GFAP and Cognitive impairment: One study showed that plasma GFAP levels were higher in PD patients with dementia compared with PD patients without cognitive impairment or healthy controls (HCs) [11], whereas another study reported that 11C-BU99008, an imidazoline-2 binding site-specific positron emission tomography (PET) radioligand which can image reactive astrocytes in vivo, cannot differentiate patients with Parkinson’s disease dementia from HCs of similar age [12].