Cerebral small vessel disease alters neurovascular unit regulation of microcirculation integrity involved in vascular cognitive impairment

Cerebral small vessel disease (CSVD) is a generic term used for intracranial vascular disorders caused by the structural changes of cerebral microvessels, including the small arteries, arterioles, capillaries and venules. CSVD exhibits various neuroimaging features and is associated clinical characteristics. Although CSVD is recognized as the leading cause of vascular cognitive impairment (VCI), the underlying mechanism(s) remains elusive. Growing evidence indicates a significant association between altered neurovascular unit (NVU) functioning and the pathophysiology of evolving CSVD-induced VCI. Therefore, research is required to understand how NVU dysregulation contributes to cognitive impairment due to CSVD. In this review, we describe the link between the neuroimaging focal lesions and cognitive alterations. We also discuss the potential pathological role of NVU dysregulation in the entry of pathogens from the blood into the parenchyma by altering the blood-brain barrier (BBB), affecting the cerebral microvascular and consequently cause VCI. Next, we review the coupling of neural activity with cerebral blood flow to control the microvascular perfusion; and the disrupted clearance of metabolic byproducts with CSF-ISF exchange via perivascular pathways and glymphatic system. Finally, we discussed the possible therapeutic interventions in CSVD.