Scientists have identified five major phases of brain development, with key turning points at roughly ages 9, 32, 66 and 83, based on brain scans from nearly 4,000 people aged from infancy to 90.
The study found that childhood brain development runs from birth to about age nine, followed by an adolescent phase lasting until the early 30s. True “adult” brain organisation begins around age 32, marking the longest and most stable phase of neural wiring.
Researchers discovered that early life involves intense “network consolidation,” where unused neural connections are trimmed and brain structure rapidly changes. During adolescence and young adulthood, brain networks become more efficient and refined, supporting better cognitive performance.
From the early 30s, brain structure becomes more stable and compartmentalised. Later turning points, at around 66 and 83, mark the beginning of early and late ageing, where neural connectivity gradually declines, likely due to degeneration of white matter.
Scientists say understanding these turning points could help identify when the brain is most vulnerable to disruption and may offer new insights into mental health and ageing.
