For decades, a dementia diagnosis felt like an unavoidable twist of fate. The common belief was simple: if you had “bad genes,” bad luck, or developed specific plaques in your brain, there wasn’t much anyone could do about it.

But medicine is evolving, and the new picture of brain health is far more hopeful. Today, researchers are shifting away from seeing dementia as a sudden, unstoppable disease. Instead, they view it as a “slow-cooked” condition—one that builds quietly over decades and is shaped by everyday factors we actually have the power to change. In fact, a recent Lancet Commission finding suggested that close to half of dementia cases worldwide could be prevented or delayed.¹

Newer 2025 data pushes that number even higher, suggesting up to 65% of cases might be preventable.²

Here is a look at how the science has shifted, and what it means for your everyday brain health.

The Old Story

For a long time, the dominant theory surrounding Alzheimer’s disease (the most common form of dementia) was something called the “amyloid cascade hypothesis“.

Here is how that old story went:

• The Culprit: Sticky proteins called amyloid plaques build up in the brain.
• The Effect: These plaques kill neurons, leading directly to memory loss and cognitive decline.
• The Treatment: Billions of dollars were poured into developing drugs designed to clear these plaques away.

A Widened Lens on Brain Health

While this theory isn’t entirely wrong, scientists have realised it is incomplete. For starters, many older adults walk around with substantial plaque buildup in their brains but maintain perfectly sharp, healthy minds.³

Furthermore, while a new generation of plaque-clearing drugs (like Lecanemab and Donanemab) successfully remove these plaques, they only modestly slow down mental decline – and they come with real side effects.⁴

Because of this, researchers have widened their lens. Instead of looking at Alzheimer’s as a single villain, they now view it more like a long traffic jam. Amyloid plaques are just one car in the pile-up. Other contributing factors include:

• Tau tangles (another type of misfolded protein)
• Chronic inflammation
• Leaky blood vessels in the brain
• Struggling mitochondria (the energy powerhouses of our cells)
• Disrupted sleep

Different types of dementia—such as vascular dementia, Lewy body dementia, and frontotemporal dementia – each have their own unique mix of these factors. The key takeaway? No single factor is doing all the damage on its own.

A Life-Course Condition

Because dementia develops over a lifetime rather than overnight, we have an incredible opportunity to intervene early. Brain health is shaped by dozens of everyday factors we can actively influence, including:

• Blood pressure
• Hearing health
• Sleep quality
• Education
• Social connections (loneliness)
• Air quality
• Not smoking
• Managing your weight to avoid obesity
• Treating depression seriously
• Staying active
• Keeping diabetes well controlled
• Drinking alcohol in moderation
• Avoiding head injury
• Keeping cholesterol in the normal range
• Getting your vision checked regularly
• And finally a new addition: get the Shingrix vaccine given recent evidence for a marked reduction in dementia following the vaccine⁵

By taking care of our bodies, staying socially active, and managing chronic conditions today, we are actively protecting our minds for tomorrow.

What is one small change you are focusing on this week to keep your brain healthy and active?

Derived from an article by Forever Young on Substack