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- 🧠 Your brain development doesn't stop at 25.
🧠 Your brain development doesn't stop at 25.
New study tracked 4,200 brain scans from birth to age 90. Here's what they found.
Your brain isn't done at 25.
For years, we've heard that the frontal lobe "fully develops" by age 25. It became a cultural fact. A reassuring excuse. A milestone most people quietly accepted.
The problem is that it was never accurate.
The original studies stopped scanning people around age 20. Scientists estimated development might finish by the mid-20s. That estimate became gospel.
Then, in 2025, University of Cambridge researchers scanned over 4,000 brains, from infancy to age 90, and found something different…
Brain development continues into your early 30s.
Specifically, the study identified critical turning points at ages 9, 32, 66, and 83. The most significant period runs from age 9 to 32, what researchers call the "adolescent" phase of brain wiring.
During this period, the brain is building and optimizing its network connections. The researchers measured this using "small worldness", essentially, how efficiently your brain routes information between different regions.
Higher small worldness means faster processing, better pattern recognition, and more creative connections between ideas.
This construction reaches peak efficiency around age 32.
After that point, the direction reverses. The brain stops prioritizing new connections and begins reinforcing the pathways it uses most. What you've built becomes your default wiring.
Here's what matters
The window isn't closed for most people reading this.
While the brain development study was observational and didn't test interventions, separate research suggests specific behaviors that support brain health and neuroplasticity during this critical period:
High-intensity aerobic exercise - increases white matter integrity and brain-derived neurotrophic factor (BDNF)
Learning new languages - builds structural changes in regions involved in language processing and executive function
Cognitively demanding activities like chess - strengthens neural pathways through deliberate practice and complex problem-solving
Chronic stress, by contrast, hinders brain development.
None of this is about racing against a deadline.
It's about understanding that small, repeated actions during this window may compound differently than they do later. The same habit - running three times per week, studying a new language for 20 minutes daily, could have different structural effects on your brain in your 20s than in your 50s.
That doesn't mean habits don't work later. They do. Neuroplasticity continues throughout life.
But the primary architecture is being built right now.
If you're inside this window, the question isn't "Am I behind?"
The question is: "What am I building?"
Your brain is still under construction. You're choosing which pathways get reinforced.
🛠️ Tools & Resources
The Brain That Changes Itself - The foundational book on neuroplasticity. Explains in plain language how the brain rewires itself at any age. Start here.
Mind Lab Pro - Universal nootropic with 11 research-backed ingredients including citicoline, phosphatidylserine, and Lion's Mane. Designed to support the exact brain processes mentioned in this newsletter - neuroplasticity, memory formation, and mental clarity.
Can you increase your IQ after 25? - Further reading recommendation.
100+ ChatGPT Prompts to Revolutionize Your Day - Discover how you can leverage ChatGPT to boost efficiency, streamline tasks, and stay ahead in your industry. Supercharge your productivity with HubSpot's comprehensive guide.
❤️ Thank you for reading!
Read previous newsletter issues at EnhancingBrain.com
—Ernest
Founder, Enhancing Brain