Another proposed mechanism is that GFAP may diffuse from the cytosol of injured astrocytes across the blood–brain barrier which is altered and can become ‘leaky’ or damaged in the context of many types of dementia (Hussain et al., 2021), traumatic brain injury (Plog et al., 2015) and stroke (Dvorak et al., 2009). Here, GFAP is linked to brain injury.