Topol explains why heart disease remains the leading global cause of death, despite decades of medical progress. Once projected to decline relative to cancer, heart disease has resurged since 2019, now killing about 100,000 more Americans each year than cancer. In 2021, the age-adjusted death rate from heart disease rose to 21 per 10,000 people, while cancer deaths fell to 14 per 10,000. Most Americans remain unaware that cardiovascular disease is still the top cause of death.

Topol traces the earlier decline in fatalities to major public health and clinical advances: reduced smoking rates, statin use, better hypertension management, and improved interventions like bypass surgery and stenting. However, the recent reversal reflects worsening lifestyle factors, especially the rise of obesity and diabetes (“diabesity”), combined with lapses in preventive care. He emphasizes that cardiovascular disease is highly preventable—up to 90% of cases could be avoided through healthier lifestyles.

The chapter focuses on atherosclerosis, the progressive accumulation of cholesterol-rich plaque within arteries. This process, which begins as early as adolescence, can lead to sudden heart attacks from plaque rupture or to chronic arterial narrowing. Smoking, hypertension, diabetes, and elevated LDL cholesterol accelerate its development. Screening advances such as CT angiography, calcium scoring, and emerging tools like proteomic and polygenic risk scores, as well as microbiome and inflammation markers, are enhancing early detection.

Drug treatments play a central role in prevention. Statins and newer therapies (e.g., PCSK9 inhibitors and RNA-based drugs) can dramatically lower LDL cholesterol, with some evidence favoring aggressive targets below 50 mg/dL. Triglyceride-lowering and apoB measurement provide additional insights into risk. Anti-inflammatory strategies, such as colchicine or monoclonal antibodies, have shown promise in reducing heart attacks and strokes, highlighting the role of systemic inflammation in cardiovascular disease.

Topol also discusses atrial fibrillation (AF), a common age-related arrhythmia and major cause of stroke. AF affects millions globally, with risks tied to age, obesity, sleep apnea, and other conditions. Polygenic risk scores, biomarkers, and AI-enhanced diagnostics improve detection, while GLP-1 drugs show benefits in reducing AF incidence. Ultimately, Topol stresses that prevention and early intervention are possible but underutilized, leaving untapped potential to suppress the world’s most important age-related cardiovascular diseases.

Topol argues that despite decades of breakthroughs in cancer biology, prevention, and treatment, approaches to cancer remain outdated, relying heavily on mid-20th-century paradigms. Cancer deaths are projected to nearly double by 2050, and nearly half of all people will develop some form of the disease in their lifetime. Effective expansion of human health span, Topol contends, cannot occur without confronting cancer more comprehensively.

Topol outlines three major theories of cancer origins: 1) the somatic mutation theory which holds that mutations originate in oncogenes and tumor-suppressor genes, 2) tissue-based causes such as carcinogenic exposure and disrupted immunity, and 3) random replication errors in stem cells (i.e. chance). Advances in spatial biology and single-cell sequencing now allow scientists to map tumors in 3D, revealing the evolution of cancer clones, tumor microenvironments, and metastatic spread. This work underscores that cancer often develops silently for years or decades, offering opportunities for early detection and intervention.

Despite these insights, treatment progress is slowed by delays in adopting molecularly targeted therapies. Mutation-specific drugs like PARP inhibitors or immunotherapies often take years to reach broader use, costing lives. Current screening protocols, based largely on age criteria, have two drawbacks: They detect relatively few cancers early, but create widespread false positives and overdiagnoses. Younger populations, meanwhile, are experiencing rising rates of late-stage cancers outside traditional screening guidelines.

Topol advocates for individualized, data-driven prevention strategies. Tools such as polygenic risk scores, whole genome sequencing, proteomic markers, inflammation assays, and AI-enabled interpretation of medical records and imaging can more accurately identify high-risk individuals. Emerging technologies, including liquid biopsies and multicancer early detection tests, offer promise but remain limited in accuracy and access.

Treatment is shifting toward precision medicine. Molecular characterization of tumors enables targeted drugs, antibody-drug conjugates, immunotherapies, engineered T cells (CAR-T), vaccines, and digital-twin models of care. These advances point toward a future of bespoke therapies. For now, prevention strategies—including lifestyle interventions, vaccines (e.g., HPV, hepatitis B), and targeted anti-inflammatory treatments—could significantly reduce incidence but are underutilized.

Topol concludes that while the knowledge exists to transform outcomes, cancer care remains constrained by outdated mass-screening methods and slow adoption of precision tools. Without integrating prevention, early detection, and individualized treatment, meaningful health span expansion will remain out of reach.

Topol surveys evolving understanding of brain aging and neurodegenerative diseases like Alzheimer’s and Parkinson’s, emphasizing breakthroughs in immune-brain interactions, biomarkers, and potential treatments.

For over a century, scientists believed the brain was “immune-privileged,” or isolated from the body’s immune system. Recent discoveries have overturned this, showing that the glymphatic system, skull bone marrow, and meninges act as conduits for immune surveillance. Specialized cells such as microglia, when impaired, contribute to inflammation, blood-brain barrier disruption, and synapse loss. Aging brains undergo structural shrinkage in gray and white matter, along with increased cerebrospinal fluid volume, changes now mapped through large MRI studies.

Alzheimer’s disease is the most studied disorder, with amyloid-beta and tau proteins central to its pathology. Amyloid plaques appear decades before symptoms, with tau-driven tangles worsening neural decline. Genetics play a strong role: The gene APOE4 is the strongest known risk factor, while protective alleles like APOE2 confer resilience. Advances in single-cell sequencing and genomics have expanded knowledge of the disease’s complex pathways. A major breakthrough came with blood biomarkers, particularly phosphorylated tau217, which rivals or surpasses spinal fluid tests and imaging in accuracy. Still, debates continue over how early and broadly such tests should be used.

Drug development has been marked by failure, particularly in amyloid-targeting therapies, though recent monoclonal antibodies (lecanemab, donanemab) have shown modest benefits with significant risks. Emerging approaches include gene therapy, tau-directed therapies, neurotrophin receptor modulators, and gut microbiome interventions. Prevention strategies emphasize early risk detection through genetics, biomarkers, and AI-enabled analytics, alongside lifestyle factors like exercise, diet, sleep, and social engagement. Environmental exposures—air pollution, heavy metals, and microplastics—are increasingly recognized as contributors.

Parkinson’s disease, the second most common neurodegenerative disorder, involves alpha-synuclein accumulation, mitochondrial dysfunction, and significant gut-brain interactions. Symptoms in the gastrointestinal system may precede motor symptoms by decades. Genetic risk is partly defined, and new biomarkers, including synuclein seed assays, are advancing early detection. Experimental therapies such as GLP-1 drugs, monoclonal antibodies, stem cell approaches, and fecal microbiota transplants, offer hope for slowing progression.

Topol closes by citing emerging work. Studies in mice suggest that factors from young blood, such as Klotho and platelet factor 4, may rejuvenate brain function. While no current therapies reliably prevent neurodegeneration, converging advances in biomarkers, genetics, AI, and novel treatments suggest that delaying or preventing cognitive decline may soon be possible.