Lifetime principal occupation and risk of Alzheimer's disease in the Kungsholmen Project

Background Some studies suggest that manual work is associated with dementia. This study is aimed at identifying the specific occupational categories that may be related to dementia. Methods A cohort of 913 non-demented subjects aged 75+ years was longitudinally examined twice over 6 years to detect incident dementia using the DSM-III-R diagnostic criteria. The lifetime longest occupations of all subjects were divided into different categories according to the occupation-based classification system. Data were analyzed with Cox models. Results During the follow-up period, 260 subjects were diagnosed with dementia (197 with Alzheimer's disease). Manual work was associated with an increased risk of dementia, and the association was dependent on educational level. Compared with nonmanual work, manual work involving goods production had a multi-adjusted relative risk (95% CI) of 1.6 (1.0-2.5, P = 0.046) for Alzheimer's disease and 1.4 (0.9-2.1) for dementia. Conclusions An association between goods production, manual work and Alzheimer's disease found in this study suggests that factors in the mid-twentieth century goods production environment may be involved in the development of Alzheimer's disease. (C) 2003 Wiley-Liss, Inc.