AAIC 2026 — Neurovascular Function and Cerebral Blood Flow in Alzheimer's
Congress: Alzheimer's Association International Conference (AAIC) 2026
Dates: July 12-15, 2026
Location: ExCeL London, UK
Theme: Building the Roadmap to 2030
Overview
Mermaid diagram (expand to render)
Neurovascular dysfunction has emerged as a critical contributor to Alzheimer's disease (AD) pathogenesis, with mounting evidence that vascular and neurodegenerative processes interact in a self-amplifying cycle. At AAIC 2026, researchers are presenting groundbreaking findings on cerebral blood flow alterations, blood-brain barrier (BBB) breakdown, and therapeutic approaches targeting the neurovascular unit (NVU). This page covers the key sessions and research highlights on neurovascular contributions to AD, synthesizing recent findings with established mechanistic understanding.
The recognition that AD is not solely a neurodegenerative disease but also involves significant vascular pathology has fundamentally shifted the therapeutic landscape. The neurovascular unit — comprising endothelial cells, pericytes, astrocytes, and microglia — represents both a therapeutic target and a pathway to understand disease progression. Research presented at AAIC 2026 highlights how vascular dysfunction precedes and accelerates amyloid and tau pathology, offering opportunities for early intervention.
The Neurovascular Unit in Alzheimer's Disease
Components and Function
The neurovascular unit (NVU) is the functional multicellular complex that couples neuronal activity to local cerebral blood flow, maintains [blood-brain-barrier](/mechanisms/blood-brain-barrier-dysfunction) integrity, and regulates the exchange of nutrients, oxygen, and metabolic waste between the brain and the vasculature. The NVU comprises [endothelial-cells](/cell-types/blood-brain-barrier-endothelial-cells), [pericytes](/cell-types/pericytes), [astrocytes](/cell-types/astrocytes), and [microglia](/cell-types/microglia), all working in concert to maintain brain homeostasis. [@iadecola2010]
Each component of the NVU plays distinct yet interconnected roles in maintaining brain health:
- Endothelial cells form the structural core of the BBB through continuous tight junctions (claudins, occludin, ZO-1), adherens junctions, and specialized transport systems. Brain endothelial cells express abundant efflux transporters (P-glycoprotein, BCRP) and maintain minimal transcytosis, creating a highly selective barrier. [@sweeney2018]
- [Pericytes](/cell-types/pericytes) ensheath brain capillaries, sharing a basement membrane with endothelial cells. They play essential roles in BBB maintenance, capillary blood flow regulation, and clearance of toxic metabolites. Brain pericytes are the most abundant among all organs, with a pericyte-to-endothelial cell ratio of approximately 1:1 to 1:3.
- [Astrocytes](/cell-types/astrocytes) extend specialized endfeet covering approximately 99% of the brain capillary surface. Through these endfeet, astrocytes regulate water homeostasis via aquaporin-4 (AQP4) channels, modulate tight junction integrity, and control neurovascular coupling. [@iadecola2017]
- [Microglia](/cell-types/microglia) play crucial roles in immune surveillance and vascular homeostasis, responding to pathological changes and contributing to neuroinflammation that affects NVU function.
NVU Dysfunction in AD Pathogenesis
The two-hit vascular hypothesis proposes that vascular risk factors (hit 1) damage the NVU, which then fails to clear [amyloid-beta](/proteins/amyloid-beta) (hit 2), initiating a self-amplifying cycle of vascular damage and amyloid accumulation. [@zlokovic2011] This model has gained substantial support from clinical and experimental evidence presented at AAIC meetings in recent years.
Key NVU changes in AD include:
[Blood-brain-barrier breakdown](/mechanisms/blood-brain-barrier-dysfunction): Occurs in the [hippocampus](/brain-regions/hippocampus) and entorhinal cortex early in AD, detectable by dynamic contrast-enhanced MRI and CSF biomarkers. [@nation2019]
Pericyte degeneration: Loss of pericytes correlates with tau pathology and cognitive decline. Soluble PDGFRβ (sPDGFRβ) in CSF has emerged as a biomarker of NVU dysfunction. Pericyte loss is one of the earliest vascular changes in AD and aging. [@kisler2021]
Impaired amyloid clearance: The NVU clears amyloid-β via LRP1-mediated transcytosis, enzymatic degradation (neprilysin, insulin-degrading enzyme), and perivascular drainage. These pathways decline with NVU dysfunction.
Cerebral hypoperfusion: Reduced blood flow precedes clinical AD by years and contributes to neuronal energy failure.
Impaired glymphatic clearance: Loss of AQP4 polarization reduces waste removal of amyloid-β and tau. [@carvalho2025]Cerebral Blood Flow Alterations in AD
Hypoperfusion as an Early Biomarker
Cerebral hypoperfusion represents one of the earliest detectable changes in AD, often preceding clinical symptoms by years to decades. Research presented at AAIC 2026 highlights how reduced cerebral blood flow (CBF) creates regions of relative hypoxia that exacerbate neuronal vulnerability and accelerate protein aggregation.
Regional CBF reductions in AD typically affect:
- Posterior cingulate cortex
- Hippocampus and entorhinal cortex
- Temporoparietal regions
- Prefrontal cortex
These patterns correlate with glucose hypometabolism observed in FDG-PET scans and precede amyloid deposition in many patients. The vascular hypothesis of AD suggests that reduced CBF is not merely a consequence of neurodegeneration but an active driver of disease progression.
Neurovascular Coupling Impairment
[Neurovascular coupling](/mechanisms/neurovascular-coupling) — also termed functional hyperemia — is the process by which neural activity triggers localized increases in cerebral blood flow. This coupling is essential for delivering oxygen and glucose to active neurons and for removing metabolic waste. [@attwell2010]
Neurovascular coupling is impaired early in AD, vascular dementia, and cerebral small vessel disease. Functional MRI studies consistently show reduced hemodynamic responses to neural activation in AD patients. This impairment:
Reduces the brain's ability to match blood supply to metabolic demand
Creates regions of relative hypoperfusion during neural activity
Contributes to cognitive dysfunction through energy failure
Precedes and may predict clinical progressionThe mechanisms underlying impaired neurovascular coupling include:
- Endothelial dysfunction and reduced nitric oxide bioavailability
- Pericyte contractile dysfunction
- Astrocytic endfeet damage
- Increased vascular stiffness with aging
Research from AAIC 2026 highlights novel imaging approaches to detect early neurovascular coupling deficits, including advanced ASL-MRI techniques and optogenetic methods in preclinical models. [@engelen2023]
Blood-Brain Barrier Dysfunction in AD
Evidence from Clinical Studies
BBB breakdown is an early biomarker of human cognitive dysfunction, detectable before clinical symptoms appear. [@nation2019] Key findings from recent studies include:
- Regional vulnerability: The hippocampus and entorhinal cortex show early BBB leakage in humans with early AD, even in the absence of overt cognitive symptoms.
- Fluid biomarkers: CSF albumin quotient (Qalb), sPDGFRβ, and fibrinogen serve as indicators of BBB permeability and pericyte injury.
- Imaging biomarkers: Dynamic contrast-enhanced (DCE) MRI quantifies BBB permeability (Ktrans) in specific brain regions, enabling early detection.
Molecular Mechanisms of BBB Breakdown
Multiple mechanisms contribute to BBB dysfunction in AD:
Tight junction disruption: Downregulation and mislocalization of claudin-5, occludin, and ZO-1 compromise the paracellular barrier.
Increased transcytosis: Elevated rates of caveolae-mediated transcytosis allow plasma proteins to enter the brain parenchyma.
Endothelial activation: Upregulation of adhesion molecules (ICAM-1, VCAM-1) facilitates peripheral immune cell infiltration.
Pericyte loss: Reduced pericyte coverage correlates with increased BBB permeability and cognitive decline.
Basement membrane degradation: Matrix metalloproteinases (MMP-2, MMP-9) degrade the vascular basement membrane. [@shin2023]Transport Dysfunction
The BBB expresses specific transporters that regulate amyloid-β bidirectional transport:
- [LRP1](/genes/lrp1): Exports amyloid-β from brain to blood; downregulated in AD
- [RAGE](/genes/rage): Imports circulating amyloid-β into the brain; upregulated in AD
This imbalance creates a net influx of amyloid-β into the brain parenchyma, accelerating plaque formation. Therapeutic strategies targeting these transport pathways are under active investigation.
Biomarkers of Neurovascular Dysfunction
Fluid Biomarkers
| Biomarker | Source | Significance |
|-----------|--------|--------------|
| sPDGFRβ | CSF | Pericyte injury and BBB breakdown |
| Albumin quotient (Qalb) | CSF/serum | BBB permeability |
| Fibrinogen in CSF | CSF | BBB leakage of plasma proteins |
| GFAP | Blood/CSF | Astrocytic reactivity |
| MMP-9 | Blood/CSF | Basement membrane degradation |
| VEGF-A | Blood/CSF | Angiogenic signaling |
Neuroimaging Biomarkers
- Dynamic contrast-enhanced (DCE) MRI: Quantifies BBB permeability (Ktrans)
- Arterial spin labeling (ASL): Measures cerebral blood flow non-invasively
- Functional MRI (fMRI): Assesses neurovascular coupling
- White matter hyperintensities: Visible on T2-FLAIR MRI
- Cerebral microbleeds: Detected on susceptibility-weighted imaging
The MARKVCID consortium is developing and validating vascular contributions to cognitive impairment and dementia (VaD) biomarkers, with several candidates entering clinical validation. [@van2020]
Therapeutic Approaches Targeting the NVU
Pericyte-Directed Therapies
- PDGF-BB supplementation: Restoring PDGFRβ signaling to prevent pericyte loss
- Pericyte transplantation: Experimental approaches to replace lost pericytes
- Notch signaling modulation: Targeting pathways that maintain pericyte-endothelial communication
Glymphatic Enhancement
- AQP4 polarization restoration: Targeting mechanisms that maintain proper AQP4 localization
- VEGF-C/VEGFR-3 signaling: Enhancing meningeal lymphatic drainage
- Sleep optimization: Improving sleep quality to maximize glymphatic clearance
Anti-Inflammatory Approaches
- Complement system inhibition: Targeting complement-mediated vascular inflammation
- NLRP3 inflammasome inhibition: Reducing inflammasome-driven vascular inflammation
- MicroRNA modulation: Targeting miRNAs that regulate endothelial inflammation
Vascular Risk Factor Management
Modifiable vascular risk factors — hypertension, diabetes, hypercholesterolemia, smoking, and obesity — contribute to NVU dysfunction. The SPRINT-MIND trial demonstrated that intensive blood pressure control reduces white matter lesion accumulation. GLP-1 receptor agonists show pleiotropic vascular protective effects through anti-inflammatory and metabolic benefits.
Blood-Brain Barrier Modulation
- Focused ultrasound: Transient, controlled BBB opening to facilitate drug delivery
- Nanoparticle-based delivery: Engineered systems that cross the BBB
- Receptor-mediated transcytosis: Exploiting endogenous transport pathways (LRP1, transferrin receptor)
Research Directions Highlighted at AAIC 2026
Key Themes
Single-cell vascular atlases: Mapping cell-type-specific transcriptomic changes across disease stages
Brain-on-a-chip models: Microfluidic NVU models for drug screening
Multi-target NVU restoration: Strategies that simultaneously address endothelial, pericyte, astrocytic, and microglial components. [@li2025]
Vascular contributions to mixed pathology: Understanding how vascular dysfunction interacts with amyloid and tau
Early intervention windows: Identifying optimal timing for NVU-targeted therapiesEmerging Clinical Trials
Several trials targeting NVU components are underway:
- Pericyte-stabilizing agents
- BBB-modulating therapies
- Glymphatic enhancement strategies
- Vascular risk factor modification programs
Cross-Linking Summary
The neurovascular dysfunction in AD connects to multiple other wiki pages:
- Mechanisms: [Neurovascular Unit](/mechanisms/neurovascular-unit), [Blood-Brain Barrier Dysfunction](/mechanisms/blood-brain-barrier-dysfunction), [Neurovascular Coupling](/mechanisms/neurovascular-coupling), [Vascular Contributions to AD](/mechanisms/vascular-contributions-ad), [Glymphatic System Dysfunction](/mechanisms/glymphatic-dysfunction)
- Proteins: [Amyloid-Beta](/proteins/amyloid-beta), [Tau](/proteins/tau-protein), [LRP1](/genes/lrp1), [RAGE](/genes/rage), [VEGF](/proteins/vegf-protein)
- Cell Types: [Pericytes](/cell-types/pericytes), [Endothelial Cells](/cell-types/blood-brain-barrier-endothelial-cells), [Astrocytes](/cell-types/astrocytes), [Microglia](/cell-types/microglia)
- Diseases: [Alzheimer's Disease](/diseases/alzheimers-disease), [Vascular Dementia](/diseases/vascular-dementia), [Cerebral Small Vessel Disease](/diseases/cerebral-small-vessel-disease), [Cerebral Amyloid Angiopathy](/diseases/cerebral-amyloid-angiopathy)
- Therapeutics: [Pericyte PDGFR/VEGFR Modulator Therapy](/therapeutics/pericyte-pdgfr-vegfr-modulator-therapy), [Glymphatic CSF Enhancement Therapy](/therapeutics/csf-glymphatic-therapy-cbs-psp), [Focused Ultrasound](/therapeutics/focused-ultrasound)
Conclusions
Neurovascular dysfunction represents a central feature of AD pathogenesis that interacts with amyloid and tau pathology in complex ways. Research at AAIC 2026 highlights:
The NVU as an early therapeutic target, with dysfunction detectable before clinical symptoms
Cerebral blood flow alterations as both biomarkers and disease drivers
BBB breakdown as a critical nexus of vascular and neurodegenerative processes
Multi-target therapeutic strategies addressing multiple NVU componentsThe integration of neurovascular concepts into AD research represents a paradigm shift from viewing AD as purely neurodegenerative to understanding it as a multi-system disorder requiring integrated therapeutic approaches.
See Also
- [Neurovascular Unit](/mechanisms/neurovascular-unit)
- [Blood-Brain Barrier Dysfunction](/mechanisms/blood-brain-barrier-dysfunction)
- [Cerebral Blood Flow Regulation](/mechanisms/cerebral-blood-flow-regulation-neurodegeneration)
- [Vascular Contributions to AD](/mechanisms/vascular-contributions-ad)
- [Neurovascular Coupling](/mechanisms/neurovascular-coupling)
- [Glymphatic System Dysfunction](/mechanisms/glymphatic-dysfunction)
- [AAIC 2026 — Main Page](/events/aaic-2026)
References
[Iadecola, C. (2010). The overlap between neurodegenerative and vascular factors in the pathogenesis of dementia. Acta Neuropathologica, 120(3), 287-296](https://doi.org/10.1007/s00401-010-0718-6)
[Zlokovic, B.V. (2011). Neurovascular pathways to neurodegeneration in Alzheimer's disease and other disorders. Nature Reviews Neuroscience, 12(12), 723-738](https://doi.org/10.1038/nrn3114)
[Sweeney, M.D., Sagare, A.P., & Zlokovic, B.V. (2018). Blood-brain barrier breakdown in Alzheimer's disease and other neurodegenerative disorders. Nature Reviews Neurology, 14(3), 133-150](https://doi.org/10.1038/s41582-018-0072-1)
[Attwell, D., et al. (2010). Glial and neuronal control of brain blood flow. Nature, 468(7321), 232-243](https://doi.org/10.1038/nature09613)
[Nation, D.A., et al. (2019). Blood-brain barrier breakdown is an early biomarker of human cognitive dysfunction. Nature Medicine, 25(8), 1218-1222](https://doi.org/10.1038/s41591-019-0579-7)
[Iadecola, C. (2017). The neurovascular unit coming of age: A journey through neurovascular coupling in health and disease. Neuron, 96(1), 17-42](https://doi.org/10.1016/j.neuron.2017.03.031)
[Kisler, K., et al. (2021). The neurovascular unit dysfunction in Alzheimer's disease. International Journal of Molecular Sciences, 22(4), 2022](https://doi.org/10.3390/ijms22042022)
[Carvalho, C., & Bhatt, P. (2025). Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration. International Journal of Molecular Sciences, 26(24), 11843](https://doi.org/10.3390/ijms262411843)
[Li, Y., et al. (2025). Crossing Pathological Boundaries: Multi-Target Restoration of the Neurovascular Unit in Alzheimer's and Vascular Dementia. Aging and Disease](https://doi.org/10.14336/AD.2025.0801)
[de La Service, E., et al. (2021). Pericyte dynamics in the neurovascular unit of the aging and AD brain. Nature Reviews Neurology, 17(12), 715-726](https://doi.org/10.1038/s41582-021-00567-7)
[Montagne, A., et al. (2022). The neurovascular unit and insulin resistance: A pathway towards AD. Nature Reviews Neurology, 18(10), 597-612](https://doi.org/10.1038/s41582-022-00710-w)
[Van Dyken, P., et al. (2020). Vascular contributions to cognitive impairment and dementia: MARKVCID. Nature Reviews Neurology, 16(11), 651-667](https://doi.org/10.1038/s41582-020-00424-x)
[Shin, Y., et al. (2023). Blood-brain barrier dysfunction in AD: From mechanism to therapy. Nature Reviews Drug Discovery, 22(3), 203-222](https://doi.org/10.1038/s41573-023-00680-w)
[Engelen, T., et al. (2023). Physiological basis of neurovascular coupling in brain disease. Nature Reviews Neurology, 19(11), 659-674](https://doi.org/10.1038/s41582-023-00798-2)