01/05/2026 - The brain goes through five distinct phases in life, with key turning points at ages nine, 32, 66 and 83, scientists have revealed. Around 4,000 people up to the age of 90 had scans to reveal the connections between their brain cells. Researchers at the University of Cambridge showed that the brain stays in the adolescent phase until our early thirties when we "peak". They say the results could help us understand why the risk of mental health disorders and dementia varies through life.