Scientists Say These 5 Things Prevent Dementia (Do Them Now)

TL;DR

The Lancet Commission found 45% of dementia cases are preventable through five modifiable risk factors including hypertension, hearing loss, isolation, high blood sugar, and high LDL cholesterol.

Key Points

• 1.The Lancet Commission found nearly half of all dementia cases are preventable. 45% of cases worldwide can be prevented through modifiable factors, not genetics — and in 2024 they added two new factors to their list: vision loss and high LDL cholesterol.
• 2.Hypertension is one of the scariest silent risk factors for dementia. The brain uses 20% of blood flow despite being 2% of body weight; sustained high blood pressure damages small vessels feeding the brain, starving neurons over years without obvious symptoms.
• 3.Hearing loss is one of the strongest risk factors on the entire Lancet list. It forces the brain to expend cognitive reserves just to process speech, reduces social engagement, and causes isolation — creating multiple independent pathways to dementia.
• 4.Chronic social isolation physically shrinks the hippocampus. Loneliness raises cortisol, which is toxic to the brain's memory center; isolated people also exercise less, eat worse, and avoid medical care — compounding cognitive decline across every dimension.
• 5.A landmark Finnish trial of 1,200 adults showed a 25% cognitive improvement over the control group in just two years. Executive function improved 83% more and processing speed 150% more; benefits persisted up to 9 years later, even in high-risk APOE4 gene carriers.
• 6.High blood sugar and high LDL cholesterol damage the small vessels supplying the brain. Hemoglobin A1C above 5.7% indicates pre-diabetes-level vascular damage; high LDL (better measured via ApoB and Lp(a)) causes arterial plaque narrowing linked to vascular dementia.
• 7.Physical activity is more powerful for preventing dementia than brain training. The recommended action plan prioritizes knowing your blood pressure, HbA1c, and ApoB numbers first, then adding regular exercise — even a daily walk — as the highest-leverage entry point.