[1] The ongoing study was established in 1963 by the United States Department of Veterans Affairs.
[2] The initial sample was 2,280 men now with an average age of 72 years (mean age at entry was 42 years).
[3] Participants in the study have undergone medical examinations every three to five years, also answering questions about behaviors affecting health.
[4] Among the topics researchers have used the NAS for are stress,[2] smoking, and cardiac health.
[5] One of the findings based on the study was that subjective stress appeared to be a better prediction of mortality than the objective evaluation of stressful events.