#334 - Cardiovascular disease, the number one killer: development, biomarkers, apoB, cholesterol, brain health, and more | Tom Dayspring, M.D.

Episode Summary

Executive Summary: Peter Attia and Tom Dayspring give a dense, clinically grounded tour of ASCVD: how atherosclerosis begins in childhood, why ApoB particle number is the central causal driver, how triglycerides, saturated fat, insulin resistance, CKD, and Lp(a) amplify risk, and why HDL-C is an unreliable proxy. They also cover brain cholesterol biology, ApoE, and how to think about statins and cognition.

Main Topics: What atherosclerosis is and why it kills (Priority: 5/5): Atherosclerotic cardiovascular disease is defined as cholesterol deposition in artery walls, especially in small, high-demand vessels supplying the heart and brain, where plaque growth or rupture can cause ischemia, heart attack, stroke, or sudden death. Disease begins early and progresses over decades (Priority: 5/5): The speakers emphasize that atherosclerosis starts in childhood or even fetal life in familial hypercholesterolemia, but usually remains silent for decades before clinical events appear later in life. Risk factors: causal vs associative (Priority: 5/5): They distinguish causal risk factors such as age, smoking, ApoB, blood pressure, and likely CKD-related mechanisms from risk markers like hsCRP, calcium scoring, homocysteine, and other inflammatory biomarkers. ApoB as the key atherogenic particle metric (Priority: 5/5): ApoB is presented as the best practical measure of atherogenic particle number because each ApoB-containing lipoprotein carries one ApoB molecule; LDL, VLDL, IDL, remnants, and Lp(a) all fall under this umbrella. Triglycerides, saturated fat, and insulin resistance (Priority: 4/5): High triglycerides and saturated fat intake can worsen ApoB by reducing LDL receptor expression and increasing triglyceride-rich lipoproteins, while insulin resistance drives small dense LDL, remnant particles, and low HDL-C. HDL-C is not the same as HDL function (Priority: 4/5): HDL particles may be protective or dysfunctional depending on their proteome and phospholipid composition, but HDL cholesterol level alone does not reveal functionality or cardiovascular risk. Brain cholesterol, ApoE, and statins (Priority: 4/5): The brain synthesizes its own cholesterol, uses ApoE-containing lipoproteins for transport, and clears excess cholesterol via oxysterols. The discussion explores ApoE4, desmosterol, and why statins generally do not worsen cognition in population data.

Key Arguments: Atherosclerosis is fundamentally a cholesterol-dumping problem in the artery wall, not simply a blood cholesterol problem. The disease starts early in life, so prevention should begin with primordial prevention rather than waiting for symptoms or imaging. ApoB is the most useful routine biomarker because it counts the number of atherogenic particles, not just the cholesterol they carry. Smoking, hypertension, and endothelial injury increase the probability that ApoB particles enter and remain in the artery wall. CKD likely increases ASCVD risk through multiple mechanisms, including hypertension, dyslipidemia, homocysteine, uric acid, and other retained metabolites. Insulin resistance is tightly linked to atherogenic lipoprotein patterns and likely contributes to risk through both lipid and non-lipid pathways. High triglycerides are not the direct cause; they signal a lipoprotein remodeling state that increases ApoB particle number, remnant particles, and small LDL. Saturated fat can raise ApoB in susceptible people by downregulating hepatic LDL receptor expression and altering cholesterol synthesis. HDL-C is an unreliable surrogate because HDL function depends on particle composition, not cholesterol content. Lp(a) is a genetically determined, highly atherogenic ApoB-containing particle that should be measured at least once in life. Brain cholesterol is synthesized locally; peripheral LDL does not supply the brain, so lipid-lowering concerns about cognition should be individualized rather than assumed. Statins have not shown a consistent signal for worsening dementia in trials, but biomarkers like desmosterol may help in edge cases with cognitive vulnerability.

Data Points: ASCVD mortality ranking: #1 cause of death - Described as the leading cause of death in the U.S. and globally, in both men and women. First MI as sudden death: <50% fatal first MI - Peter notes the most recent estimate is slightly fewer than half of first myocardial infarctions are fatal. Men with first major cardiac event before 65: 50% - Among men who will have a major adverse cardiac event, half experience the first event before age 65. Women with first major cardiac event before 65: 33% - Among women who will have a major adverse cardiac event, one-third experience the first event before age 65. Atherosclerosis in childhood autopsies: Ages 4-8 - Autopsy studies found fatty streaks in the aorta of children as young as 4, 5, 7, and 8. Coronary/carotid occlusion before symptoms: 75-80% occluded - Brain and heart arteries may remain asymptomatic until severe narrowing is present. Lp(a) prevalence: ~20% - Tom states about 20% of people inherit the gene producing apolipoprotein(a). Lp(a) relative atherogenicity: 7-8x LDL particle - Lp(a) is described as particle-for-particle far more atherogenic than LDL. Brain cholesterol half-life: ~5 years - Cholesterol synthesized in the brain turns over far more slowly than plasma cholesterol. Brain cholesterol residence time: Up to 30 years - Using the stated half-life multiplier, some brain cholesterol molecules may persist for decades. Plasma cholesterol turnover: 2-3 days - Peripheral cholesterol turnover is much faster than in the brain. Triglyceride threshold for pathology: ~100 mg/dL - Tom argues triglyceride-related lipoprotein remodeling begins above about 100, not only at 150. Traditional triglyceride cutoff: 150 mg/dL - He criticizes the common lab threshold as too high and based on population percentiles. High-sensitivity CRP concern: >2 mg/L - Tom says values above 2 raise concern; above 4 suggest significant inflammation, though not specific to cardiovascular disease. Example calcium score: 10 - Peter cites patients with hsCRP <1 who still have a CAC score of 10, showing early disease can be missed by inflammation markers. LDL particle dominance in ApoB pool: ~95% - Tom says about 95% of ApoB particles are LDLs because of their long plasma residence time. ApoB in liver/intestine: Produced only by liver and small intestine - No other cells in the body produce ApoB. ApoA1 copies per HDL: 1-5 copies - This is why ApoA1 concentration is not a simple particle-count biomarker like ApoB. Statin brain-penetration view: All statins get into the brain - Tom says later analyses suggest both hydrophilic and lipophilic statins can reach the brain at steady state.

Pivotal Quotes: "If you don't, you don't have atherosclerotic heart disease." — Tom Dayspring: Defining the sine qua non of atherosclerosis as cholesterol in the artery wall. "ApoB is the ballgame nowadays." — Tom Dayspring: Explaining why ApoB is the most useful routine biomarker for atherogenic particle burden. "The goal of therapy is did I normalize ApoB." — Tom Dayspring: Clarifying that triglycerides and other markers are proxies, not the treatment target.

Implications: Listeners should focus on ApoB-centered prevention, not LDL-C or HDL-C alone. Earlier screening, especially in youth and high-risk families, plus aggressive lifestyle and selective pharmacology, can meaningfully reduce lifetime ASCVD risk.