If you've been told APOE4 means you're destined for Alzheimer's, the science says something very different.

As a vascular surgeon who has spent years treating the end-stages of preventable disease, I want to give you a clearer picture of what APOE4 actually does, and what it doesn't.

In this video, I break down:
- What the APOE4 gene is and how it affects your brain
- Why it raises Alzheimer's risk — but doesn't guarantee it
- The surprising evolutionary reason APOE4 exists in the first place
- What the science actually says about Alzheimer's prevention if you carry the allele
APOE4 is the most significant genetic risk factor for late-onset Alzheimer's. But risk is not destiny. Understanding the biology gives you real options — and that's exactly what this channel is about.

🔔 Subscribe for evidence-based prevention medicine — straight from the OR to your screen.
📩 Questions? Leave them below — I read everything.

I advise you to go through your clinician for testing. But if you want to do it on your own, you can order it here: https://www.ultalabtests.com/partners/lilyjohnstonmd/test/cardio-iq-apoe-genotype-test

Chapters:
0:00 APOE4 is not fate
0:24 What ApoE does in the brain
1:54 ApoE2, ApoE3, and ApoE4 explained
3:22 How APOE4 became linked to Alzheimer’s
4:23 How much APOE4 raises risk
5:37 Why APOE4 does not guarantee Alzheimer’s
6:50 What APOE4 is actually doing
9:46 Amyloid, lipid trafficking, and brain fuel
11:07 Why does APOE4 still exist?
11:29 APOE4 is the original gene
14:51 APOE4 as an immune-modulator gene
17:05 Ancient immune system, modern environment
19:03 The blood-brain barrier feedback loop
20:02 Same gene, different environment
21:36 The gene is fixed, but the provocation isn’t
22:55 What we’ll cover in Part 2
23:40 Should you test for APOE4?
25:04 Knowing turns fate into a head start

This content is for educational purposes only and does not constitute medical advice. Always consult your physician.

Sign up for more information on my own practice here: https://corsighthealth.com/

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

Does lowering LDL cholesterol cause dementia? And how much dementia is actually “vascular” dementia versus Alzheimer’s disease?

In this video, I’m answering two viewer questions about dementia, vascular risk, statins, LDL cholesterol, and brain health. First, we look at the relative prevalence of vascular dementia compared with Alzheimer’s dementia — and why that distinction gets messy fast. Vascular dementia may be less common as a primary diagnosis, but vascular disease often contributes to cognitive decline even when the label is “Alzheimer’s.”

Then we spend most of the video on the bigger fear: whether lipid-lowering therapy — including statins and achieving low LDL-C — increases dementia risk. The short answer: no. Based on the evidence we have, lowering LDL does not appear to cause dementia, and in many patients, reducing cardiovascular and cerebrovascular risk may actually help protect the brain over time.

This is not about pretending statins are perfect or ignoring legitimate questions about brain health. It’s about looking carefully at the evidence instead of letting fear drive the conversation.

If you’re worried about statins, low LDL, Alzheimer’s disease, vascular dementia, or how heart health and brain health overlap, this one is for you.

If you missed the original: https://youtu.be/Rzz2g9gRL_8?si=z5Fcd-e8o2pYT19j

Chapters:
0:00 Viewer questions on dementia and lipid lowering
0:40 Is vascular dementia less common than Alzheimer’s?
2:00 Why dementia diagnoses overlap
3:17 The vascular contribution to cognitive decline
5:22 Why cardiovascular prevention matters for brain health
6:43 Can very low LDL or ApoB cause dementia?
8:16 Lipid-lowering drugs and the blood-brain barrier
10:14 What the overall evidence says
12:02 Randomized trials, meta-analyses, and dementia risk
13:30 Very low LDL in PCSK9 inhibitor trials
16:09 Could statins reduce dementia risk?
18:34 Midlife cholesterol and later dementia
20:00 The PCSK9 genetics question
22:15 Evidence strength: what we know and what we don’t

Are you more worried about heart disease risk, dementia risk, or the tradeoff between the two?

Disclaimer:
This video is for general educational purposes only and is not individual medical advice. Please talk with your own physician before making changes to medications or treatment plans.Sign up for more information on my own practice here: https://corsighthealth.com/

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

You asked 349 questions about my LDL video. I'm answering the ones that matter most — including who paid for the study.

Last week I broke down the LDL cholesterol trial. The comments flooded in — and several of you asked exactly the right questions. In this follow-up, I'm going through the most important ones as a vascular surgeon who's spent years treating the consequences of bad cardiovascular advice.

In this video:
🫘 Kidney function & muscle toxicity — one commenter raised a sharp mechanistic point worth spelling out: statins can cause muscle damage → muscle damage could reduce muscle mass → less muscle mass means less creatinine production → which can look like improved kidney function on labs, even if your kidneys haven't actually improved. We walk through whether this confound holds up in the data.
📊 Number Needed to Treat (NNT) — the stat based on ABSOLUTE risk reduction that keeps drug effects in perspective
🔬 Plaque measurements vs. clinical outcomes — why these are NOT the same thing
💰 Funding sources — who sponsored the trial and how to weigh that when reading the results
✅ A genuine surprise at the end — something the authors did that I didn't expect, and that actually matters for how much we can trust this data

If you're on a statin, managing ldl cholesterol, or trying to understand heart disease risk beyond what your doctor has five minutes to explain — this video is for you.

Watch the original video first: https://www.youtube.com/watch?v=Q2lvd9ND7rA

Sign up for more information on my own practice here: https://corsighthealth.com/

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

A common cholesterol drug might protect your brain from Alzheimer's — but I read the actual study, and there's a red flag nobody is talking about.

Nick Norwitz covered this story. I went further — I pulled the original paper published in Aging Biology and read every line. Here's what I found.Researchers ran a hypothesis-free screen of FDA-approved drugs to find compounds that could disrupt the 14-3-3/hexokinase protein interaction — a mechanism implicated in the protein aggregation that drives Alzheimer's disease and other dementias.

Six drugs emerged from the screen. Ezetimibe was one of them, and it stood out for one reason: it can cross the blood-brain barrier. That's where the excitement starts. But it's also where you need to slow down. Because buried in the study design, I found something that changes everything.

As a vascular surgeon who has spent years watching patients lose their brains — and their lives — to preventable disease, this is the kind of detail I can't ignore. It's exactly why I won't be prescribing this for dementia prevention in my practice.This video is for anyone who heard the ezetimibe-for-dementia claim and wanted the full picture — not the highlight reel.

Sign up for more information on my own practice here: https://corsighthealth.com/

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

Is lower LDL cholesterol actually better for your heart? In this video, I break down the brand-new results from the EZ-Pave study to answer the question that keeps my patients up at night: How low should your cholesterol really go?

As a vascular surgeon, I see the end-stage results of heart disease every day.

We’ve heard the "lower is better" mantra for decades, but new research is finally providing the hard evidence we need to settle the debate.

Study link: https://www.nejm.org/doi/full/10.1056/NEJMoa2600283

We’re looking at how LDL cholesterol levels impact actual cardiovascular events and whether adding medications like ezetimibe truly changes the outcome for your heart health.

If you’ve been skeptical about statins or confused by conflicting health trends, this breakdown of the latest science is for you. My mission is to put myself out of business by giving you the truth about prevention before you ever need to see me in the operating room.

For educational purposes only. Not medical advice. Always consult your healthcare provider before changing any treatment plan.

Sign up for more information on my own practice here: https://corsighthealth.com/

High Quality 3rd-party tested supplements at Fullscript (10% discount): https://us.fullscript.com/welcome/ljohnstonmd/store-start

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

I've seen daily aspirin save lives from heart attack — and cause fatal bleeds. As a vascular surgeon, here's my honest take on heart health.

The answer isn't yes or no — it depends entirely on who you are.

In this video I break down the three groups you need to know:

✅ Who SHOULD take daily aspirin — if you've already had a heart attack, stroke, or stent, aspirin for secondary prevention of heart disease is still one of the most evidence-backed interventions we have.

❌ Who SHOULD NOT — the 2022 USPSTF guidelines quietly changed the recommendations for primary prevention. If you haven't had a cardiovascular event, daily aspirin may be doing more harm than good.

⚠️ The gray zone — two situations where the answer gets complicated: elevated coronary artery calcium (CAC) scores and high Lp(a) (lipoprotein a). Both raise your cardiovascular risk in ways the standard guidelines don't fully account for.

This is the conversation your doctor should be having with you — but often doesn't have time for.

I'm a vascular surgeon teaching the prevention side of medicine — the part most doctors don't have time to cover. Subscribe for more evidence-based answers on heart disease, metabolic health, and longevity.

Sign up for more information on my own practice here: https://corsighthealth.com/

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

We hit all the high points today! Nutrition, exercise, lipids, dental health, hormones, and more. We had amazing participation and it was wonderful to have a chance to interact with everyone in real time. Thanks SO much for taking some of your precious weekend to talk cardiovascular health, heart scans, CAC scores, and all the other nerdy prevention things with me. Hope you enjoyed it! If you want me to do more of these in the future, please say so in the comments!

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

Plaque reversal is one of the most debated topics in preventive cardiology, so in this video I react to Dr. Kevin Ham’s CAST protocol for plaque reversal: Causes, Adding Cures, Strengthening the Body, and Training the Mind and Body.

Overall, I think this is a thoughtful framework and I agree with much of it. But as a vascular surgeon who treats advanced atherosclerosis, I also add some nuance around what “plaque reversal” really means, what may be missing from this conversation, and where I’d want more granularity in a real-world cardiovascular prevention plan.

We talk about the causes of plaque buildup, metabolic health, lifestyle change, cardiovascular risk reduction, and the difference between improving risk factors versus actually changing plaque biology. I also share where I think protocols like this can be helpful—and where they risk oversimplifying atherosclerosis.

If you’re trying to understand plaque reversal, atherosclerosis, heart disease prevention, metabolic health, LDL, ApoB, inflammation, insulin resistance, and cardiovascular risk, this video will help you think more clearly about the problem.

Let me know in the comments: Do you think “plaque reversal” is a useful term, or does it create more confusion than clarity?

#PlaqueReversal #Atherosclerosis #HeartDisease #CardiovascularHealth #MetabolicHealth #Prevention

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___________________________
🧬 About Dr. Lily Johnston

Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.