graph LR
Triggering_of_Acute_Myocardial_Infarction["Triggering of Acute Myocardial Infarction"]
Endothelial_Dysfunction_and_Thromboinflammation["Endothelial Dysfunction and Thromboinflammation"]
Endothelial_Dysfunction_and_Thromboinflammation --> Triggering_of_Acute_Myocardial_Infarction
style Triggering_of_Acute_Myocardial_Infarction fill:#dbeafe
style Endothelial_Dysfunction_and_Thromboinflammation fill:#dbeafe
graph LR
Neuroinflammation["Neuroinflammation"]
Intercellular_Tau_Transmission_via_Extracellular_Vesicles["Intercellular Tau Transmission via Extracellular Vesicles"]
PSEN1["PSEN1"]
Synaptic_Dysfunction["Synaptic Dysfunction"]
Oxidative_Stress["Oxidative Stress"]
PARP1_Mediated_Parthanatos["PARP1-Mediated Parthanatos"]
HSV_1_Reactivation_in_RORB+_Glutamatergic_Neurons["HSV-1 Reactivation in RORB+ Glutamatergic Neurons"]
PSEN2["PSEN2"]
Memory_Loss["Memory Loss"]
Autophagy_Lysosomal_Dysfunction["Autophagy-Lysosomal Dysfunction"]
APP["APP"]
Amyloid_Plaque_Formation["Amyloid Plaque Formation"]
Mitochondrial_Quality_Control_Failure["Mitochondrial Quality-Control Failure"]
LRP1["LRP1"]
Neurofibrillary_Tangle_Formation["Neurofibrillary Tangle Formation"]
Vascular_Dysfunction["Vascular Dysfunction"]
Amyloid_Plaque_Formation --> Neurofibrillary_Tangle_Formation
Amyloid_Plaque_Formation --> Synaptic_Dysfunction
Amyloid_Plaque_Formation --> Neuroinflammation
Neurofibrillary_Tangle_Formation --> Synaptic_Dysfunction
Neurofibrillary_Tangle_Formation --> Intercellular_Tau_Transmission_via_Extracellular_Vesicles
Synaptic_Dysfunction --> Memory_Loss
Neuroinflammation --> Amyloid_Plaque_Formation
Neuroinflammation --> Neurofibrillary_Tangle_Formation
Neuroinflammation --> Oxidative_Stress
Neuroinflammation --> Vascular_Dysfunction
Oxidative_Stress --> Synaptic_Dysfunction
Mitochondrial_Quality_Control_Failure --> Amyloid_Plaque_Formation
Mitochondrial_Quality_Control_Failure --> Neurofibrillary_Tangle_Formation
Mitochondrial_Quality_Control_Failure --> Memory_Loss
Vascular_Dysfunction --> Amyloid_Plaque_Formation
Vascular_Dysfunction --> Synaptic_Dysfunction
Autophagy_Lysosomal_Dysfunction --> Amyloid_Plaque_Formation
Autophagy_Lysosomal_Dysfunction --> Neurofibrillary_Tangle_Formation
HSV_1_Reactivation_in_RORB+_Glutamatergic_Neurons --> Synaptic_Dysfunction
Intercellular_Tau_Transmission_via_Extracellular_Vesicles --> Neurofibrillary_Tangle_Formation
PARP1_Mediated_Parthanatos --> Neuroinflammation
PARP1_Mediated_Parthanatos --> Oxidative_Stress
PARP1_Mediated_Parthanatos --> Mitochondrial_Quality_Control_Failure
APP --> Amyloid_Plaque_Formation
PSEN1 --> Amyloid_Plaque_Formation
PSEN2 --> Amyloid_Plaque_Formation
LRP1 --> Vascular_Dysfunction
style Neuroinflammation fill:#dbeafe
style Intercellular_Tau_Transmission_via_Extracellular_Vesicles fill:#dbeafe
style PSEN1 fill:#f3e8ff
style Synaptic_Dysfunction fill:#dbeafe
style Oxidative_Stress fill:#dbeafe
style PARP1_Mediated_Parthanatos fill:#dbeafe
style HSV_1_Reactivation_in_RORB+_Glutamatergic_Neurons fill:#dbeafe
style PSEN2 fill:#f3e8ff
style Memory_Loss fill:#fef3c7
style Autophagy_Lysosomal_Dysfunction fill:#dbeafe
style APP fill:#f3e8ff
style Amyloid_Plaque_Formation fill:#dbeafe
style Mitochondrial_Quality_Control_Failure fill:#dbeafe
style LRP1 fill:#f3e8ff
style Neurofibrillary_Tangle_Formation fill:#dbeafe
style Vascular_Dysfunction fill:#dbeafe
name: com_Influenza__Alzheimer_Disease
creation_date: "2026-06-25T12:00:00Z"
curation_status: CANDIDATE
notes: >-
Tentative directional trajectory: severe influenza (notably influenza with
pneumonia) has been associated with later neurodegenerative disease, including
Alzheimer's disease and other dementias, in biobank and cohort studies. IMPORTANT
EVIDENCE CAVEAT: the Intercept essay cited "~4.5-5x dementia" and "~2.6-4.1x
Alzheimer's" risk after severe influenza/pneumonia. Those specific magnitudes
most plausibly trace to per-disease hazard ratios in the Levine 2023 (Neuron)
biobank study, but they appear in that paper's figures/tables and could NOT be
verified from the abstract; they are therefore NOT asserted here as quantitative
signals. Only the verifiable qualitative abstract statements are curated. The
adjacent Sipila 2021 cohort quantifies an infection->dementia association but is
for ANY hospital-treated infection, not influenza specifically. Kept as CANDIDATE
pending extraction of the influenza-specific HRs from full text.
disease_a:
slug: Influenza
disease_b:
slug: Alzheimer_Disease
directionality: A_BEFORE_B
literature_evidence:
- reference: PMID:36669485
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Influenza with pneumonia was significantly associated with five of the six neurodegenerative diseases studied."
explanation: >-
Cross-biobank study reports that influenza with pneumonia is significantly
associated with multiple neurodegenerative diseases (the numeric per-disease
hazard ratios are in the source tables, not the abstract).
- reference: PMID:34166620
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "Hospitalisation for any infectious disease was associated with increased dementia risk in the primary cohort"
explanation: >-
Adjacent cohort evidence that hospital-treated infection is associated with
increased dementia risk; not influenza-specific, so only partial support for
the influenza->Alzheimer's trajectory.
hypotheses:
- description: >-
Severe influenza (especially with pneumonia) may contribute to later
neurodegeneration through systemic and neuroinflammation, cerebrovascular
injury, and accelerated amyloid/tau pathology; an alternative/competing
explanation is reverse causation or shared frailty/susceptibility, and the
influenza-specific effect size on Alzheimer's disease is not yet verified
here from primary full text.
evidence:
- reference: PMID:36669485
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "we identified 45 viral exposures significantly associated with increased risk of neurodegenerative disease and replicated 22 of these associations."
explanation: >-
Supports a broader pattern of viral exposures associated with later
neurodegenerative disease, of which influenza-with-pneumonia is one.