Scientists map five distinct stages of brain development from infancy to old age

Researchers have identified five clear phases of human brain architecture, from the first year of life through the late 80s in a new study published in Nature Communications.

The findings pinpoint four major turning points — at ages nine, 32, 66, and 83 — offering a detailed picture of how the brain’s structure evolves across the lifespan, Euronews writes. 

The study is the first to outline major, lifespan-wide stages of brain wiring, and researchers say it could deepen understanding of vulnerabilities linked to childhood learning difficulties and age-related neurological conditions such as dementia.

“Looking back, many of us feel our lives have been characterised by different phases,” said Duncan Astle, the study’s senior author and a professor of neuroinformatics at the University of Cambridge. “It turns out that brains also go through these eras,” he added.

Astle and his team analysed brain scans from roughly 3,800 people between the ages of zero and 90. The scans trace how water molecules move through brain tissue, enabling scientists to chart neural connections and identify major developmental shifts.

The first phase, spanning infancy to about age nine, is marked by rapid growth. During this period, billions of new neural connections form while inactive ones are pruned. Both grey and white matter expand quickly. Grey matter is responsible for processing and interpreting information, while white matter acts as the communication network that transmits signals across the nervous system. This early stage also brings peak cortical thickness and cortical folding — structural features long linked to healthy brain development.

The brain then enters its adolescent phase, characterised by continued white matter growth and increasingly efficient communication between brain regions. Notably, researchers found this adolescent period lasts until age 32 on average. At that point, the brain shifts into what the team describes as the adult era — the “strongest topological turning point” in human development — when neural architecture stabilises.

This stable period lasts roughly three decades. Around age 66, the brain transitions into an “early ageing” stage, marked by a decline in white matter and weakening neural connections.

“This is an age when people face increased risk for a variety of health conditions that can affect the brain, such as hypertension,” said Alexa Mousley, the study’s lead author and a University of Cambridge researcher.

The final stage begins at about age 83, when connectivity continues to diminish and the brain increasingly relies on specific regions. Data for this phase remains limited, but researchers say the trends are clear.

The findings provide a new framework that could help scientists better understand the neural foundations of conditions affecting memory, language, attention, and behaviour.

“It could help us understand why some brains develop differently at key points in life, whether it be learning difficulties in childhood, or dementia in our later years,” Mousley said.

By Sabina Mammadli