Exploring sex differences in the relationship between depressive symptoms and dementia incidence: prospective results from the PAQUID Study.

OBJECTIVES: To estimate the predictive relationship between depressive symptoms and 8-year dementia incidence in a large prospective community sample of French older adults and to compare the effect magnitude for men and women.
DESIGN: Prospective population-based cohort with four interview waves and complete vital status ascertainment.
SETTING: Urban and rural communities in the Aquitaine Region (Gironde and Dordogne), southwest France. PARTICIPANTS: Three thousand seven hundred seventy-seven adults aged 65 and older residing in noninstitutional settings at study baseline. MEASUREMENTS: Each participant was interviewed by a neuropsychologist and screened for dementia with the Mini-Mental State Examination, a cognitive test battery, and a standardized questionnaire designed to ascertain the presence of the criteria for dementia according to the Diagnostic and Statistical Manual for Mental Disorders, Third Edition, Revised (DSM-III-R). Dementia status and subtype were confirmed using neurological examination and categorized according to DSM-III-R criteria for dementia and the National Institute of Neurological Disorders and Stroke/Alzheimer's and Related Disorders Association criteria. The Hachinski score was calculated to specify the etiology: possible or probable Alzheimer's disease, vascular dementia, and other types of dementia. Depressive symptomatology was evaluated using the Center for Epidemiologic Studies-Depression scale. Statistical analyses were weighted to correct for attrition not due to mortality.
RESULTS: Ninety-seven men (incidence rate: 14.4/1,000) and 183 women (Incidence rate: 19.0/1,000) developed dementia during 8 years of follow-up. Baseline prevalence of depressive symptomatology was 12.9% for men and 14.7% for women. Depressive symptoms increased risk of dementia at subsequent interview wave, but only for men (odds ratio (OR) (men) = 3.5, 95% confidence interval (CI) = 1.9-6.5; OR (women) = 1.2, 95% CI = 0.7-2.0, P-value for sex difference = 0.03). The hypothesis that vascular depression might explain the observed sex difference was studied, and it was found that risk was 50% higher for men with hypertension who were depressed than for normotensive men. For women, hypertension status did not modify the absence of an association.
CONCLUSION: This study supports the hypothesis of a relationship between proximal depressive symptomatology and dementia in men, but distant depression did not increase dementia risk in this sample. The results suggest that depression in older men might reflect a form of vascular depression associated with cerebral vascular pathology or multiinfarct disease that may amplify the dementing or declining process, hence accelerating the onset of manifest symptoms of dementia.