Cyclic D,L-α-peptides were shown to have an anti-amyloid aggregation effect. The cyclic peptide (designated cyclic peptide-2) having the sequence [1JwHsK], had a drastic effect on amyloid aggregation. However, the linear equivalent of cyclic peptide-2 did not inhibit amyloid formation. Cyclic peptide 2 was also effective in reducing Aβ-induced toxicity in PC12 cells. According to embodiments of the invention, cyclic peptides may comprise between 6 or 8 amino acids. In an embodiment, half of the amino acid residues are in the D-formation, and the other half are in the L-formation. In an embodiment of the invention, the amino acids alternate between the D and L-formations.
