Fig. 5

Prior health conditions effects on the BBB. Obesity is linked to increase in inflammatory cytokines which can lead to activation of astrocytes and microglia and death of neuronal cells, leading to wide spread neuro-inflammation, tight junction breakdown and damage to the CNS. Diabetes and hyperglycaemia cause pathological changes to the BBB, including increased capillary density, thickening of the basement membrane, breakdown of tight junctions and increase in paracellular diffusion. Pericytes are also shown to degenerate and aid in the decrease in barrier properties. Hypertension is linked to the RAS system and Ang-11 levels, increase in inflammatory cytokines and Reactive oxygen species (ROS) damage to endothelial cells and activation of microglia and astrocytes. Age has widespread effects on the BBB, decrease in barrier functions, decrease in efflux pumps and impaired energy utilization. There is also increased movement across the BBB by increase in paracellular movement, increase in pinocytosis leading to astrocytes and microglia activation