Methods of inhibiting beta-amyloid-mediated activation of the p75 nerve growth factor receptor of a cell that expresses the p75 nerve growth factor receptor are provided. Methods of inhibiting the binding of beta-amyloid protein and beta-amyloid peptides to the p75 nerve growth factor receptor, and methods of inhibiting beta-amyloid-mediated apoptosis of neural crest-derived cells are provided. The methods comprise contacting the cell with a substance, comprising, for example, the amino acid sequence lysine-glycine-lysine (KGK) or lysine-glycine-alanine (KGA), wherein the substance binds to the p75 nerve growth factor receptor, resulting in the inhibition of beta-amyloid protein or beta-amyloid peptide binding to and/or activation of the p75 nerve growth factor receptor, or wherein the substance inhibits beta-amyloid protein or beta-amyloid peptide mediated apoptosis of the cell which expresses the p75 nerve growth factor receptor.
