Cerebral small vessel disease (CSVD) is a core etiology of vascular cognitive impairment (VCI), accounting for over 40% of covert stroke-related cognitive decline. Recent studies have revealed that CSVD pathophysiology extends beyond traditional "ischemic-centric" theories, involving multidimensional interactions such as endothelial glycocalyx damage, neurovascular unit (NVU) decoupling, and glymphatic dysfunction. This review systematically summarizes molecular mechanisms, multimodal imaging biomarkers, clinical heterogeneity, and precision intervention strategies for CSVD, integrating recent evidence to guide clinical practice.

Cerebral small vessel disease (CSVD) refers to pathologies affecting penetrating arterioles, venules, and capillaries (<500 ?m), with imaging markers (white matter hyper intensities, lacunas, micro bleeds) detected in 95% of individuals over 60 [1]. The 2022 STRIVE-2 consensus classified cognitive impairment as a core clinical phenotype of CSVD [2].  Advanced imaging techniques (7T MRI and tau-PET) have uncovered synergistic pathological effects between CSVD and Alzheimer's disease (AD) [3]. CSVD accounts for 15%-20% of dementia cases and frequently coexists with AD pathology (dual pathology hypothesis) [4]. Emerging evidence shows that early CSVD disrupts default mode network (DMN) connectivity and white matter tracts, impairing information processing speed (IPS) and executive function (EF), often underestimated by conventional MRI [5].

Vascular endothelial dysfunction

Endothelial injury is central to CSVD pathogenesis, Genetic mutations, COL4A1/2 mutations cause abnormal type IV collagen ?-chains, leading to basement membrane thickening and micro aneurysms [6]; NOTCH3 mutations (CADASIL) induce vascular smooth muscle cell degeneration and impaired cerebral autoregulation [7]. 

Oxidative stress

Mitochondrial ROS overproduction activates NLRP3 inflammasomes, promoting IL-1? release [8]. Hemodynamic instability: Altered endothelial shear stress from cerebral blood flow fluctuations (reduced BOLD-fMRI low-frequency amplitude) triggers ET-1 imbalance [9].

Blood-Brain Barrier (BBB) Disruption

BBB leakage is a key node in the transformation of CSVD to cognitive impairment [10]

Molecular mechanisms

Downregulation of tight junction proteins (Claudin-5, Occludin) and MMP-9 activation enlarge perivascular spaces (PVS) [11]. Loss of AQP4 polarity in astrocytic end feet impedes perivascular ?-amyloid clearance [12]. 

Imaging evidence

DCE-MRI shows dose-dependent correlation between BBB leakage (Ktrans) and white matter hyper intensity (WMH) volume, predominantly in deep watershed zones [13]. 

Neuroinflammation and Microglial Activation

CSVD induces neuroinflammation via a "two-hit" model [14]. Hypoxia polarizes microglia to pro-inflammatory (M1) phenotype, releasing TNF-?, IL-6, and ROS [15]. Complement C1q-C3 cascade mediates excessive synaptic pruning, reducing hippocampal CA1 dendritic spine density by 40% [16]. CSF sTREM2 (microglial marker) correlates with WMH progression rate [17-21]. 

Imaging Biomarkers and Clinical Phenotypes

Clinical Subtypes and Cognitive Features

· Executive Dysfunction (62%) 

Core lesion: Dorsolateral prefrontal cortex (DLPFC)-caudate circuit [22] (Table 1)

Neuropsychology: Stroop interference time >45s, Digit Symbol Substitution Test (DSST) <35 [23] 

Imaging: Frontal WMH >5cm³, reduced genu FA [24] 

Core lesion: Parahippocampal white matter tract, fornix-mamillary pathway [25] 

Neuropsychology: RAVLT delayed recall <4 words, ADAS-Cog memory score >8 [26] 

Imaging: Elevated MD in inferior longitudinal fasciculus, entorhinal tau-PET uptake [27] 

·Mixed Type (15%) 

Pathology: CSVD+AD dual pathology (A?-PET+, WMH >10cm³) [28] 

Prognosis: 3.2-fold higher dementia conversion risk vs pure CSVD [29]  

Risk Factor Management 

Blood pressure control: SPRINT-MIND showed intensive control (SBP <120 mmHg) reduces WMH progression by 40% [30].  ACEI/ARB drugs can specifically improve BBB integrity [31]. Glycemic control: Hyperglycemia damages endothelial glycocalyx via AGEs; diabetics have 32% larger WMH [32]. SGLT-2 inhibitors (empagliflozin) reduce WMH progression [33-36] (Table 2).

 Table 2: Targeted Pharmacotherapy.

Non-Pharmacological Interventions 

Aerobic training (150 min/week) increases hippocampal volume by 2.3% and executive function by 14% [37]. Arm cuff training (5 min/session, bid) activates HIF-1?, reducing plasma NfL by 18% [38].    

Accurate typing, based on multi omics (genome+proteome+metabolome), can construct CSVD subtype prediction models (such as endothelial type, inflammatory type) [39]. New imaging technologies such as 7T MRI can visualize cortical micro infarcts (<1 mm lesions) [40], and magnetic sensitive quantitative imaging (QSM) can quantify the relationship between brain iron deposition and cognitive decline [41]. Targeted drug delivery systems such as liposome encapsulated siRNA can effectively inhibit the expression of MMP-9 in endothelial cells [42], while magnetic nanoparticles loaded with VEGF can promote angiogenesis [43].

This work was supported by Medical Science Research Program of Hebei Health Commission (No. 20221417).

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