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AlzRisk Cohort Detail

Cohort: Adult Health Study of the Radiation Effects Research Foundation
Risk Factors:

Introduction to the Cohort
The Atomic Bomb Casualty Commission, which later became the Radiation Effects Research Foundation (RERF), established the Adult Health Study (AHS) in 1958 in order to investigate the effects of radiation on various health outcomes and to better understand the physiologic changes that occur as a result of exposure to radiation. The AHS is actually a subcohort of a larger study, the Life Span Study (LSS), which is also administered by the RERF. Approximately 20,000 participants were recruited for participation in the AHS in 1958. These original participants included residents of Hiroshima and Nagasaki, Japan according to the 1950 census and the Atomic Bomb Survivors Survey. Approximately half of these participants were within 2000 m of the hypocenter at the time of the atomic blast, approximately 25% more than 3000 m away from the hypocenter, and approximately 25% absent from the city. Additional participants were added in 1977 to expand the size of the cohort (~2,400) and to add a sample of participants who were exposed to radiation in utero (~1,000). All members of the AHS are invited to participate in biennial examinations, including a physical examination, routine laboratory tests, and assessment of medical history and lifestyle.

In 1992, the AHS began screening for dementia among participants ages 60 and older who resided in Hiroshima. Of those with full risk factor information who were screened between 1992 and 1997, 73.2% were women.

Ethnicity Breakdown
All participants were residents of Hiroshima or Nagasaki. Presumably, the vast majority are Japanese.

Diagnosis & Evaluation Methods
AHS participants who reside in Hiroshima and who were aged 60 and older were screened for dementia beginning in 1992. As of 1997, 84.5% of eligible participants agreed to participate (2,463 participants). For a detailed description of screening and dementia diagnosis protocols, see Yamada et al. (1999).

Yamada M, Sasaki H, Mimori Y, Kasagi F, Sudoh S, Ikeda J, et al. Prevalence and risks of dementia in the Japanese population: RERF's adult health study Hiroshima subjects. Radiation Effects Research Foundation. J Am Geriatr Soc. 1999 Feb;47(2):189-195.

Yamada M, Kasagi F, Sasaki H, Masunari N, Mimori Y, Suzuki G. Association between dementia and midlife risk factors: the Radiation Effects Research Foundation Adult Health Study. J Am Geriatr Soc. 2003 Mar;51(3):410-414.

Wong FL, Yamada M, Sasaki H, Kodama K, Akiba S, Shimaoka K, et al. Noncancer disease incidence in the atomic bomb survivors: 1958-1986. Radiat Res. 1993 Sep;135(3):418-430.

Radiation Effects Research Foundation. Adult Health Study (AHS), available at Accessed Aug 28, 2009.