# Your Brain Shrinks 1% Per Year After 40 — 5 Supplements That Slow It Down

Published March 2026 • 5 min read
Tweet Share

### Key Takeaways

- The brain loses approximately 0.5-1% of its volume per year after age 40, accelerating after 60
- Hippocampal shrinkage correlates directly with memory decline and dementia risk
- Omega-3s, magnesium threonate, lion's mane, creatine, and B vitamins have MRI-confirmed neuroprotective effects
- Starting neuroprotection at 40 is far more effective than waiting until symptoms appear at 65

Your brain hit its maximum size sometime around age 25. Since then, it's been shrinking. Not metaphorically. Physically. The organ inside your skull is getting smaller every year, and after 40, the rate accelerates. By the time most people notice something is wrong — the forgotten names, the lost car keys, the word that's right on the tip of your tongue — they've already lost 10-15% of their brain volume. That's not aging gracefully. That's structural decay.

MRI studies tracking brain volume over time paint a picture that should terrify anyone who plans to use their brain past retirement. The hippocampus — the region responsible for memory formation and spatial navigation — shrinks by 1-2% per year after age 50. The prefrontal cortex, which handles decision-making, planning, and personality, loses volume even faster in some individuals. A landmark study in Neurobiology of Aging followed 2,000 adults for 10 years and found that the rate of brain atrophy was the single strongest predictor of who would develop dementia. Not genetics. Not education. Not lifestyle. The speed at which their brain was shrinking.

The good news — and there actually is good news here — is that brain atrophy isn't fixed. It's modifiable. Five compounds have enough clinical evidence behind them that calling them "promising" would be an understatement. Omega-3 fatty acids (specifically DHA at 1,000mg+) have been shown to slow hippocampal volume loss in multiple MRI studies. Magnesium L-threonate is the only form of magnesium that significantly crosses the blood-brain barrier, and a 2010 MIT study showed it increased synaptic density and improved both short-term and long-term memory in aging subjects. Lion's mane mushroom stimulates nerve growth factor (NGF) production — a 2019 double-blind trial showed measurable cognitive improvement in adults with mild cognitive impairment after just 16 weeks.

Creatine, yes the same creatine that bodybuilders use, turns out to be one of the most underrated brain supplements on the planet. Your brain uses 20% of your body's total energy despite being only 2% of your mass, and creatine is a critical energy buffer for neurons. A University of Sydney study gave 5g of creatine daily to vegetarians and found a 20% improvement in working memory and processing speed. The effect was smaller in meat-eaters (who get some creatine from diet) but still significant. And then there are B vitamins — specifically B6, B12, and folate. The OPTIMA trial at Oxford gave high-dose B vitamins to elderly patients with elevated homocysteine and watched on MRI as their rate of brain atrophy slowed by 30%. In the subgroup with the highest homocysteine levels, it slowed by 53%.

The pattern across all five of these compounds is the same: they work better when you start early. Every study that measured timing found that intervention at the "mild cognitive impairment" stage was dramatically more effective than intervention at the dementia stage. And intervention before any symptoms appeared was the most effective of all. By the time you're forgetting where you parked the car, you've already lost neurons that aren't coming back. The supplements can slow the loss. They can protect what remains. But they can't resurrect dead tissue.

Between ages 40 and 80, the average brain loses about 15% of its total volume and 25% of its white matter. That's not inevitable. That's the default outcome when you do nothing. The people who maintain sharp cognition into their 80s and 90s aren't just lucky. They have measurably larger brain volumes on MRI than their declining peers. Your brain is shrinking right now, today, as you read this. What you do about it in the next five years will determine what kind of mind you have for the next thirty.

### Go Deeper

Ready to learn more? These guides break it all down:

Brain Health & Longevity Brain Supplements Guide Best Longevity Stack Take the Longevity Quiz

### Get Longevity Insights Delivered

Science-backed health tips delivered every week.

Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting any new supplement or making changes to your health regimen.