Provided herein are methods of reducing and/or inhibiting A deposition or A plaque formation in the brain, and/or inhibiting or slowing the progression of disorders mediated by A deposition or A plaque formation using therapeutically effective amounts of amylin agonist compounds or pharmaceutical compositions comprising amylin agonist compounds. As demonstrated herein, amylin and amylin analog administration improves cognition, including memory. Also provided herein are non-invasive, inexpensive amylin or amylin analog challenge assays and methods and kits thereof for detecting the presence of plaques comprising A? peptide in the brain, and for identifying individuals at increased risk for Alzheimers disease (AD) and/or amnestic mild cognitive impairment.