The content of the questionnaires was a balance between retention of items used in the earlier questionnaires in order to get 2,3 or 4 measures over time and a need to assess age-specific outcomes of interest, such as intentions to retire. Despite the development of better measures for some topics, we retained the original questions (such as used in 1975 and 1981) wherever possible. A total of 241 items were included in the questionnaires, covering domains such as twin pair relationships, general health and risk factor measurements (blood pressure, diabetes, cholesterol), standard symptoms (chronic bronchitis, dyspnea), musculoskeletal pain, bruxism, history of common diseases and use of various medications including hormone replacement therapy for women. We asked six questions on sleep and seven items on work and retirement. A detailed smoking history was taken again supplemented by nicotine dependence scales (Fagerström Test for Nicotine Dependence and the Wisconsin Inventory of Smoking Dependence Motives) and exposure to second-hand smoke over their lifetime. Quantity, frequency and problem measures of alcohol use and abuse were asked, including a screen for alcohol problems. Coffee and
