Cognitive Reserve: How to Keep Your Brain Young
Introduction
We look after the body with exercise and food, but we tend to treat the brain as if its decline were inevitable and unrelated to what we do. The evidence says otherwise: much of how the mind ages depends on how it's used.
The key is a useful concept: cognitive reserve.
There's no 90 % of the brain sleeping, waiting to be activated. There's a plastic organ that responds to use.
What cognitive reserve is
It's the brain's capacity to withstand damage and aging without the effects showing. The concept came from a striking observation: people with similar brain deterioration on tests showed very different levels of symptoms. Some kept a sharp mind despite changes that in others would have caused obvious problems.
The explanation is that a more trained brain has more connections and alternative routes, and compensates for damage by using them. It's a highway with many side roads: if one closes, traffic finds another way.
Reserve doesn't prevent aging or disease: it cushions the impact and delays the point at which it becomes visible. That's an important distinction and it's often told badly.
What builds it
Continuous learning. Education and the habit of continuing to learn throughout life is among the factors most associated with greater reserve.
Demanding mental activity. Learning a language, an instrument, a complex skill. With one condition: the stimulus has to be a challenge. What you already master and do automatically stimulates little, and that's the limit of "brain training" apps: they mostly improve the game you train, with little transfer to daily life.
Work and hobbies that require thinking.
Social life. Talking, empathizing and coordinating with others is complex mental exercise. Social isolation appears as a risk factor in the major dementia reports.
Physical exercise. It may be surprising to see it here, and it's among the most protective: it improves cerebral blood flow and is consistently associated with better cognitive function.
The risk factors you can actually change
This is the most actionable part, and it comes from the Lancet Commission on dementia: a substantial proportion of cases is associated with potentially modifiable factors across the life course. Among them:
- Untreated hearing loss in midlife, which carries some of the greatest weight and surprises people most. Using hearing aids when appropriate isn't a comfort issue: hearing loss reduces stimulation and isolates you socially.
- Poorly controlled hypertension and diabetes.
- Smoking, excessive alcohol use and obesity.
- Physical inactivity, social isolation and untreated depression.
- Air pollution and head injuries.
None guarantees anything on its own, and the list has one virtue: almost everything that protects the brain also protects the heart.
How to look after your brain
1. Never stop learning. Regularly take on a challenge that forces effort, not just repetition of what you know. 2. Move. Probably the best thing you can do for your brain long term. 3. Cultivate your relationships. Cognitive protection as well as well-being. 4. Check your hearing and vision. And treat them if needed. 5. Control blood pressure, glucose and cholesterol. Vascular health is brain health. 6. Sleep and manage stress. 7. Get off autopilot. New routes, different activities, conversations that make you think.
The 10 % myth
Worth dismantling because it still circulates: "we only use 10 % of the brain" is false. We use practically all of it, though not all at once. There's no dormant 90 % waiting to be unlocked.
The real news is better: you don't have an unused brain, but you do have a plastic one that reorganizes with use at any age.
Common mistakes
Relying on brain-training apps as the main strategy. They improve the game, little more.
Chasing miracle supplements. None has solid evidence for preventing decline in people without deficiencies.
Believing it's too late. Benefits appear at any age, and several risk factors carry weight precisely in midlife.
Stimulating without challenging. Doing the same easy crossword for years doesn't build reserve.
Ignoring hearing. The most underestimated modifiable factor on the list.
Conclusion
Your brain isn't doomed to switch off with the years: to a large extent it ages according to how you use it and how you look after your vascular and sensory health. Building cognitive reserve looks a lot like living an active, challenging life. If you pick one thing this week, make it the least obvious: if you've been turning up the TV or asking people to repeat themselves, get your hearing checked. It's the intervention with the best effort-to-benefit ratio on this whole list.
References
- Stern, Y. (2012). Cognitive reserve in ageing and Alzheimer's disease. The Lancet Neurology, 11(11).
- Livingston, G., et al. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396.
- Hillman, C. H., Erickson, K. I., & Kramer, A. F. (2008). Be smart, exercise your heart: Exercise effects on brain and cognition. Nature Reviews Neuroscience, 9(1).
- Simons, D. J., et al. (2016). Do "brain-training" programs work? Psychological Science in the Public Interest, 17(3).