brain in the same pattern until roughly 9 years old.
At this point, the first turning point, the brain experiences a "step-change" in cognitive capacity - and an increase in risk of mental health disorders.
Adolescent brain
The second turning point sees the brain's communications networks increasingly refine, the media release said.
This continues until a person is in their 30s, when it peaks.
This is the "strongest topological turning point of the entire life span".
Mousley said: "Around the age of 32, we see the most directional changes in wiring and the largest overall shift in trajectory, compared to all the other turning points.
"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 30s."
Adult brain
According to this study, adulthood begins at 32, until around the age of 66.
Researchers say it is at this time that the brain's architecture stabilises.
Early ageing brain
Mousley said data used for the study suggested a "gradual reorganisation" of the brain's networks occurs in the mid-60s.
"This is probably related to ageing, 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 ageing brain
The final turning point for the brain occurs around the age of 83, the media release said.
Data for this stage was limited but showed the whole brain's connectivity declined further.
Scientist Professor Duncan Astle said: "Many neurodevelopmental, mental health and neurological conditions are linked to the way the brain is wired. Indeed, differences in brain wiring predict difficulties with attention, language, memory, and a whole host of different behaviours.
"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."
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