Association between the psychosocial network and dementia—a case–control study
Introduction
An inverse association between dementia and previous education has been reported in several studies (Stern et al., 1992, Bickel and Cooper, 1994, Evans et al., 1997, Schmand et al., 1997, De Ronchi et al., 1998), although some other studies did not find this association (Paykel et al., 1994, Cobb et al., 1995, Munoz et al., 2000). One plausible hypothesis for low education as a risk factor is that poorly educated individuals have a reduced brain reserve (Erkinjuntti, 1988, Fratiglioni et al., 1991), probably due to a lesser synaptic reserve (Katzman, 1993). However, the apparent effect of education might at least partly be explained by its association with socioeconomic status (Del Ser et al., 1999, Munoz et al., 2000). Socioeconomic status is a major determinant of the choose of occupation (with consequent exposure, for example, to chemical toxins), habits such as smoking and alcohol consumption and leisure time activities such as sports and cultural activities. Therefore, education could possibly reflect other psychosocial risk factors rather than itself constitute a real etiological factor.
Psychosocial network is one of those “other” potential risk factors that recent epidemiological research has focussed on. A positive association has been observed between dementia and living alone (Fratiglioni et al., 2000), having no close social ties (Fratiglioni et al., 2000), not participating in social and leisure activities (Fabrigoule et al., 1995, Scarmeas et al., 2001), and never having married (Helmer et al., 1999). Recent studies have found that Alzheimer's disease in particular is negatively associated with diversity of activities (Friedland et al., 2001) and intensity of intellectual activities (Friedland et al., 2001) and positively associated with psychosocial inactivity (Kondo et al., 1994), unproductive working style, living with a dominant spouse (Kropiunigg et al., 1999) and with physical inactivity (Kropiunigg et al., 1999, Kondo et al., 1994, Laurin et al., 2001).
To further elucidate the possible etiological relevance to dementia of the psychosocial network, we have conducted a case–control study. The psychosocial network was studied at age 30, at age 50, and at 10 years before data collection.
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Study population
Our study was performed in the city of Frankfurt-on-Main and in the neighboring cities of Darmstadt, Offenbach and Bad Homburg. Patients with dementia were recruited in 23 general practices. Participating physicians were asked to review in detail their clinical records in order to identify all demented patients 65 years of age or more within their clientele. The primary care physicians were explicitly requested to exclude depressive disorders. If available, the manually transcribed information
Results
The odds ratios for the association between the psychosocial network factors at different ages and dementia of any type are shown in Table 1. At all ages considered significantly lowered odds ratios were found for the number of confidants, as well as for performing sports activities. At age 30 and at 10 years before data collection, dementia patients participated in significantly fewer cultural activities. 10 years before data collection, dementia cases were significantly less frequently
Discussion
The results of this study indicate a potential protective effect of the psychosocial network on dementia. Multivariate analyses suggest an independent effect, especially of sports and cultural activities, and of the number of confidants.
Only 71.7% of the control population could be MMSE scored (60.4% of the population controls, 85.2% of the ambulatory controls). 60 of the 72 control subjects with missing MMS examination were investigated by an abbreviated form of the MMSE (excluding language
Acknowledgments
This work was supported by a grant from the Alzheimer Forschung Initiative (AFI). We would like to thank K. Amadori, P. Geller, J. Jochim, Dr. U. Albrecht, Dr. G. Amadori, Dr. E. Balluff, Dr. H. Bastian, Drs. G. and C. Czakanski, Dr. C. Damm, Dr. R. Deml, Dr. J. Dorschner, Dr. K. Euler, Dr. M. Green, Dr. S. Gödeke-Daub, Dr. G. Helfrich, Dr. A. Jablonski, Dr. A. Jaschke-Eberhardt, Dr. S. Klimaschewski, Dr. W. Laforsch, Dr. S. Mieke, Dr. U. Nüsse, Dr. C. von Rauch, Dr. C. Schneider, Dr. W. Seher,
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