Peter Attia MD407 ‒ Preventing cardiovascular and Alzheimer’s disease: lowering LDL early, APOE4, and more
Peter Attia MD
Michael Davidson's Path Into Lipidology 0:00
Michael, a cardiologist and lipidologist who runs the lipid clinic at the University of Chicago, explains that his interest in prevention began as a personal passion. His father died of a heart attack at age 47 when Michael was 16, and Michael's own lipid levels turned out to be abnormal, a pattern that ran in his family. He worked on the original niacin trials in medical school in the late 1970s and early 1980s, later became the first researcher to use fish oil capsules to treat lipid disorders during his fellowship, and then moved into statin trials before opening a prevention-focused clinical research center right after training.
The Case for Primordial Prevention 3:01
Michael lays out the concept of primordial prevention, meaning stopping arterial plaque from ever forming rather than waiting until it exists and trying to reverse it. Genomic data show that people who keep LDL low across their entire lifetime largely avoid heart disease, while the current mainstream approach waits until someone already has significant plaque or has already had a heart attack or stroke before treating aggressively. He describes lowering LDL before a heart attack as highly effective, lowering it after a heart attack as still beneficial, and lowering it once heart failure has developed as offering no benefit at all. He introduces what he calls the 8 gram rule: roughly 8 grams of cumulative cholesterol exposure over a lifetime leads to heart disease, which works out to an LDL of 200 mg/dL sustained for 40 years, 100 mg/dL for 80 years, or 80 mg/dL for 100 years, meaning that keeping LDL below 80 for life should prevent heart disease entirely.
Two Brothers, Two Outcomes 6:00
Peter shares that his father-in-law's father also died at 47, echoing Michael's story, and that Michael's own brother, a family doctor, had bypass surgery at age 44. Michael recounts that after his father died, he and his brother both learned their lipids were equally bad. Michael began taking niacin in medical school and then a statin as soon as one became available, while his brother instead adopted a strict vegetarian diet and delayed statins until much later, eventually needing bypass surgery. Michael treats this as a natural experiment showing that the decade between ages 20 and 40 is when plaque begins forming rapidly, making it the most important window for early treatment.
Treating Causes, Not Just Risk Scores 8:00
Peter brings up an idea from a paper by Allan Sniderman, arguing that instead of debating 5, 10, or 15 year risk, the better frame is treating causal drivers of disease. He compares this to smoking, where cessation is urged regardless of a smoker's calculated cancer risk, since smoking is causally linked to cancer even though not every smoker gets cancer and not every cancer patient smoked. Because LDL is causally related to atherosclerotic cardiovascular disease, supported by both Mendelian randomization studies and clinical trials, Michael argues it should be treated early regardless of a person's short-term risk score, just as hypertension and diabetes are treated before complications like stroke, blindness, or kidney disease appear.
Why LDL Treatment Faces Resistance 11:01
Michael offers his explanation for why lowering LDL remains contentious compared to treating blood pressure. Many people believe LDL can be fully controlled through lifestyle changes alone, such as eating fewer eggs or less meat, but genetic testing in his lipid clinic consistently shows a strong genetic component even in patients already living healthily. He also faults primary prevention guidelines from groups like the American Heart Association for not pushing early intervention hard enough, leaving physicians without strong guidance to act sooner. Peter notes the irony that lifestyle changes have a much bigger proven effect on blood pressure than on LDL, yet resistance to medication is far stronger for cholesterol than for hypertension.
Introducing CETP Inhibitors 14:31
The conversation turns to CETP inhibition, a drug class explored by Michael's colleague John Kastelein in an earlier episode, and to torcetrapib, Pfizer's CETP inhibitor that ended in clinical trials around 2006. Michael explains that CETP, or cholesteryl ester transfer protein, moves cholesterol from HDL into LDL, so blocking it raises HDL and lowers LDL while also improving the liver's clearance of LDL. Animals naturally lacking CETP, such as rats and dogs, have low LDL, high HDL, and resist atherosclerosis, while species with CETP, including monkeys, rabbits, and humans, tend toward higher LDL and lower HDL. He suggests this reflects an evolutionary conservation mechanism for cholesterol, since carnivores with abundant dietary cholesterol did not need it while animals with scarcer nutrient access evolved to hoard cholesterol more efficiently.
The HDL Hypothesis and Torcetrapib's Failure 19:00
Michael describes how the field's excitement around raising HDL, fueled by Framingham Heart Study data and modest benefits seen with niacin and fibrates in trials like the Helsinki Heart Study and VA-HIT, drove the rush into CETP inhibitor development. He notes that every 1 percent rise in HDL was linked to roughly a 3 percent drop in risk in these trials, making the potential benefit of a drug that could raise HDL by 50 to 75 percent seem enormous. Torcetrapib was pushed into large trials despite early signs it raised blood pressure by three to five points, and it was ultimately halted due to increased cardiovascular and non-cardiovascular mortality, caused by an off-target effect that markedly increased aldosterone and steroid production from the adrenal glands rather than by the CETP mechanism itself. Michael also walks through how HDL was believed to work mechanistically, picking up cholesterol and inflammatory debris from tissues, including artery walls, and ferrying it back to the liver for clearance and bile production, a process called reverse cholesterol transport, even though the actual amount of cholesterol removed directly from arterial plaque turned out to be minuscule.
Torcetrapib and Dalcetrapib failures 28:00
The conversation reviews earlier CETP inhibitors that tried to fight heart disease by raising HDL cholesterol. Torcetrapib raised HDL by about 75 percent but lowered LDL only slightly, around 10 to 15 percent, and it turned out to have devastating off-target side effects. Dalcetrapib, a weaker CETP modulator described as very safe, raised HDL by 30 to 40 percent with no LDL effect and reduced diabetes risk, but produced no benefit on major adverse cardiac events, meaning no reduction in heart attack or stroke. Both were high-profile failures.
Lily's evacetrapib and early stopping 32:30
Eli Lilly's drug evacetrapib lowered LDL by 15 to 20 percent and raised HDL by about 75 percent, and it was tested in a high-risk secondary prevention population with acute coronary syndrome. The trial was stopped after only two years for futility, but the speaker argues two years was too short, since a similar ezetimibe trial only showed separation in outcomes after that point, and PCSK9 drugs like Repatha and Praluent needed about two years even with larger LDL reductions. Corporate financial pressure at Lily also contributed to the early stop. The drug did show a significant overall mortality benefit and a diabetes benefit, even though it missed its primary cardiac endpoint.
Merck's anacetrapib proves the concept 35:31
Merck's large outcome study, involving roughly 30,000 patients followed for four years, became the trial that saved the CETP class. Starting from a baseline LDL of 60, the drug achieved a 17 percent LDL reduction, about 11 milligrams per deciliter, and produced a 9 percent relative risk reduction in cardiovascular events, matching predictions. Despite this success, the drug never reached market because it accumulated in fat tissue for years and raised environmental concerns, including getting into the water supply, which made it commercially unviable even though it was safe and effective.
Why LDL lowering predicts benefit 37:32
Plotting LDL cholesterol against event rates across primary prevention trials, secondary prevention trials, Mendelian randomization studies, and epidemiology all produce consistent downward lines, reinforcing that LDL lowering causes reduced cardiovascular risk regardless of the method used to lower it. The established formula is that lowering LDL by one millimole, or 38.8 milligrams per deciliter, cuts major cardiovascular risk by about 22 percent, and this relationship is linear based on absolute reduction rather than percentage. Benefits also take time to appear, with only about half the eventual benefit visible in the first year of treatment. This consistency undercuts arguments that drug benefits come from something other than LDL lowering, such as pleiotropic effects.
Reviving obicetrapib at New Amsterdam Pharma 40:00
After selling his previous company, an interleukin-6 antibody firm whose Zeus trial is due out this year, the speaker teamed up with John to acquire obicetrapib from Amgen, which had shelved the drug after Repatha's slow launch despite having completed phase two work and manufacturing improvements. The team initially considered targeting statin-intolerant patients but abandoned that path because the FDA is skeptical that statin intolerance is a genuine, common condition. Instead they pursued a full LDL-lowering approval pathway requiring an outcome study. Early phase two data, called the Tulip study, showed 45 percent LDL lowering and 150 percent HDL raising at a 10 milligram dose over just 8 to 12 weeks, making obicetrapib far more potent than earlier CETP inhibitors.
HDL raising and dysfunctional high HDL 46:01
Mendelian randomization studies, including a Nature paper from around 2012, showed that genes raising HDL alone provide no protection unless they also affect LDL or triglycerides, and some HDL-raising genes, like SRB1, actually increase risk, as does alcohol. This means a high HDL reading does not guarantee safety, illustrated by a patient with HDL around 100 to 110 and moderate LDL who assumed he was risk-free but was found to have significant plaque burden on a CT angiogram, likely due to dysfunctional HDL from an SRB1 variant common in Ashkenazi Jewish populations. The team remains hopeful that obicetrapib's HDL-raising effect could still contribute benefits, particularly around diabetes prevention and Alzheimer's disease, which are being studied separately from its LDL-lowering effects.
Obicetrapib's phase three results and Prevail trial 50:00
Obicetrapib's phase three program, including the Rose and Rose 2 trials, confirmed 45 to 50 percent LDL lowering as monotherapy and about 55 percent combined with ezetimibe. In the Brooklyn trial of familial hypercholesterolemia patients already on maximal therapy with LDL around 100, obicetrapib lowered LDL by an additional 40 percent, down to about 60. The Broadway trial, in atherosclerotic cardiovascular disease patients on high-intensity statins, showed roughly a 35 percent LDL reduction and, notably, a 21 percent reduction in major adverse cardiac events within one year, becoming significant once the first six months were excluded from analysis. This result is now being tested at scale in the Prevail trial, a global study of 9,500 patients with atherosclerotic cardiovascular disease, expected to reach its minimum two and a half year followup by the end of this year, with results also depending on accumulating enough cardiac events to power the analysis. Europe does not require the outcome trial for approval since it accepts LDL lowering itself as sufficient evidence, while the United States does require it.
Discordance Between LDL Particle Measures 56:01
The conversation turns to a puzzle from the Rose 2 trial, where LDL cholesterol lowering, LDL particle number by NMR, and apoB lowering did not move together, with apoB lowering notably more modest, around 16 percent. Michael explains he prefers LDL particle number over apoB partly because discordance shows up more clearly with it, since you can see a normal apoB reading alongside a very high particle count. He attributes this to the fact that apoB is a mass assay while LDL particle number comes from nuclear magnetic resonance, and smaller particles carry sugar molecules attached to the protein that change the measured mass without changing particle count. He notes obesetrapib, as a CETP inhibitor, wipes out small particles by 90 percent while apoB does not fall as much as expected, and his team is studying UK Biobank data to see which measure better tracks actual risk.
Non-HDL Cholesterol and Outcome Prediction 1:00:01
Michael brings up non-HDL cholesterol, which is LDL plus VLDL cholesterol, as a measure closely tied to apoB and highly correlated with the benefit seen in the Merck REVEAL trial. He acknowledges a paper from roughly six years ago in JAMA or the New England Journal of Medicine that favored apoB over non-HDL cholesterol, while other studies have shown the opposite, so evidence goes both ways. He argues that non-HDL, apoB, and LDL particle number mostly tell the same story, with non-HDL being the cheapest option and the other two offering slightly more precision at the cost of an extra lab test. He states that obesetrapib's apoB lowering already supports an outcome benefit in the PREVAIL trial, but the drug performs even better when judged by non-HDL cholesterol.
Lipoprotein(a) Lowering Effect 1:01:01
Obesetrapib lowers lipoprotein(a), often written Lp(a), by about 50 percent, more than PCSK9 inhibitors achieve, though the range spans 50 to 150 depending on starting levels. The mechanism is not fully understood, similar to how it is unclear why PCSK9 inhibitors lower Lp(a) by 15 to 20 percent. Michael's team ran a clearance and synthesis labeling study suggesting the drug reduces Lp(a) production, though the study was small. He notes other CETP inhibitors showed similar but smaller effects.
The Horizon Trial and Lp(a) Causality 1:02:32
The antisense oligonucleotide drug targeting Lp(a), tested in the Horizon phase three trial, is expected to report this year. The trial was extended rather than stopped for futility, and it showed a lower than expected event rate, which Michael attributes to LDL already being brought down to 60 in that trial population, mitigating risk before the Lp(a) drug's effect could be isolated. Peter suggests the low event rate simply meant not enough events accumulated in the time frame studied, not that lowering Lp(a) doesn't matter. Both agree the results, whenever they arrive, will speak to whether Lp(a) is a causal risk factor.
Where Obesetrapib Fits Alongside Statins 1:05:00
Statins lower LDL, are generic, and are well tolerated, but they raise Lp(a) slightly, raise diabetes risk slightly, and don't lower small particles well. Obesetrapib complements these gaps by lowering diabetes risk, lowering Lp(a) by roughly 50 percent, and cutting small particles by 90 percent, positioning it as a natural companion drug after statins, with a combination pill with ezetimibe available for patients needing more potency. Michael estimates 90 percent of patients could have their lipid treatment resolved with obesetrapib alone or combined with ezetimibe.
Concerns About High-Dose Statins and Drug Pricing 1:06:30
Peter raises concern that high-dose statins combined with ezetimibe can raise liver transaminases more often than the literature reports, even when guidance says increases under three times normal can be ignored. Michael shares the concern and dislikes high-dose statins generally, referencing a figure from Tom Dayspring showing that benefit flattens sharply after the lowest statin doses. On pricing, Michael avoids committing to a number for obesetrapib but stresses that access depends on how pharmacy benefit managers structure rebates, contrasting the low price of branded Zetia with the high cost of Nexletol, which he calls barely effective and inaccessible at 6000 dollars a year.
Origins of the Alzheimer's Hypothesis 1:12:01
Michael describes how the Alzheimer's angle began with Mendelian randomization data from the Bronx Aging Study, where among roughly 400 Ashkenazi Jews living past 100, the most common gene variant was CETP loss of function, associated with high HDL. Later data showed that among people carrying APOE4, having a CETP loss of function variant sharply reduced Alzheimer's risk, essentially erasing the elevated risk that APOE4 usually confers. This was reinforced by animal studies at McGill, where mice given the amyloid precursor protein gene developed worse dementia when also given the CETP gene, and improved when treated with a CETP inhibitor. With this evidence, Michael pushed to study Alzheimer's at New Amsterdam, though funding was scarce since Alzheimer's drug development is notoriously difficult; the company still allocated 1 million dollars early on, later running a small Amsterdam study of about 13 APOE4 carriers with mild cognitive impairment who received obesetrapib and showed improvements in lipid metabolism.
How APOE4 Damages Brain Cholesterol Handling 1:18:00
The brain is extremely cholesterol-rich, with roughly 2 percent of its dry weight accounting for half the body's cholesterol, much of it locked into myelin, which is about 50 percent cholesterol. The blood-brain barrier completely isolates brain lipid metabolism from the rest of the body, so there is no apoB or LDL in the brain, only APOE and HDL-like particles; a liver transplant that changes someone's peripheral APOE type does not change the APOE type in their brain. Astrocytes produce APOE, and in APOE4 carriers this protein poorly clears cholesterol from neurons, letting toxic cholesterol byproducts like 24-hydroxycholesterol build up and trigger inflammation, followed by amyloid and tau pathology, the classic markers Alzheimer first described. Carrying one APOE4 copy brings Alzheimer's on roughly 10 years earlier, and two copies about 20 years earlier, with homozygous E4 carriers facing about ten times the average risk, heterozygous E3/E4 about three times, and APOE2 carriers enjoying lower risk and greater longevity.
HDL as the brain's cleanup system 1:24:30
The discussion returns to why HDL matters for the brain even though it cannot cross the blood-brain barrier the way LDL particles do. The receptor SRB1, which interfaces with HDL, is heavily present in the blood-brain barrier and the choroid plexus, meaning HDL is essentially the only outside molecule that interacts with the brain. Raising HDL is thought to help remove excess cholesterol that APOE4 carriers cannot metabolize well, deliver antioxidants, reduce inflammation, and possibly even help clear amyloid. This is the basis for believing that raising HDL through obicetrapib's mechanism could ease APOE4-related Alzheimer's risk, and the same underlying process is thought to happen in non-carriers too, just later in life, around the 80s or 90s instead of the 60s or 70s.
Statins and Alzheimer's risk 1:27:30
Asked whether statins crossing the blood-brain barrier could theoretically worsen Alzheimer's risk by lowering brain cholesterol, the guest says the major statin trial looking at Alzheimer's showed no benefit, essentially a wash, though this doesn't prove statins can't help. An observational study found lower dementia risk in APOE4 carriers taking statins, but that data is fraught with issues compared to secondary analyses of randomized trials. Secondary analyses across statin trials tend to show a reduction in dementia broadly, which is suspected to reflect improvement in vascular dementia rather than a specific effect on Alzheimer's biology, since these trials are not designed to separate dementia subtypes.
Early biomarker results from the pilot study 1:29:00
A pilot study measured cerebrospinal fluid in patients with mild cognitive impairment and found reductions in 24-hydroxycholesterol and 27-hydroxycholesterol sterols, an effect not seen with statins. The study also showed stabilization of biomarkers, stable cognition, and a few anecdotal cases of real cognitive benefit, along with rising antioxidant levels in the fluid. Although open-label and not powered for definitive conclusions, this was treated as proof that the drug was engaging its target and clearing potentially toxic sterols.
Alzheimer's as a decades-long disease 1:31:01
The conversation frames Alzheimer's as a disease of middle age that only presents in old age, since abnormal biology can begin roughly twenty years before mild cognitive impairment appears. By the time functional impairment or MCI shows up, the brain has already shrunk and neurodegeneration has set in, meaning treatment at that stage is likely too late, paralleling how lowering LDL no longer helps once someone already has heart failure. This is offered as an explanation for why Alzheimer's drug development has been such a graveyard: without an equivalent of a survivable heart attack that allows secondary prevention trials, pharma has been forced to test drugs on people who are already too far gone.
Comparing tau biomarkers ptau217 and ptau181 1:35:02
Ptau217 and ptau181 are both tau measurements that strongly predict amyloid levels seen on PET scans, potentially making PET scans less necessary given their cost and radiation exposure. Ptau217 appears slightly earlier in disease progression than ptau181, and a newer marker called brain-derived ptau may be even better, though still early. The disease sequence runs from amyloid buildup first, then conversion to tau pathology, which is what actually drives neurodegeneration later on. Currently ptau217 is only regulator-approved as a ratio with amyloid beta 40, not as a standalone marker, while ptau181 and amyloid beta 42/40 are approved individually.
Trial results across biomarkers and subgroups 1:40:00
In the Broadway trial of about 2,500 heart disease patients averaging 65 years old, a prespecified analysis of biomarkers at baseline and 12 months found an overall reduction in rising ptau217, with stronger effects in older patients, APOE4 carriers, and especially E4 homozygotes, who showed over a 20 percent difference from placebo along with improvement across ptau181, amyloid 42/40, GFAP, and neurofilament light. Because ptau217 alone cannot yet serve as a regulatory endpoint without demonstrated cognitive improvement, the guest sees the biggest challenge as convincing regulators and the field, still largely fixated on amyloid, that a biomarker like this deserves surrogate approval status, similar to precedents in other rare diseases. A next planned 300-patient study will target people with elevated tau evidence before MCI onset, since MCI is considered comparable to early heart failure, already too late to reverse the underlying damage.
Omega-3s and cardiovascular risk 1:50:30
The conversation shifts to omega-3 fatty acids, DHA and EPA, starting with cardiovascular disease. The guest recalls developing an omega-3 drug called Epanova, mostly EPA with some DHA, tested in an outcome study called the Strength trial at a four gram dose, which did not succeed. He explains there are two plausible mechanisms for omega-3s lowering cardiovascular risk: triglyceride lowering, and an anti-thrombotic, anti-inflammatory effect from EPA antagonizing the arachidonic acid pathway, with the Strength trial having been set up mainly to test the triglyceride-lowering pathway.
Fish Oil Trial Placebo Controversies 1:52:00
The REDUCE-IT trial used mineral oil as a placebo, and there is a hypothesis that mineral oil itself slightly increased cardiovascular events, which may have made the EPA-only drug look better than it truly was, partly by raising inflammatory signaling and possibly interfering with statin absorption, since LDL levels in the placebo group rose about 9 to 10 percent. Even accounting for that distortion, Michael still believes pure EPA showed a real benefit. The STRENGTH trial, which combined EPA and DHA and used inert corn oil as the placebo, did not show an overall benefit, though there may have been a signal in the secondary prevention subgroup. The PROMINENT trial, testing a triglyceride-lowering fibrate called pemafibrate, also showed no benefit, reinforcing the idea that EPA's benefit comes from an anti-atherosclerotic, anti-inflammatory effect rather than from lowering triglycerides.
DHA Transport Into The Brain 1:54:31
DHA is the dominant fatty acid in the brain, but direct DHA supplementation has not shown clear cognitive benefits, partly because APOE4 carriers have a genuine DHA deficiency in the brain. A newly identified transporter called MFSD2A moves DHA across the blood-brain barrier, and it turns out this transporter prefers a specific chemical form called lysoPC-DHA rather than ordinary DHA. Since the brain cannot make much of its own DHA, it depends on this transport route, and a lysoPC-DHA supplement is now being developed, with Michael's group planning studies through Jocasta to test whether it actually crosses into the brain. His current view is that someone with low omega-3 levels who raises their red blood cell EPA and DHA to around 10 percent through standard supplements likely lowers cardiovascular risk but probably does not meaningfully lower Alzheimer's risk, because the ordinary supplement can't convert efficiently into the lysoPC form the brain needs.
AI’s Potential In Clinical Trials 1:58:00
Michael sees the biggest possible impact of AI on medicine not in diagnostics but in shrinking the cost and time of clinical trials, potentially from four billion dollars and ten years down by an order of magnitude. He argues trials are diluted by non-compliant patients under intention-to-treat analysis, and that AI could help identify and model outcomes based on patients who actually took the drug correctly, similar to per-protocol analysis, though the FDA currently won't accept that approach. Roughly 80 percent compliance is considered the benchmark for a well-run trial. He also notes that LDL-lowering trials are becoming harder to run ethically, since so many effective drugs already exist and patients can't be denied access to them.
Statins And Insulin Resistance 2:01:31
Almost all LDL-lowering drug classes, including statins and PCSK9 inhibitors, show a small increase in diabetes or insulin resistance risk, except obicetrapib. Mendelian randomization data support a general LDL-lowering to diabetes-risk link, though bile acid sequestrants are an exception, likely because forcing the body to resynthesize bile acids consumes extra energy. The mechanism remains unclear, but the effect appears dose-, age-, and weight-related, arguing for lower statin doses combined with other agents rather than maximal statin therapy. Despite this signal, the cardiovascular benefit of LDL lowering vastly outweighs the diabetes risk.
Obicetrapib’s Development And Cost 2:06:01
No other CETP inhibitors are currently in development, leaving obicetrapib essentially alone in its class; it originated at Mitsubishi in Japan, was later acquired by Amgen, and was designed as an improved, low-dose, highly bioavailable, more potent version of earlier CETP inhibitors. Developing it, including acquisition and trial costs, has run well over a billion dollars, consistent with the roughly three to four billion dollar average cost of bringing a drug to approval.
Biotech Investment Landscape 2:08:32
Michael sees biotech in a strong position despite AI dominating investor attention, because large pharmaceutical companies face patent cliffs and have grown less innovative, leaving room for smaller, more nimble companies. He notes China's enormous chemist workforce, roughly ten times that of the United States, giving it strong manufacturing and development capacity, as seen when a Chinese company, WuXi, solved manufacturing problems for the drug klotho after others could not.
Klotho’s Uncertain Mechanism 2:12:31
Klotho research has genomic validation, animal and primate data showing improved cognition, and publication in Nature, but its mechanism of action remains unknown, something true of only a small fraction of FDA-approved drugs like metformin or Tylenol. Researchers now suspect a cleaved fragment of klotho, rather than the full-length protein, crosses the blood-brain barrier, and human trials are expected within about a year following an IND filing.
Living With APOE4 2:16:00
Michael shares that he recently lost a double first cousin, an APOE4 carrier, to Alzheimer's at age 72, reinforcing his view that knowing your APOE4 status is worthwhile because it can motivate better lifestyle choices around exercise, blood pressure, diabetes prevention, and possibly DHA intake, even without a cure. Both speakers close by expressing hope that klotho and obicetrapib, working through different mechanisms, might eventually offer complementary strategies against Alzheimer's and cardiovascular disease, while acknowledging multiple therapies will likely be needed.
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