Previous research has found that the human brain reaches maturity sometime in the 20s, but a new study suggests that it never stops developing.
Neuroscientists at the University of Cambridge have identified “five major epochs,” or stages, of brain structure, according to a press release from the university.
Over the lifespan, the brain “rewires to support different ways of thinking while we grow, mature and ultimately decline,” the researchers noted.
The study, published in the journal Nature Communications and led by Cambridge’s MRC Cognition and Brain Sciences Unit, examined the brains of 3,802 people between birth and 90 years old.
They were compared using a specialized MRI scan that tracks how water molecules move through the brain tissue, the researchers stated.
The study pinpointed the following five broad phases of brain structure, separated into four “turning points” between birth and death.
1. Childhood: Birth to 9 years old
In the childhood era of the brain, rapid growth and “network consolidation” occurs, including the expansion of grey and white matter and the stabilization of the brain surface. Grey matter is responsible for processing information in the brain, while white matter enables communication, according to the researchers.
There is also an overproduction of neuron connectors, or synapses, which are whittled down so only the most active ones survive.
“Across the whole brain, connections rewire in the same pattern from birth until about 9 years old,” the researchers noted.
At 9, the brain experiences a “step-change” in cognitive capacity and an increased risk of mental health disorders.
2. Adolescence: 9 to 32 years old
In the adolescence stage, which lasts on average until the age of 32, the growth of white matter continues, while the brain’s communication networks become more refined and efficient.
There is also an increase in connectivity, which enhances cognitive development and learning, the study found.
These developments peak in the early 30s, which is defined as the “strongest topological turning point” of the entire lifespan.
Around age 32, the “most directional changes in wiring and the largest overall shift in trajectory” occur, lead researcher Dr. Alexa Mousley, a Gates Cambridge Scholar, wrote in a statement.
“While puberty offers a clear start, the end of adolescence is much harder to pin down scientifically,” she said. “Based purely on neural architecture, we found that adolescent-like changes in brain structure end around the early 30s.”
3. Adulthood: 32 to 66 years old
Adulthood is the longest era of brain development, lasting more than three decades. In this stage, the brain architecture stabilizes with no major turning points, corresponding with a “plateau in intelligence and personality,” the researchers echoed from other studies.
Meanwhile, regions of the brain during adulthood become more compartmentalized or “segregated.”
4. Early aging: 66 to 83 years old
Around year 66, there are no major structural shifts, but researchers still pointed to “meaningful changes” in the pattern of brain networks. This re-organization is most likely related to general aging, coinciding with reduced connectivity and the degeneration of white matter.
According to Mousley, people at this age face an increased risk of health conditions that can affect the brain, like hypertension.
5. Late aging: 83 years and older
The final brain structure occurs at around 83 years old. While data is limited for this era, there is a noticeable shift in the decline of brain connectivity and an increased reliance on certain regions, the researchers noted.
‘Important context’
Senior author Duncan Astle, professor of neuroinformatics at Cambridge, commented in a statement that “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 behaviors,” he said.
“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.”
This research is the first to identify major phases of brain wiring across a human lifespan, Mousley commented.
“These eras provide important context for what our brains might be best at, or more vulnerable to, at different stages of our lives,” she said. “It could help us understand why some brains develop differently at key points in life, whether it’s learning difficulties in childhood or dementia in our later years.”
In an interview with Fox News Digital, Dr. Paul Saphier, a neurosurgeon and founder of Coaxial Neurosurgical Specialists in New Jersey, commented that although he agrees with the concept of stages of brain aging, the “segregation they proposed is a little bit broad.”
“I think there are more discreet fundamental aging milestones earlier on,” he said. “From birth to 9 years old, there are substantial changes that occur.”
Saphier, who was not involved in the study, noted that certain factors can influence brain aging, such as stimulating children’s brain development with verbal, written, mathematical and musical skills.
“At the opposite end of the spectrum, continuation with these tasks helps prevent accelerated aging in the later years of life,” he said.
Lifestyle factors like healthy diet, limited alcohol intake and avoidance of illicit drug use and smoking can also help promote long-term brain health, according to the expert.
Saphier added, “We also know from research in the ‘blue zones’ that people who live in socially active communities and avoid isolation also have increased brain health and longevity with lower rates of dementia.”
