The alpha-secretase activity discourages its accumulation. Recently, a link between cholinergic neuronal activity and the activity of alpha-secretase has been highlighted,[15] which can discourage Amyloid-beta proteins deposition in brain of patients with Alzheimer's Disease. Alzheimer's disease has been identified as a protein misfolding disease, or proteopathy, due to the accumulation of abnormally folded Amyloid-beta proteins in the brains of AD patients.[2] Abnormal amyloid-beta accumulation can first be detected using cerebrospinal fluid analysis and later using positron emission tomography (PET).[16]