Scientists have identified five major phases of human brain development, suggesting the brain does not mature in a smooth, gradual way but instead shifts direction at key “turning points” throughout life.
A large study of nearly 4,000 brain scans from people aged under one to 90 found four major transition points at around ages 9, 32, 66 and 83, dividing life into five distinct brain “eras”.
Researchers found:
- Birth to age 9: A childhood phase marked by rapid change, where excess neural connections are pruned and brain structure matures.
- Age 9 to early 30s: An adolescent phase where brain networks become more efficient and refined.
- Early 30s to mid-60s: The longest “adult mode,” beginning around age 32, when brain organisation stabilises.
- Mid-60s onward: An “early ageing” phase, marked by declining connectivity.
- Early 80s onward: A “late ageing” phase with further loss of brain network strength.
Researchers measured brain efficiency, connectivity and structure to map these patterns. The biggest shift happens around the early 30s, when the brain moves into its most stable phase. Scientists believe life events such as parenthood may contribute to changes during this period.
Later turning points appeared linked to age-related decline in white matter and overall brain connectivity.
The researchers say understanding these distinct phases could help identify when the brain is most vulnerable to disruption and provide insight into the development of mental health conditions, which often emerge during adolescence.
