Abstract: The present invention relates to screening assays for functional analogues and antagonists of a polypeptide fragment of acetylcholinesterase (AChE), which is believed to exhibit activity corresponding to non-enzymatic function of AchE in the brain. These assays stem from linkage of such non-enzymatic activity with a target site on the homomeric alpha 7 nicotinic receptor. Antagonists thus identified which are capable of formulation for passage through the blood-brain barrier may be advantageous therapeutic agents for the treatment of a number of neurodegenerative diseases, in particular Alzheimer's Disease, Parkinson's Disease and Motor Neuron Disease.