Impact of depressive symptoms on the rate of progression to dementia in patients affected by mild cognitive impairment. The Italian Longitudinal Study on Aging

Background Mild cognitive impairment (MCI) is often a prodromal of dementia and depressive symptoms have been suggested as risk factor for dementing disorders. We evaluated the possible impact of depressive symptoms on the rate of progression to dementia in MCI patients after a 3.5-year follow-up; and the interaction between depressive symptoms and vascular risk factors for conversion to dementia. Methods A total of 2,963 individuals from a sample of 5,632 65-84 year old subjects were evaluated at the first (1992-1993), and second survey (1995-1996)of the Italian Longitudinal Study on Aging (ILSA), a prospective cohort study. MCI and dementia were classified using current clinical criteria. Depressive symptoms were measured with the Geriatric Depression Scale. Results Among the 2,963 participants, 139 prevalent MCI patients were diagnosed at the first survey. During the 3.5-year follow-up, 14 MCI patients progressed to dementia, and we did not find any significant relationship between depressive symptoms and rate of progression to dementia (RR 1.42, 95% CI, 0.48-4.23, chi(2) 0.40, p < 0.53). No socio-demographic variables or vascular risk factors modified the association between depressive symptoms and conversion to dementia. Conclusions In our population, depressive symptoms were not associated with the rate of progression to dementia in MCI patients. Our findings did not support a role of socio-demographic variables or vascular risk factors in the association of depressive symptoms and conversion to dementia. Copyright (C) 2008 John Wiley & Sons, Ltd.