Scientists have outlined five distinct eras of human brain development after analysing one of the largest collections of brain scans assembled for this purpose. Nearly 4,000 scans, taken from people less than a year old to the age of 90, allowed researchers to trace how brain wiring shifts across a lifetime. The analysis revealed five major developmental epochs separated by four key turning points that appear at about nine, 32, 66 and 83 years of age.

Prof Duncan Astle of Cambridge University, senior author of the research, said the findings show that the brain does not mature in a smooth line. Instead, it reorganises itself during a handful of decisive transitions. He explained that many people reflect on their lives in phases, and the data suggests that the brain also passes through its own eras. Identifying when these structural shifts occur may help scientists understand when the brain is most sensitive to disruption.

The first developmental era runs from birth to around nine years old. This period marks the rapid shaping of a child’s neural network. Babies are born with an abundance of synapses, and the brain gradually removes the weaker ones while strengthening those that are used. During this time, the efficiency of neural connections actually declines, while grey and white matter expand at a significant rate. Cortical thickness reaches its peak and the folding patterns of the brain settle into place.

The second era, adolescence, extends into the early thirties. White matter continues to grow, and the brain becomes more efficient at sending signals across its networks. This increasing sophistication is associated with improvements in thinking and problem solving. Alexa Mousley, who led the research, said that this period should not be misunderstood as teenagers stretching into their late twenties. Instead, the pattern of change simply continues along the same trajectory for longer than previously assumed. She noted that the findings may also provide useful insights into why many mental health conditions emerge during adolescence.

A major shift occurs at around the age of 32. It is the most notable turning point in the study. Some life experiences, such as parenthood, may contribute to this change, although the research did not test this directly. Mousley said that earlier studies show the brains of women alter after childbirth, so it is reasonable to consider that major milestones might influence the broader pattern of reorganisation.

After this turning point, the brain enters its longest era, the adult phase. The architecture becomes more stable, and earlier changes level out. This period aligns with evidence from other studies suggesting that intelligence and personality also reach long periods of consistency during adulthood. Brain regions become more compartmentalised during this time, and communication between them follows more defined routes.

The final two turning points signal the arrival of early ageing and, later, late ageing. Both stages are characterised by a gradual decline in connectivity. Researchers believe these changes come from the slow deterioration of white matter as the brain ages.

The study and its findings were reported in The Guardian, which highlighted how this work offers a clearer map of the brain’s lifespan and opens new directions for understanding vulnerability, resilience and neurological health.