What Is Alzheimer's, Really?

By Shannon Kasun, Neuroscience Specialist

My grandmother had Alzheimer’s disease.

As her granddaughter, I would tell you it is the worst disease imaginable. Watching someone you love— once vibrant, brilliant, sparkling— slowly lose their memories, personality, and independence is heartbreaking beyond words.

But as a neuroscientist, I see something else.

I would say it’s a brain adapting to its environment, doing its best with what it's got. I see Alzheimer’s not just as a disease—but as a signal. A warning. A final attempt by the brain to survive.

The Brain’s Balancing Act

Inside every healthy brain is a delicate physiological seesaw—balancing the creation and destruction of synapses, the connections between neurons that enable us to think, remember, feel, be.

In Alzheimer’s, this seesaw tips. Hard. It favors destruction, leading to a myriad of neuron death and, with it, all the heartbreaking symptoms: confusion, memory loss, and personality changes.

But what tips the seesaw? What feather lands so lightly—and yet so devastatingly—that it sends the whole system crashing down?

To answer that, we have to start at the very beginning.

Meet APP

At the center of the Alzheimer’s story is a protein called amyloid precursor protein (APP).

APP is a receptor—a little antenna sticking out of brain cells, constantly scanning the extracellular environment for messages (i.e., molecules). Specifically, APP is a dependence receptor. Essentially, APP is addicted to certain trophic (i.e., nourishing) molecules, like netrin-1 and vitamin D. When it gets the molecules it needs, it behaves nicely. But when it doesn’t—it tells the cell to go rogue, resulting in its death.

As previously mentioned, APP craves trophic factors—supportive, nurturing molecules like netrin-1, BDNF (brain-derived neurotrophic factor), and vitamin D. When these are abundant and bind to APP, APP gets “cut” by cellular scissors (i.e., proteases) at a single site, producing anti-Alzheimer’s proteins that support neuronal health and survival.

But when these trophic factors are missing? 

APP gets cut at three different sites, producing a killer quartet, one of which is the infamous peptide amyloid-beta.

Once released, amyloid-beta latches onto more APP receptors and triggers them to be cleaved at those same three sites. This produces even more amyloid-beta, which binds to more APP... and the cycle intensifies. Over time, these amyloid-beta fragments begin to clump together, forming sticky plaques that interfere with normal cellular function. These plaques ultimately contribute to widespread neuronal death.

The seesaw is no longer balanced. It’s markedly tilted toward destruction. What starts as a subtle shift becomes a haywire chain reaction—a self-amplifying loop of destruction rooted in one key character: APP.

This Doesn’t Make Sense…

Why would the brain be bioengineered to seemingly self-destruct? Aren’t our bodies evolutionarily designed to survive and preserve themselves?

Paradoxically, this is the brain’s way of surviving. When it senses a lack of essential trophic factors and nutrients, it initiates a coordinated synaptic downsizing. The brain begins reallocating energy and resources toward vital survival functions like breathing, heartbeat regulation, and speech. To protect these core processes, it sacrifices what it deems non-essential—memory, learning, and higher cognition.

So… Can We Tip the Balance Back?

Yes. That’s the good news.

Dr. Dale Bredesen and other researchers have identified dozens of factors—at least 36—that influence which path APP takes: the Alzheimer’s-protecting one or the Alzheimer’s-causing one.

These factors include include:

• BDNF (boosted by resistance training, high-intensity interval training, and sauna use)

• Vitamin D (from sunshine, diet, and supplements)

• Homocysteine (lowered by B vitamins)

• Inflammation markers, glucose levels, and more

  
  

When we optimize these factors—through exercise, nourishment, good sleep, and other healthy habits—we begin to pull the brain away from self-destruction, and instead, nurture it back to health.

Alzheimer’s doesn’t have to be a mystery or a monster lurking in our genes. It’s a message. And more importantly—it’s a call to action.

Support your brain. Feed it. Move it. Challenge it. 

The science is clear: what we do every day can either tip the seesaw toward destruction… or toward resilience.

Let’s tip it back.

References 

Bredesen, D. (2017). The End of Alzheimer's: The First Program to Prevent and Reverse Cognitive Decline.