Prognostic biomarkers for CI in synucleinopathies include brain regional atrophy (MRI findings), metabolic and cerebral blood flow changes (FDG-PET), cortical rhythm slowing, cerebrospinal fluid (CSF) amyloid (Aβ-40), Val66Met polymorphism, APOE ε4 and ε2 alleles [194], GFAP and neurofilament light chain (NfL) levels in CSF and plasma [195], the latter being significantly increased in all cortical neurodegenerative disorders including APs [8,196]. The gene discussed is APOE; the disease is synucleinopathy.