Adolescence Lasts Into Your 30s: New Study Identifies Five Key Brain Phases
A groundbreaking study from the University of Cambridge has revealed that adolescence extends far beyond the teenage years, continuing until around age 32. The research, which analysed brain scans from nearly 4,000 people aged up to 90, outlines five distinct phases of brain development—each marked by significant changes in how brain cells connect and communicate.
Published in Nature Communications, the findings reshape long-held assumptions about the timeline of brain maturation and may help explain why risks for mental health conditions and dementia vary throughout life.
Five Distinct Phases of Brain Development
The study shows that the brain’s wiring does not follow a smooth, linear path. Instead, it transitions through five clear phases, each with its own biological shifts and behavioural implications.
1. Childhood (Birth to Age 9)
During early childhood, the brain expands rapidly while simultaneously pruning excess synapses. Despite the growth, this period is marked by lower efficiency, as neural pathways take a meandering route rather than direct connections.
2. Adolescence (Age 9 to 32)
At age nine, the brain undergoes a sharp transition toward increased efficiency, marking the start of a prolonged adolescent phase. This stage is notable for significant reorganization of neural networks and is the period when mental health disorders most commonly emerge.
The study suggests this phase continues until the early 30s—supporting recent evidence that brain function peaks around this age.
3. Adulthood (Age 32 to 66)
This long stage is characterized by relative stability. While efficiency begins to decline gradually, the brain’s structure supports consistent cognitive performance. Researchers note this aligns with the observed plateau in intelligence and personality traits during adulthood.
4. Early Ageing (Age 66 to 83)
As ageing begins, the brain becomes less unified, with regions functioning more independently. This shift mirrors the age when conditions like high blood pressure and early signs of dementia typically appear, though the study focused on healthy individuals.
5. Late Ageing (83+)
The final phase features more pronounced versions of the changes seen in early ageing. Due to fewer available healthy participants in this age range, data is more limited but still shows notable shifts in brain-network dynamics.
Why These Findings Matter
Lead researcher Dr. Alexa Mousley highlights that these ages emerged clearly from the data, aligning closely with major life milestones such as puberty, family formation, and age-related health changes.
Experts not involved in the study, such as Prof. Tara Spires-Jones from the University of Edinburgh, describe the research as an important contribution to understanding how the brain evolves over a lifetime.
While the study did not separate results by sex, the findings raise relevant future questions, including the impact of menopause on brain-network changes.
What This Means for Mental Health and Ageing
As many neurological and psychiatric conditions are linked to brain wiring, understanding these phases could help predict and intervene in conditions affecting attention, memory, language, and behaviour. This research underscores that the brain remains dynamic well into midlife, and that ageing brings gradual, not sudden, transitions.
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