Objectives: To determine the relationship between depressed mood and the development of Alzheimer disease in cognitively normal individuals.
Design: Longitudinal and observational.
Setting: Community-based cohort study.
Participants: A total of 288 participants in the Cardiovascular Health Study-Cognition Study (mean age: 77.52, SD =3.65, range: 70-89). All of the participants were adjudicated as cognitively normal in 1998/1999, and all had at least three visits before 1998/1999 with measures of cognition and mood state. The mean length of follow-up from 1998-1999 to 2007 was 7.1 years (range: 1-9 years, median =9 years).
Measurements: The Center for Epidemiological Studies-Depression Scale (CESD) was used to index mood state, and the Modified Mini-Mental State Examination (3MSE) was the index of cognitive function among participants before 1998/1999. These measures were considered in two ways: participants were classified according to: 1) whether they showed a high-negative correlation between their CESD and 3MSE scores (i.e., indicating that greater depression was linked to poorer cognition) and 2) whether they showed persistently elevated CESD scores. The study outcome, development of dementia (N = 48), was based on consensus classifications, which was based on detailed neuropsychological and neurological exams.
Results: The authors could find no consistent relationship between mood state, either alone or in relation to cognitive status, and the subsequent development of dementia. Those individuals whose cognitive functions were highly correlated with their mood state were no more likely to develop dementia than other participants. Those who had persistently depressed mood were also no more likely to develop dementia than those without persistently depressed mood.
Conclusion: Within the confines of this prospective, community-based study of elderly adults, the authors could not find strong evidence to support the hypothesis that mood disturbance was linked with the development of dementia.