Stephan Winkler is going to present the paper Heuristic Modeling of the Mental Progress of Persons with Normal Brain Aging, Subjective Cognitive Impairment, Mild Cognitive Impairment, Alzheimer's Disease and Related Dementia Disorders at the 21st European Modeling und Simulation Symposium (EMSS 2009). The work presented is a joint contribution between Stephan Winkler and Michael Affenzeller from the Upper Austria University of Applied Sciences, Hagenberg, Austria, Stefanie Auer and Yvonne Donabauer from the M·A·S Alzheimerhilfe, Bad Ischl, Austria and Barry Reisberg from the Department of Psychiatry of the New York University Langone Medical Center, NY, USA.