NEFL and Dravet syndrome: In individuals with DS, changes in cerebrospinal fluid (CSF) amyloid beta (Aβ)42/40 ratio and plasma neurofilament light chain (NfL) levels typically begin around the age of 30, followed by alterations in amyloid positron emission tomography (PET) uptake and CSF phosphorylated tau (p‐tau) levels in subsequent years.8, 9, 10