REPORT FROM THE 2009 AAN ANNUAL MEETING – Several recent studies have indicated that cortical thickness measures may be a useful MRI marker to distinguish mild cognitive impairment (MCI) from normal aging (Wang et al. AJNR Am J Neuroradiol 2009; epublished March 11, 2009), identify patients at risk of developing Alzheimer’s disease (Bakkour et al. Neurology 2009;72:1048-1055), and to differentiate Alzheimer’s disease from frontotemporal dementia (Du et al. Brain 2007;130(pt 4):1159-1166; free download at http://brain.oxfordjournals.org/cgi/content/full/130/4/1159).