Dementia isn’t something that suddenly appears when memory fades.
By that point, the process has been building silently for years—sometimes decades.
The real window for intervention opens much earlier than most people realize, and new research suggests that up to half of dementia cases could be preventable, even in those with high genetic risk.
In a recent video, longevity physician Dr. Anthony Youn shared a compelling case study and outlined four critical brain systems that determine whether someone becomes more resilient or vulnerable to cognitive decline over time.
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When Genetics Aren’t Destiny
Dr. Youn described a patient from his longevity clinic who had watched multiple family members develop early-onset dementia. Understandably concerned, this high-performing individual didn’t want to wait for symptoms to appear before taking action.
Genetic testing revealed the patient carried an APOE genotype associated with a 12-fold increased risk for Alzheimer’s disease. That sounds terrifying, but Dr. Youn emphasized a crucial distinction.
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A result like this does not tell you what will happen. It just tells you where the brain may be more vulnerable and how aggressively we need to approach this.
He explained that APOE helps the brain handle fats, clear waste, and regulate inflammation. Problems in those systems make the brain more susceptible to environmental damage, but susceptibility isn’t the same as inevitability.
A major report published in The Lancet found that up to 45% of dementia cases could be prevented by addressing specific modifiable risk factors. When multiple factors are addressed together, some analyses show risk reduction exceeding 50%.
System One: Your Brain’s Overnight Cleaning Crew
The first critical system involves something called the glymphatic system—essentially a rinse cycle that runs during sleep.
This system clears metabolic waste and proteins like beta-amyloid, which is directly linked to Alzheimer’s disease. When waste doesn’t clear efficiently, it accumulates and creates a vulnerable environment.
Quality matters more than quantity here. Seven hours of fragmented sleep doesn’t equal seven hours of deep, consolidated rest. The deepest stages—called slow-wave sleep—are when glymphatic activity peaks, and these stages are most easily disrupted.
A massive meta-analysis examining 43 cohort studies covering over 277,000 people identified which factors carried the strongest association with dementia risk. Sleep disturbances came out on top, with a 57% higher risk compared to people without sleep problems—higher than physical inactivity or high blood pressure.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Practical Sleep Protection
Dr. Youn recommends several concrete steps:
- Screen for sleep apnea if you snore heavily or stop breathing during sleep—it’s common and treatable
- Maintain consistent sleep and wake times since the glymphatic system runs on circadian rhythm
- Follow the 3-2-1 rule: stop eating 3 hours before bed, no liquids 2 hours before, and no blue light 1 hour before sleep
- Sleep in cool, dark conditions to maximize deep sleep stages
- Limit alcohol, which directly impairs glymphatic clearance and increases nighttime awakenings
For Dr. Youn’s high-risk patient, ruling out sleep apnea was among the first priorities.
System Two: Brain Fertilizer Called BDNF
The second system involves brain-derived neurotrophic factor, or BDNF—a protein that promotes neuron survival, strengthens connections, and drives neurogenesis (creation of new brain cells).
This happens specifically in the hippocampus, one of the brain’s primary memory centers. Unfortunately, it’s also one of the first areas damaged in Alzheimer’s disease.
The encouraging news? The hippocampus is one of very few adult brain regions where new neurons continue growing throughout life. And one of the most potent ways to release BDNF is through aerobic exercise.
A randomized controlled trial demonstrated that just one year of moderate-intensity aerobic exercise increased hippocampal volume by 2%, effectively reversing one to two years of age-related decline.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Exercise delivers multiple benefits beyond BDNF: increased blood flow means more oxygen and nutrients, reduced systemic inflammation, and improved insulin sensitivity in the brain itself.
How Much Movement Is Enough?
Good news—intensity isn’t essential at first. A meta-analysis of 15 prospective studies showed that any physical activity was associated with a 38% lower risk of cognitive decline.
Research published in JAMA Neurology found that peak benefit occurred around 9,800 steps daily (approximately 50% risk reduction), but the minimum effective dose was just 3,800 steps daily, which still lowered risk by about 25%.
You really don’t have to run a marathon or do these intense sprints for an hour. It’s actually just get off the sedentary baseline. That gap between doing nothing and doing something moderate is where you see the most benefit.
System Three: The Vascular Highway
Dr. Youn spends considerable clinic time on the third system: blood vessels connecting heart to brain.
The brain uses about 20% of cardiac output despite representing only 2% of body weight. When vessels degrade from years of elevated blood pressure, chronically high blood sugar, or inflammation, the brain slowly becomes starved of what it needs.
Chronic high blood pressure damages small vessels maintaining white matter—the brain’s internal wiring that allows different regions to communicate. When these vessels break down, white matter lesions accumulate and communication between brain regions slows, eventually manifesting as vascular dementia.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Midlife hypertension (elevated blood pressure in the 40s and 50s) carries greater dementia risk than later-life elevation because damage accumulates over 20 to 40 years before appearing on cognitive tests.
The same applies to blood sugar. Chronically elevated glucose, insulin resistance, prediabetes, and type 2 diabetes damage those same vessels while driving neuroinflammation.
For the high-risk patient, Dr. Youn aggressively targeted vascular markers—not because anything was critically wrong, but because in a brain already genetically sensitive, vascular environment matters exponentially more.
System Four: Building Cognitive Reserve
The fourth system involves cognitive reserve—a structural surplus built through mentally demanding work, learning new skills, and tackling unfamiliar challenges throughout life.
This reserve creates more synaptic connections and alternative pathways, essentially giving the brain backup routes when damage occurs.
Remarkably, some people with fully confirmed Alzheimer’s pathology on brain scans—amyloid plaques, neurofibrillary tangles, the complete picture—remain cognitively intact and function well daily. Their brains built enough reserve to compensate for damage.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Reserve builds through consistently challenging the brain with new skills and domains. Like muscles, brains respond to demand by building new connections.
Racket Sports: A Multisystem Approach
Dr. Youn frequently recommends racket sports like tennis, pickleball, badminton, or table tennis because they combine multiple brain demands simultaneously.
A large prospective Copenhagen study following over 8,500 people for up to 25 years compared life expectancy gains across different sports. Tennis topped the list with almost 10 additional years of life expectancy compared to sedentary individuals, with badminton second at 6.2 years—both ahead of jogging, swimming, and cycling.
Why? Racket sports combine:
- Physical exertion
- Rapid decision-making
- Hand-eye coordination
- Spatial processing
- Social connection
That last element deserves emphasis. Team sports showed independent cognitive benefits even after adjusting for total physical activity volume, suggesting psychosocial contact matters beyond exercise alone.
The same research found that low physical activity was associated with about 60% increased risk of non-Alzheimer’s dementia regardless of APOE genotype. Even in people with high genetic risk, physical activity remained powerfully protective.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Signals Over Susceptibility
Dr. Youn’s core message centers on daily signals rather than genetic fate.
Your brain is receiving signals every single day. Signals from food and from movement, from the environment. Your body’s always listening. And the question is what signals do we want to send it?
Genetics certainly matter and must be accounted for, but they’re not the final decision maker. The trajectory isn’t fixed—it just requires changing the inputs.
By protecting sleep quality, maintaining regular movement, aggressively managing vascular health, and consistently challenging the brain with new skills and social connection, even those at highest genetic risk can dramatically shift their odds.
The opportunity isn’t waiting until memory changes. It’s in the daily signals sent right now.
