The human brain may move through five distinct “network ages,” with some of the most dramatic reorganization happening much earlier in life than many people realize.

In a 2025 Nature Communications study, Alexa Mousley and colleagues analyzed diffusion MRI scans from 4,216 people ranging in age from birth to 90 and used graph-theory tools to model how the brain’s structural connectivity changes as we grow, mature, and age.

By projecting 12 different network metrics into a shared manifold space, they identified four major “topological turning points” at roughly 9, 32, 66, and 83 years of age, which divide the lifespan into five broad epochs of brain network development.

Rather than changing in a smooth, linear way, the brain’s wiring pattern appears to shift direction at each of these ages, with each epoch showing its own characteristic pattern of organization.

In childhood, long-range connections and local clusters are still being built; in adolescence and young adulthood, networks reorganize in a way that supports more efficient information flow; and in later life, different aspects of network topology change again, in patterns that likely relate to both resilience and vulnerability in cognitive aging.

As the authors put it, their findings “underscore the complex, non-linear nature of human development, with unique phases of topological maturation,” which only become visible when looking at brain networks across the entire lifespan, rather than focusing on one age group at a time.

For readers, one key takeaway is that brain health is not a single curve that steadily rises and falls.

Instead, the brain’s structural network passes through several qualitatively different stages, each with its own balance of flexibility and stability.

Although this study was not designed to test specific lifestyle strategies, it reinforces the idea that supporting brain health is a lifelong project—from nurturing development in childhood and adolescence to protecting network integrity in midlife and beyond.

____________________________________________

Adapted from: Mousley, A, Bethlehem, R AI, Yeh, F-C, & Astle, D E. “Topological Turning Points Across the Human Lifespan.” Nature Communications. 2025;16(1):10055. doi:10.1038/ s41467-025-65974-8.