Alzheimer’s Disease Beyond Amyloid: What Atherosclerosis Teaches Us About Dementia Risk

For more than three decades, amyloid has been the organizing principle of Alzheimer’s disease research. The sticky protein fragment, which accumulates into plaques in the brain years before memory problems appear, has defined how the disease is diagnosed biologically, how biomarkers are developed, and how new therapies are designed. Yet a growing body of evidence now argues that amyloid, while necessary to define the disease, is not sufficient to explain it. People with nearly identical amyloid burdens can follow strikingly different clinical paths, from lifelong cognitive resilience to rapidly progressive dementia. A new perspective published in Annals of Clinical and Translational Neurology proposes that the field should look to an unlikely teacher for guidance on this puzzle: atherosclerosis, the artery-clogging process behind heart attacks and strokes.

The analogy is more than rhetorical. Cardiovascular medicine underwent its own conceptual revolution after discovering that the sheer size of an atherosclerotic plaque poorly predicts who will have a heart attack. Many severely narrowed arteries remain silent for life, while acute events often arise from lesions causing only modest narrowing. What matters is not the presence of plaque but its biological behavior: inflammatory activity, lipid composition, the integrity of the fibrous cap, neovascularization, intraplaque hemorrhage, endothelial dysfunction, and thrombotic susceptibility. Cardiovascular risk is now understood as a dynamic interplay between the pathological substrate and systemic modifiers, including age, genetics, hypertension, diabetes, dyslipidemia, obesity, smoking, chronic inflammation, physical inactivity, diet, and environmental exposures. Plaque detection marks increased biological risk, not an inevitable cardiac event.

Alzheimer’s disease, the authors argue, has reached the same stage of conceptual maturity. Amyloid accumulation may initiate or facilitate downstream processes, but the transition from biological pathology to clinical dementia is shaped by their interaction with tau propagation, neuroinflammation, synaptic dysfunction, cerebrovascular injury, metabolic alterations, genetic susceptibility, co-existing pathologies, and mechanisms of resilience. Within this framework, amyloid remains indispensable to the biological definition of Alzheimer’s disease, but its clinical significance depends on the biological context in which it occurs. This multidimensional view helps explain why individuals with comparable amyloid burden can follow markedly different trajectories, and why amyloid positivity alone does not equate to clinical Alzheimer’s disease.

Some of the strongest evidence that amyloid and dementia can be uncoupled comes, paradoxically, from the population in which the amyloid cascade hypothesis is best supported: carriers of autosomal dominant Alzheimer’s mutations. In the Colombian PSEN1 E280A kindred, the largest such family in the world, affected members typically develop mild cognitive impairment around age 44 and dementia around age 49, with amyloid deposition detectable more than two decades before symptoms. Yet within this genetically homogeneous cohort, two carriers have been reported who accumulated amyloid burdens comparable to or exceeding those of their symptomatic relatives but remained free of dementia for decades beyond the expected age of onset. One, homozygous for the rare APOE3 Christchurch variant, showed high amyloid-PET signal but limited tau spread and cortical atrophy, and did not develop dementia until her seventies, roughly three decades later than expected. A second, carrying a rare RELN variant, showed a similarly protected trajectory. In both cases, protection appears to act downstream of amyloid, limiting tau propagation and the associated neuroinflammatory and neurodegenerative cascade.

This principle extends well beyond rare genetic forms of the disease. Population-based cohorts and biomarker studies consistently show that a substantial proportion of cognitively unimpaired older adults fulfill biological criteria for Alzheimer’s disease while remaining clinically normal for prolonged periods. A meta-analysis of biomarker-defined cohorts found that amyloid positivity increased the risk of clinical progression, but that this risk rose markedly when concomitant tau pathology was present. Amyloid positivity, in other words, identifies a state of increased biological susceptibility rather than an inevitable clinical destiny, much as plaque presence flags vascular risk without dictating a heart attack.

Therapeutic trials reinforce the same lesson. Anti-amyloid monoclonal antibodies such as lecanemab and donanemab have unequivocally demonstrated that cerebral amyloid can be substantially reduced in living brains. Across pivotal Phase III trials, treatment slowed cognitive decline but did not arrest disease progression, and clinical benefits have been consistently modest relative to the magnitude of amyloid removal. The authors caution that these results should not be read as a failure of the amyloid hypothesis. Rather, they suggest that amyloid removal alone may be insufficient once downstream cascades, including tau spread, synaptic dysfunction, neuroinflammation, and neuronal loss, have become established. Modifying the pathological substrate does not necessarily abolish the network of mechanisms ultimately responsible for cognitive decline, just as clearing one plaque does not eliminate the systemic biology of cardiovascular disease.

Community-based neuropathological studies add a further, often underappreciated, dimension. Unlike clinic-based autopsy series, cohorts such as the Religious Orders Study, the Rush Memory and Aging Project, and the Medical Research Council Cognitive Function and Ageing Study examine brains irrespective of ante-mortem diagnosis, offering a more representative picture of brain aging. These studies consistently show that pure Alzheimer’s disease is the exception rather than the rule in older adults. Most individuals with dementia harbor multiple co-existing pathologies, including cerebrovascular disease, Lewy body pathology, limbic-predominant age-related TDP-43 encephalopathy, hippocampal sclerosis, and argyrophilic grain disease. Crucially, co-pathologies are not incidental: each additional pathology lowers the threshold of Alzheimer’s neuropathologic change required for clinically overt dementia, while individuals with substantial amyloid but limited co-existing disease may remain cognitively preserved.

The authors also elevate the concept of biological resilience, distinguishing it from brain reserve, the structural capacity to tolerate pathology, and cognitive reserve, the ability to sustain performance through more efficient neural networks shaped by education and cognitive engagement. Biological resilience refers instead to intrinsic molecular, cellular, vascular, and immunological mechanisms that limit the pathological consequences of Alzheimer’s disease despite the presence of its defining lesions. Evidence is accumulating rapidly: the protected Colombian carriers demonstrate that extensive amyloid can coexist with preserved cognition when tau spread is restrained, and genetic modifiers such as APOE, RELN, and microglial genes like TREM2 show that resilience is partly biologically encoded. Resilience likely emerges from the interaction of many systems, including tau propagation control, synaptic integrity, innate immune regulation, blood-brain barrier maintenance, cerebrovascular health, mitochondrial function, proteostasis, and metabolic homeostasis.

This framework also reframes the meaning of modifiable risk factors. The 2024 Lancet Commission on dementia prevention identified 14 potentially modifiable factors, including lower educational attainment, hearing loss, high LDL cholesterol, depression, traumatic brain injury, physical inactivity, diabetes, smoking, hypertension, obesity, excessive alcohol consumption, social isolation, air pollution, and untreated vision loss. Viewed through the new lens, these are not merely contributors to dementia risk but determinants of the brain’s resilience or vulnerability to Alzheimer’s pathology. Hypertension, diabetes, obesity, dyslipidemia, smoking, and air pollution promote endothelial dysfunction, blood-brain barrier impairment, cerebrovascular injury, oxidative stress, and chronic inflammation, lowering the threshold at which amyloid translates into neuronal dysfunction. Conversely, education, cognitive stimulation, physical activity, social engagement, and preserved sensory function help the brain tolerate pathological burden. The parallel with cardiology is direct: plaque identifies the underlying disease, but systemic risk factors determine whether it ever produces an event.

The practical implication is a shift from biological diagnosis to biological risk stratification. Current NIA-AA criteria answer with remarkable precision whether an individual has biological Alzheimer’s disease, but they are not designed to answer who will progress, when, or through which pathways. The authors propose that once biological Alzheimer’s disease is established, clinical decision-making should integrate amyloid and tau biomarkers with measures of neurodegeneration, cerebrovascular injury, co-existing proteinopathies, neuroinflammation, genetic susceptibility, metabolic health, and cognitive reserve to estimate the probability and pace of clinical conversion. The next frontier, they conclude, is not to move beyond amyloid but to move beyond an amyloid-centric interpretation of the disease. If amyloid defines the biological identity of Alzheimer’s disease, resilience may ultimately define its clinical destiny, and integrating pathological burden with the determinants of resilience and vulnerability could provide the foundation for truly personalized prediction, prevention, and treatment.

Subject of Research: A conceptual framework comparing Alzheimer's disease progression beyond amyloid pathology with atherosclerosis risk biology

Article Title: Alzheimer's Disease Beyond Amyloid: Lessons From Atherosclerosis

Article References: Ciaccio, M., & Agnello, L. (2026). Alzheimer's Disease Beyond Amyloid: Lessons From Atherosclerosis. Annals of Clinical and Translational Neurology, Article acn3.70533. https://doi.org/10.1002/acn3.70533

Image Credits: AI Generated

DOI: 10.1002/acn3.70533

Keywords: Alzheimer's disease, amyloid, tau, atherosclerosis, biological resilience, biomarkers, neuroinflammation, cerebrovascular disease, Lancet Commission, anti-amyloid therapies, mixed neuropathology, precision medicine