A study led by Cambridge’s MRC Cognition and Brain Sciences Unit have identified five “major epochs” of brain structure over the course of a human life, as our brains rewire to support different ways of thinking while we grow, mature, and ultimately decline. The team compared the brains of 3,802 people between zero and ninety years old using datasets of MRI diffusion scans, which map neural connections by tracking how water molecules move through brain tissue.

The study explores the development of the brain from zero to 90 years old using nine datasets. They quantified how the brain is organised – from efficiency (e.g., well-connected by short paths) to modularity (e.g., separated into well-connected subgroups of regions). The findings show that the pattern of reorganisation across the lifespan is non-linear. By applying dimensionality reduction methods, we identified that these patterns of reorganisation fall into five phases separated by major turning points around nine, 32, 66 and 83 years old.

These phases of structural rewiring have distinct patterns, such as decreasing efficiency from zero to nine years followed by increasing efficiency from 32 to 66 years old. By understanding key turning points, we may be able to better understand what the brain is most vulnerable to at different ages. Past work shows that the pattern of brain organisation is related to neurodevelopment, mental health and neurological conditions. Therefore, understanding the expected phases of brain rewiring may help us better characterise what is considered healthy, typical change versus signs of something related to a condition or disorder.

The full paper can be read here: https://www.nature.com/articles/s41467-025-65974-8

The full Cambridge University press release can be read here: https://www.cam.ac.uk/stories/five-ages-human-brain