AAIC 2026 — Neurovascular Function and Cerebral Blood Flow in Alzheimer's

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

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

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:

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

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:

The mechanisms underlying impaired neurovascular coupling include:

• Endothelial dysfunction and reduced nitric oxide bioavailability
• Pericyte contractile dysfunction
• Astrocytic endfeet damage
• Increased vascular stiffness with aging

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:

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

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

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

Emerging 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 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