Since the Asp23-Lys28 salt bridge appears to be important for AIP to inhibit Aβ42-mediated toxicity, we tested the Aβ42 D23N Iowa mutation peptide which is associated with progressive AD-like dementia, and has been found to be more neurotoxic and to aggregate more rapidly than the wt peptide40. The gene discussed is AIP; the disease is Alzheimer disease.