Classification of occupations

The current version of the international standard classification of occupations (ISCO-08) was used for formal categorization. Based on the amount of motor demands in previous careers, we classified individuals into either lower physically complex occupations (LPCO) or higher physically complex occupations (HPCO). The LPCO group included occupations that require interaction with people and data (including group 01: managers, 02: professionals, and 03: science and associate professionals), office, sales and care professionals (including group 04: clerical support workers, subgroup 05.2: sales workers, and 05.3: care professionals). The HPCO group comprised service workers (subgroup 05.1) and other physically challenging jobs (including group 06: skilled agricultural, forestry and fisher workers, group 07: craft and related trades workers, 08: plant and machine operators and assemblers, and 09: elementary occupations), and armed forces. We further calculated the time since retirement defined as the time period between scan date and year of retirement. Lifetime education was defined as the number of years of formal education successfully attended over a person’s lifetime and inquired during the personal interview.