The invention relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of impaired synaptic plasticity. The invention also relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of toxicity of Aβ oligomers. The invention also relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of Alzheimer's Disease. The invention also relates to methods of medical treatment.
