Leqembi Does Much More Than Remove Plaque
When I was diagnosed with Alzheimer's disease, I thought the goal of treatment was simple: remove the amyloid plaque from my brain.
Then I began learning something that completely changed my understanding of Alzheimer's.
Scientists now believe that the large plaques seen on PET scans are not the first or most damaging form of beta-amyloid. The real trouble begins years earlier with tiny, invisible clusters called oligomers.
This discovery explains why Leqembi was designed to do much more than remove plaque. It also targets oligomers and protofibrils, the toxic building blocks that are now believed to cause much of the earliest brain damage.
To understand why this is so important, we first need to understand what oligomers are.
What Are Oligomers?
Every brain naturally produces a small protein fragment called beta-amyloid. Under normal conditions, these fragments are harmless because the brain continuously clears them away. As we age and have other health problems, tiny amounts of these fragments do not get cleared away. Over a decade or more these fragments pile up near the blood brain barrier where brain refuge is cleared and sent into veins to be cleared by our body.
That build up of beta-amyloid molecules begin to fold into the wrong shape. Instead of floating freely, they become sticky and begin attaching to one another.
The process happens in stages.
One beta-amyloid molecule is called a monomer.
Two joined together form a dimer.
Several molecules create an oligomer.
Oligomers grow into protofibrils.
Protofibrils become fibrils.
Fibrils eventually collect into the amyloid plaques found in Alzheimer's disease.
For years, scientists believed plaques and tangles caused most of the damage. Today, research points to the much smaller oligomers as the real "bad actors."
Think of individual beta-amyloid molecules as tiny drops of honey floating through the brain. Alone, each drop is harmless. But when several drift together, they merge into a larger sticky blob called an oligomer. These tiny clumps are small enough to move throughout the brain and attach themselves to synapses, the tiny connections where brain cells communicate and where neural pathways are formed.
Unlike plaques, which remain relatively stationary, oligomers can travel from synapse to synapse, interfering with communication between neurons long before plaques are visible.
My Unexpected Discovery
While researching Leqembi, I stumbled onto another fascinating piece of the Alzheimer's puzzle completely by accident.
I was reading Dan Brown's latest novel, Secret of Secrets. Brown often blends history, science, and symbolism into his stories, and one passage described the brain as having a filtering system that regulates our awareness of the world around us.
That idea intrigued me. As I dug deeper into the neuroscience, I discovered something I had never heard of before, the remarkable partnership between glutamate and GABA.
The more I researched, the more I realized that this system may explain why oligomers are so destructive.
The Brain's Accelerator and Brake
Your brain depends on two chemical messengers that constantly work together.
Glutamate is the brain's accelerator. It excites nerve cells, allowing us to think, learn, remember, and respond quickly.
GABA is the brain's brake and keeps us calm, helps us sleep, and concentrate. It slows brain activity just enough to prevent neurons from becoming overstimulated.
Every thought, memory, movement, and conversation depends on these two chemicals remaining in balance.
Imagine driving a car. Glutamate presses the gas pedal. GABA applies the brakes. Neither one is "good" or "bad." You need both to arrive safely.
How Oligomers Disrupt This Balance
This is where the story became fascinating to me. Researchers have discovered that oligomers attack the very system that keeps the brain in balance. They cause neurons to release too much glutamate.
They interfere with the brain's ability to remove excess glutamate. They weaken GABA's calming influence.
The result is a brain that is constantly pressing the accelerator while the brakes begin to fail.
Over time this excessive activity damages synapses, the tiny communication points between neurons where memories connect via neural pathways. Eventually neurons slow and begin to die.
Scientists now believe this imbalance occurs years before extensive neuron loss or large plaques appear, making it one of the earliest drivers of Alzheimer's disease.
Why Leqembi Matters
This is why Leqembi represents more than a plaque-removing drug.
It was specifically engineered to recognize and remove oligomers and protofibrils, the toxic forms of beta-amyloid believed to disrupt the glutamate-GABA balance and damage synapses.
By removing these toxic proteins, Leqembi may reduce the constant overstimulation of neurons, allowing the brain's natural communication system to function more normally. Researchers are still studying exactly how much this restores glutamate and GABA balance in people, but laboratory studies strongly support this mechanism.
For me, understanding oligomers transformed how I think about Alzheimer's disease. I no longer see plaque as one of the main enemies. I see oligomers as the first domino to fall, the tiny protein clusters that quietly disrupt the brain's communication system years before symptoms become obvious.
That is why I believe removing oligomers may be one of the most important advances scientists made in treating Alzheimer's disease.
Oligomer and Beta-Amyloid Plaque Removal Work Together
None of this means that plaques are unimportant. Removing amyloid plaque remains one of the greatest advances in Alzheimer's treatment. Plaques serve as a reservoir of toxic beta-amyloid, contribute to chronic inflammation, may impair the brain's waste-clearance system, are associated with the spread of tau pathology, are linked to slower clinical decline when removed, and may enhance the effectiveness of future Alzheimer's therapies. In many ways, Leqembi attacks Alzheimer's on two fronts: removing oligomers eliminates the sparks that disrupt synapses and trigger early as well as continuing brain injury, while removing plaques eliminates much of the fuel that sustains the disease process.
References
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Illodo, S. e. (2024, November). Critical aggregation concentration and reversibility of amyloid-β (1–40) oligomers. Retrieved from Science Direct: https://www.sciencedirect.com/science/article/pii/S0003986124003011
Kenjiro Ono, M. T. (2020, January 30). Protofibrils of Amyloid-β are Important Targets of a Disease Modifying Approach to Alzheimer's Disease. Retrieved from National Library of Medicine: https://pubmed.ncbi.nlm.nih.gov/32023927/
Marianne Renner, P. N. (2010, June). National Library of Medicine. Retrieved from Deleterious Effects of Amyloid β Oligomers Acting as an Extracellular Scaffold for mGluR5: https://pmc.ncbi.nlm.nih.gov/articles/PMC3111138/
Petroff, O. (2002). GABA and Glutamate in the Human Brain. Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Glutamate_receptor?utm_source=chatgpt.com
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