A new study has mapped out five phases of brain development that play out over the course of our lives—and four ages seen as pivotal turning points in that process, reports the BBC. The ages are 9, 32, 66, and 83. Researchers at the University of Cambridge analyzed brain scans from about 4,000 people ranging from infancy to age 90, revealing that the brain continues to rewire itself throughout life, but not in a smooth, gradual way. Instead, the process is marked by distinct phases, each with its own characteristics and challenges.
The study, published in Nature Communications, defines the stages as:
- Childhood (birth to age 9)
- Adolescence (9 to 32)
- Adulthood (32 to 66)
- Early aging (66 to 83)
- Late aging (83 and up)
"The brain rewires across the lifespan," says lead author Alexa Mousley. "It's always strengthening and weakening connections, and it's not one steady pattern—there are fluctuations and phases." Childhood is marked by rapid growth in brain size, while adolescence brings a push for efficiency—and a higher risk for the onset of mental health disorders. Notably, the adolescent phase lasts until the early 30s, longer than previously thought. "This doesn't mean that the brain of a 17-year-old and a 30-year-old are the same—it's specifically that the types of changes occurring ... are consistent," says Mousley, per Scientific American.
Adulthood brings a long period of stability, but with a slow decline in brain efficiency. Early aging sees the brain's regions working more independently, a shift that coincides with rising risks for conditions like dementia. The final phase, starting at 83, involves even more pronounced changes, though data is thinner due to the difficulty of finding healthy brains in this age group. The study could shed light on why risks for mental health and neurological disorders change over time.
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