Understanding neurodegenerative disease in diverse global populations remains a major priority for modern clinical neurology and geriatrics. Historically, Western cohorts have dominated post-mortem neuropathology literature, leaving significant knowledge gaps regarding East Asian populations. A landmark autopsy study from the National Human Brain Bank for Development and Function at the Chinese Academy of Medical Sciences and Peking Union Medical College has provided crucial insights into neuropathological comorbidity in older adults. By examining brain tissue from 610 community-dwelling Chinese participants, researchers delineated how overlapping neurodegenerative pathologies interact with age, genetics, and clinical cognitive function. Consequently, these findings reshape how clinicians understand mixed dementia and therapeutic stratification in clinical practice.

Landscape of Neuropathological Comorbidity in Older Adults

In clinical practice, physicians often diagnose dementia as a single, isolated disease entity such as Alzheimer's disease or Parkinson's disease. However, human autopsy data consistently reveals that pure pathology represents an exception rather than the standard rule. In this comprehensive cohort of 610 individuals, multiple concurrent neurodegenerative changes were remarkably frequent across the aging spectrum.

Specifically, researchers evaluated eight major pathological entities, including Alzheimer's disease neuropathological change (ADNC), alpha-synucleinopathies, limbic-predominant age-related TDP-43 encephalopathy neuropathological changes (LATE-NC), and primary age-related tauopathy (PART). Additionally, investigators tracked argyrophilic grain disease (AGD), age-related tau astrogliopathy (ARTAG), cerebral amyloid angiopathy (CAA), and hippocampal sclerosis (HS).

Notably, advanced age at death demonstrated a robust positive correlation with pathological severity and the total burden of neuropathological comorbidity. As individuals lived longer, their brains accumulated greater numbers of distinct proteinopathies and vascular lesions simultaneously. Furthermore, frontotemporal lobar degeneration and amyotrophic lateral sclerosis remained relatively uncommon in this community cohort. These observations highlight that multi-protein deposition constitutes an inevitable biological hallmark of brain aging, urging clinicians to rethink single-target therapeutic paradigms.

Prevalence of ADNC, LATE-NC, and Related Pathologies

The distribution of specific neurodegenerative markers within this Chinese cohort provides vital epidemiological baseline data. Among the 610 post-mortem cases, LATE-NC emerged as the most prevalent pathology, affecting 341 individuals. ADNC followed closely behind, identified in 331 cases across varying stages of severity.

Primary age-related tauopathy appeared in 231 participants, while cerebral amyloid angiopathy was confirmed in 183 brains. Furthermore, ARTAG was identified in 144 individuals, and alpha-synucleinopathies were observed in 124 cases, predominantly comprising Lewy body disease (120 cases) alongside a small number of multiple system atrophy cases (4 cases). Argyrophilic grain disease appeared in 107 brains, whereas hippocampal sclerosis was documented in 46 participants.

Interestingly, PART presented the highest rate of pure pathology, with 37.2% of PART cases lacking other significant neurodegenerative lesions. In contrast, other conditions rarely existed in isolation. For instance, LATE-NC and ADNC demonstrated extensive overlap, where advancing stages of one pathology reliably predicted the co-occurrence of the other. Therefore, clinicians must recognize that TDP-43 proteopathy and amyloid-tau cascades frequently converge within the aging brain, compounding structural and functional neurological injury.

Genetic Influences: The Role of the APOE ε4 Allele

Genetic architecture plays a fundamental role in dictating susceptibility to neurodegeneration and comorbid proteinopathies. In this autopsy cohort, the overall allelic frequency of APOE ε4 was 13.63%. Although this frequency aligns with general East Asian population estimates, its presence exerted profound pathological consequences.

Statistical regression analyses demonstrated that carrying at least one APOE ε4 allele significantly correlated with more advanced ADNC stages. Moreover, APOE ε4 carriers exhibited a markedly higher overall burden of comorbid neuropathological lesions compared to non-carriers. Thus, the ε4 allele does not merely accelerate beta-amyloid deposition and neurofibrillary tangle spread; it also creates a permissive environment for multi-pathology accumulation.

These findings suggest that apolipoprotein E isoforms modulate broader neurobiological pathways, including neuroinflammation, blood-brain barrier integrity, and protein clearance mechanisms. Consequently, when clinicians evaluate patients with suspected cognitive decline, genetic screening for APOE status provides valuable predictive context. Carriers not only face elevated risks for classical Alzheimer's disease but also harbor heightened vulnerability to complex, mixed neurodegenerative pathologies that can accelerate cognitive decline.

Synergistic Interactions Across Neurodegenerative Subtypes

Rather than developing independently, distinct neurodegenerative pathologies display powerful cross-seeding and synergistic progression. Within the ADNC subgroups of this study, the prevalence of Lewy body disease, LATE-NC, cerebral amyloid angiopathy, and hippocampal sclerosis increased sharply as ADNC severity worsened.

Similarly, within LATE-NC subgroups, higher pathological stages correlated with increased rates of ADNC, CAA, and ARTAG, whereas the frequency of pure PART declined markedly. These bidirectional relationships demonstrate that one proteinopathy actively facilitates the propagation of another. Furthermore, cases exhibiting neocortical Lewy body disease showed significantly elevated ADNC levels, and higher LATE-NC stages correlated with worsening Lewy body pathology.

This biological synergy suggests shared pathogenic pathways, such as impaired autophagic clearance, microglial senescence, and neurovascular unit disruption. Therefore, treating a single abnormal protein aggregate might prove insufficient to arrest global disease progression. Instead, therapeutic interventions may ultimately require combination regimens targeting multiple concurrent molecular cascades to achieve meaningful clinical neuroprotection.

Impact of Neuropathological Comorbidity on Cognitive Decline

The clinical relevance of post-mortem neuropathology centers on its ultimate correlation with antemortem cognitive function. In this cohort, researchers identified three independent predictors of severe cognitive impairment: high-level ADNC, neocortical Lewy body disease, and stage 3 LATE-NC.

When these pathologies occurred concurrently, their combined deleterious impact on cognitive domains proved additive and profound. Patients with isolated, mild pathology frequently preserved cognitive resilience throughout late life. Conversely, individuals who accumulated multi-target proteinopathies suffered steep, progressive functional decline. Hippocampal sclerosis and widespread vascular changes like CAA also exacerbated memory loss and executive dysfunction.

These findings clarify why many clinical trials targeting isolated amyloid-beta plaques have demonstrated modest cognitive efficacy in real-world geriatric populations. Because advanced dementia frequently stems from mixed pathology rather than pure Alzheimer's disease, unmeasured LATE-NC or neocortical Lewy bodies continue to drive synaptic loss. Hence, accurate prognostic counseling demands an appreciation of how cumulative comorbid lesions erode cognitive reserves.

Clinical Implications for Geriatric Neurology and Practice

Translating these post-mortem findings into daily clinical practice requires a paradigm shift for neurologists, geriatricians, and primary care physicians. Mixed dementia must be considered the default diagnostic hypothesis in older adults presenting with progressive cognitive decline, especially beyond the eighth decade of life.

Clinicians should routinely assess for atypical features that suggest comorbid pathologies. For example, rapid progression, early visual hallucinations, REM sleep behavior disorder, or prominent autonomic dysfunction point toward concurrent Lewy body pathology. Similarly, disproportionate amnesia in the presence of modest biomarker-confirmed amyloid burden may signal co-existing LATE-NC or hippocampal sclerosis.

Furthermore, management strategies must prioritize comprehensive risk factor modification. Optimizing vascular health, managing metabolic parameters, and avoiding anticholinergic medications help maintain neural resilience against underlying proteinopathies. As targeted disease-modifying therapies continue to enter clinical medicine, fluid and imaging biomarkers capable of detecting multi-pathology in vivo will become indispensable for selecting appropriate patient candidates.

What is the most common neuropathological finding in this Chinese autopsy cohort?

In this cohort of 610 participants, limbic-predominant age-related TDP-43 encephalopathy neuropathological changes (LATE-NC) represented the most frequent finding, observed in 341 individuals. Alzheimer's disease neuropathological change (ADNC) was the second most prevalent condition, occurring in 331 participants, often overlapping with LATE-NC and vascular pathologies.

How does the APOE ε4 allele influence neuropathological comorbidities?

The APOE ε4 allele significantly accelerates Alzheimer's disease neuropathology and increases the total burden of concurrent neurodegenerative comorbidities. Carrying the ε4 allele promotes an environment vulnerable to multiple proteinopathies, linking genetic risk not only to amyloid deposition but also to mixed pathological progression and faster cognitive decline.

Which neuropathological lesions independently predict severe cognitive impairment?

Multivariate regression analyses identified high-level Alzheimer's disease neuropathological change, neocortical Lewy body disease, and stage 3 LATE-NC as the three independent predictors of severe cognitive status. When these distinct pathologies co-exist, they synergistically impair synaptic connectivity, leading to accelerated memory loss and profound functional dementia.

Disclaimer: This content is for informational and educational purposes only and is not intended as medical advice. Healthcare professionals should exercise their independent clinical judgment. Refer to the latest local and national guidelines for clinical practice.

References

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2. Wang X, Zhu K, Wu W, et al. Prevalence of mixed neuropathologies in age-related neurodegenerative diseases: a community-based autopsy study in China. Alzheimers Dement. 2025;21(1):e14369.


3. Boyle PA, Yu L, Leurgans SE, et al. Much of late life cognitive decline is not due to common neurodegenerative pathologies. Ann Neurol. 2018;84(2):281-289.