Scientists have identified five major phases of brain development across the human lifespan, with key “turning points” occurring at roughly ages 9, 32, 66 and 83, according to a large new brain-imaging study.
The research analysed scans from nearly 4,000 people ranging in age from infancy to 90 years old. Instead of finding smooth, continuous change, the scientists discovered that the brain develops in broad epochs, with sharp shifts in its organisation at specific stages of life.
The five brain “eras” were found to be:
- Childhood: birth to around age 9
- Adolescence: roughly ages 9 to 32
- Adulthood: starting around age 32 and lasting into the mid-60s
- Early ageing: beginning around age 66
- Late ageing: starting around age 83
Researchers measured factors such as how efficiently brain regions communicate, how specialised different areas are, and how reliant the brain is on central “hub” regions.
In early life, the brain undergoes intense “network consolidation,” where excess neural connections are gradually pruned and only the most-used pathways are strengthened. During adolescence, communication between brain regions becomes more efficient, supporting improved thinking and cognitive performance.
The most dramatic shift was observed around age 32, when the brain moves into its longest and most stable phase. During this adult era, brain structure becomes more compartmentalised and overall development plateaus. Life events such as parenthood may influence these changes, though this was not directly tested.
After the mid-60s, connectivity begins to decline as part of the natural ageing process, with further changes becoming more pronounced after the early 80s.
Researchers say understanding these brain “eras” could help identify when the brain is most vulnerable to disruption and may improve understanding of mental health conditions that often emerge during adolescence.
