Provided are methods of inhibiting aggregation of amyloid-beta (Aβ) or accumulation of aggregated Aβ using certain guanylhydrazone compounds. Also provided are methods of treating or preventing an amyloid-related disease in a mammal, methods of treating a subject having Alzheimers disease, methods of treating a subject at risk for Alzheimers disease, methods of inhibiting aggregation or accumulation of a synuclein, methods of treating a subject having a disease at least partially mediated by synuclein, methods of treating a subject at risk for a disease at least partially mediated by synuclein, and methods of inhibiting aggregation or accumulation of a protein involved in a conformational disease, using the guanylhydrazone compounds.
