Common causes of dementia based on age at presentation and rate of progression. “Mixed” refers to combined Alzheimer disease and vascular dementia. Totals of <100% reflect absence of an etiologic diagnosis in some cases. (Data from Kelley BJ, Boeve BF, Josephs KA. Young-onset dementia: demographic and etiologic characteristics of 235 patients. Arch Neurol. 2008;65:1502-1508. Garre-Olmo J, Genís Batlle D, del Mar Fernández M, et al. Incidence and subtypes of early-onset dementia in a geographically defined general population. Neurology. 2010;75:1249-1255. Geschwind MD, Shu H, Haman A, Sejvar JJ, Miller BL. Rapidly progressive dementia. Ann Neurol. 2008;64:97-108.) Source: Dementia & Amnestic Disorders, Clinical Neurology, 10e Citation: Simon RP, Aminoff MJ, Greenberg DA. Clinical Neurology, 10e; 2017 Available at: http://neurology.mhmedical.com/DownloadImage.aspx?image=/data/books/2274/simon10_ch5_f002-1.png&sec=176232318&BookID=2274&ChapterSecID=176232284&imagename= Accessed: March 03, 2018 Copyright © 2018 McGraw-Hill Education. All rights reserved