Engineering CAR T cells for Alzheimer's plaque removal

Groundbreaking new study, and a bigger picture of brain health for longevity.

What if we could target amyloid-beta plaque for removal by activating the immune response?

Researchers from Washington University in St. Louis tested out this idea in mice that have Alzheimer’s mutations, and they used CAR-T cells to do this in a nifty way. (Study in PNAS, 2026)

CAR-T cells are currently used in immunotherapy for cancer. They are T cells that are collected from the patient’s body and modified in a lab to have what is called a chimeric antigen receptor (CAR) that targets a specific protein. Then they are then multiplied in the lab, and then reintroduced back into the body. For cancer patients, the CAR T cells are engineered to have whatever specific proteins are on that patient’s tumor cells.

For Alzheimer’s, the researchers engineered the CAR-T cells to recognize amyloid-beta plaque by using antibody fragments from current anti-amyloid drugs (Lecanemab and Aducanumab). They showed that these CAR-T cells could effectively clear amyloid from the dura, which is the thick outer membrane of the brain where lymphatic drainage occurs and the immune cells get activated. By clearing the amyloid in this area, they reduced the deposition of amyloid beta plaque, but they didn’t clear out plaques that were already in the brain.

You don’t want a constantly active (or permanent) CAR expression on T cells because it could cause chronic immune activation or autoimmunity. So the researchers did a transient technology with multiple infusions over several weeks in the mice.

This is a long way from being ready for humans, but as a proof-of-concept, it is pretty neat. The CAR-T immunotherapy for cancer has been developed and refined over the past two to three decades. There are clinical trials underway for autoimmune diseases. The infrastructure is in place, and a lot has been learned.

However, taking it to this level for targeting amyloid in the brain will need a lot more research and trials. Plus, CAR-T therapy in cancer is still really expensive, and they need to balance not triggering damage to the brain. The Aducanumab antibodies by themselves have some serious risks, like brain hemorrhaging. No one wants brain hemorrhaging as a side effect.

With those drawbacks, why do I think this is a nifty study?

My excitement here is that I think prompting the immune system to clear out amyloid-beta plaque is a plausible idea. In the long run, CAR-T may end up not being the best option, but I think this is heading along the right path in promoting the right type of T cell response.

Prior studies:
The focus for decades has been on amyloid-beta deposits as initiating the progression of Alzheimer’s disease. But amyloid-beta alone is insufficient to cause Alzheimer’s — there’s been something missing, and it looks like T cell abnormalities may be the key.

Here’s what’s known about T cells and Alzheimer’s:

• A 2023 study in Nature Neuroscience used a 3D human neuroimmune axis model to show that CD8+ T cells selectively infiltrate Alzheimer's cultures and trigger increased microglial activation, neuroinflammation, and neurodegeneration. They also found that T cell infiltration induces interferon-γ and neuroinflammatory pathways in microglial cells.

• A 2024 study showed that exhausted microglia cells may be at the root of APOE4 Alzheimer’s. This study directly links the immune response, or really a perturbed immune response, to the Alzheimer’s pathology.

• In a 2024 study in PNAS, researchers showed that age-related memory CD8 T cells can generate neurodegeneration with the features of Alzheimer’s mice, upstream of amyloid-beta and tau. Essentially, they could use antigen-specific CD8 T cells to induce plaque and tau tangles. Interferon-gamma was also necessary here.

• A 2025 study by Swiss researchers showed that even in very early stages of Alzheimer’s, there is altered T cell reactivity that can be detected in asymptomatic people. This pattern is different than the T cell activity seen in early symptomatic patients.

• All of this makes sense with the many studies on how brain injuries accelerate neurodegenerative disease.

Brain aging and T cells: Zooming out beyond Alzheimer’s
There’s a bigger picture here, as well, when looking at brain aging, biological age, and T cells.

Another new study in Alzheimer's & Dementia (January 2026) also explores T cells in the brain. The researchers calculated biological age and age acceleration from blood DNA methylation data in 704 older adults. They also looked at associations with clinical Alzheimer’s diagnosis and antemortem biomarker levels. What they found was that eight biomarkers were associated with age acceleration (including tau), and notably, that methylation levels in CD4 and CD8 T cells are associated with age acceleration. Methylation is a kind of off switch for genes, with higher methylation levels in T cells reducing function. Interestingly, the associations with brain aging and T cell changes were a stronger indicator for Alzheimer’s among APOE E3 individuals than those with APOE4.

Where does this leave us?
I freely admit that I don’t fully understand all of the ins-and-outs of the changes in T cells in the brain in aging. However, I have enough understanding to be excited that researchers seem to be making great progress over the last couple of years on putting together more of the puzzle pieces for Alzheimer’s.

The bigger picture is that the brain may be the rate-limiting organ for longevity. A new theoretical paper published in January in Cureus makes the argument that the brain is the biological bottleneck for overall healthspan. When brain function starts to deteriorate, everything goes downhill. As the authors put it: “progressive disruption of neural networks governs functional decline across multiple physiological systems, regardless of peripheral biological age.” The authors of the paper call it a "Brain-First Longevity Framework". Essentially, working on your metabolic health or cardiovascular health doesn’t matter much if your brain is declining faster than the rest of the body.

The authors of that paper mention that treating neurological conditions should be a priority — chronic migraines, major depressive disorder, psychosis, TBI, chronic pain, or sleep disorders shouldn’t be ignored since they cause constant stress on neural circuits. Looking for other studies on this, a 2025 study showed that chronic migraines are associated with accelerated brain aging — a 4-year-older brain age than chronological age.

The practical takeaway here is that treating neurological disorders - depression, migraines, concussions, pain - should be prioritized. It’s easy to be passive about treating a migraine that occurs just once a month or so, but the damage could be cumulative in terms of brain longevity.

Autonomic network regulation is also part of the brain’s core functions - heart rate variability, blood pressure stability, and vascular tone. Heart rate variability is something that can be easily measured and tracked with an Apple watch, Oura ring, Whoop strap, and Garmin trackers. I’m not currently using any of these, so I don’t have a lot of practical buying advice. (Drop your favorites in the comments if you use one of these!)

The other takeaway is that depression, stress, and anxiety should be dealt with so that they don’t degrade your neural networks over time. For example, chronic psychological stress compromises the blood-brain barrier, increases neuroinflammation, and accelerates T cell aging.

So I’ll leave you with the hope that researchers are on the right track for solving Alzheimer’s disease, and the practical takeaway that you should prioritize brain health for longevity and healthspan.