Table 7.
Summary of factors related to age that impact HT and BBB.
| Marker | Effect on BBB/consequences/contribution to risk of HT | References (for further reading) |
|---|---|---|
| Changes to the immune system and response | ||
| Inflammation: low grade chronic inflammation. Elevated levels of proinflammatory mediator's TNF, IL-1β, IL-6 | Effect the inflammatory response and BBB permeability/ function | (110–112) |
| Increase in PAI-1 | Interferes with the tPa/alteplase degradation | (113) |
| Decrease in VEGF and IGF-1 | Alter the angiogenesis response | (114) |
| Changes to the inflammatory response | ||
| Enhanced neutrophil response/recruitment | Increased MMP-9 and ROS | (106) |
| Enhanced microglial response | Enhanced inflammation and BBB permeability | (115) |
| Mechanical cellular changes due to aging | ||
| Endothelial cells change in structure and adopt a senescence phenotype | Increased ROS which reduces NO activity | (116) |
| Decrease in pericytes | Mechanical disruption to BBB permeability | (105) |
| Astrocytes change structure | Mechanical disruption to BBB permeability | (105, 115) |
BBB, Blood brain barrier; IGF-1, insulin-like growth factor 1; IL, interleukin; NO, nitric oxide; PAI-1, plasminogen activator inhibitor-1; TNF, tumor necrosis factor; tPa, tissue plasminogen activator; VEGF, vascular endothelial growth factor.