Bergdahl E, Gustaysson JM, Kallin K, von Heideken Wågert P, et al.: Depression among the oldest old ; The Umeå, 85+ study. Int Psychogeriatr, 17 (4) : 557-575 (2005).
Bullain SS, Corrada MM, Perry SM, Kawas CH : Sound body sound mind? Physical performance and the risk of dementia in the oldest-old ; The 90+ study. J Am Geriatr Soc, 64 (7) : 1408-1415 (2016).
Corrada MM, Brookmeyer R, Berlau D, Paganini-Hill A, et al.: Prevalence of dementia after age 90 ; Results from the 90+ study. Neurology, 71 (5) : 337-343 (2008).