Four pivotal ages in your brain’s development revealed in new scientific study

The brain goes through five different phases in life, with key turning points occurring at age nine, 32, 66 and 83, scientists have found.

Around 4,000 people under the age of 90 were scanned to reveal the connections between their brain cells.

Researchers at the University of Cambridge have shown that the brain remains in the teenage phase until we reach our “peak” age in our thirties.

They say the findings could help us understand why the risk of mental disorders and dementia varies across the lifespan.

The brain is constantly changing in response to new knowledge and experience, but research shows that it is not one smooth pattern from birth to death.

Instead, these are the five phases of the brain:

• Childhood – from birth to nine years.
• Adolescence – from nine to 32 years.
• Adult age – from 32 to 66 years.
• Early aging – from 66 to 83 years.
• Late aging – from 83 years of age and older.

“The brain rewires itself throughout life. It's always strengthening and weakening connections, and there's not one consistent pattern – there are fluctuations and phases of brain rewiring,” lead study author Dr Alexa Moseley told the BBC.

Some people reach these milestones earlier or later than others, but the researchers say it's striking how clearly these ages stand out in the data.

These patterns have only now emerged due to the number of brain scans available in the study. published in the journal Nature Communications.

Childhood – The first period is when the brain rapidly increases in size, but the excess connections between brain cells, called synapses, created early in life, become thinner.

At this stage, the brain becomes less efficient. It's like a child wandering around the park and going wherever he wants, rather than going straight from point A to point B.

Adolescence – The situation changes dramatically from the age of nine, when connections in the brain undergo a period of ruthless efficiency. “It's a huge shift,” Dr. Moseley said, describing the most profound changes between brain phases.

This is also the time when there is the greatest risk of the onset of mental disorders.

It's no surprise that adolescence begins with the onset of puberty, but recent evidence suggests that it ends much later than we thought. It was once thought to only happen in adolescence, but before neuroscience suggested it continued into the 20s and now into the 30s.

This phase is the only period in the brain when the network of neurons becomes more efficient. Dr Mousley said this supported many measures of brain function, suggesting it peaks around age 30, but added it was “very interesting” that the brain remained in the same phase between nine and 32 years.

Adult life – Next comes a period of brain stability as it enters its longest era, lasting three decades.

Changes at this time are slower compared to previous fireworks, but here we see the improvement in brain efficiency being reversed.

Dr. Mousley said this “corresponds to the plateau of intelligence and personality” that many of us have witnessed or experienced.

Early aging – It starts at age 66, but it's not a sharp and sudden decline. Instead, there are shifts in the pattern of connections in the brain.

Instead of coordinating its actions as a single brain, the organ is increasingly divided into regions that interact closely with each other – much like band members starting their own solo projects.

Although the study looked at a healthy brain, this is also the age when dementia and high blood pressure begin to appear, affecting brain health.

Late aging – Then, at 83, we reach the final stage. There is less data than for other groups because it was more difficult to find healthy brains to scan. Changes in the brain are similar to early aging, but are even more pronounced.

Dr Mousley said she was really surprised by how well the different “ages line up with a lot of important milestones”, such as puberty, health problems later in life and even quite big social shifts in the early 30s, such as parenthood.

The study did not look at men and women separately, but will raise questions such as the impact of menopause.

Duncan Astle, professor of neuroinformatics at the University of Cambridge and member of the team responsible for the study, said: “Many neurodevelopmental, mental health and neurological conditions are related to the way the brain is wired. Indeed, differences in brain wiring predict difficulties with attention, language, memory and a range of different behaviors.”

Director of the University of Edinburgh's Brain Research Center Professor Tara Spiers-Jones, who did not work on the research work, said: “This is a really cool study that shows how much our brains change over the course of our lives.”

She said the results fit “well” with our understanding of brain aging, but cautioned that “not everyone will experience these network changes at the same age.”