Severity of Depression Impacts Imminent Conversion from Mild Cognitive Impairment to Alzheimer's Disease

Mild cognitive impairment (MCI) has been suggested to represent a prodromal stage of dementia and to confer a high risk for conversion to dementia Alzheimer's type (DAT).

In this study, we examined the predictive value of depressive symptoms and neuropsychological variables on conversion of MCI to DAT.

Neuropsychological and clinical follow-up data of 260 MCI patients seen at the Psychiatric Memory Clinic of the Medical University of Innsbruck between 2005 and 2015 were analyzed retrospectively. Depression was assessed using the Geriatric Depression Scale (GDS). Potential predictors of conversion from MCI to DAT were analyzed by logistic regression analyses and additional survival-analytic methods.

Of the 260 patients (mean age 71.5±7.7 years), 83 (32%) converted to DAT within a mean follow-up time of 3.2±2.2 years and estimated one-year conversion rate of 10.1%. The univariate analysis showed with few exceptions (gender, use of antidepressants, low GDS score) group differences at baseline in patients converted to DAT compared to stable MCI patients. Logistic regression analysis as well as survival analysis revealed moderate to severe depression together with higher age and specific cognitive deficits as predictors of conversion from MCI to DAT.

Our results support the predictive value of different neuropsychological measures on the progression of DAT. In addition, we found a strong negative influence of depression on conversion to DAT in MCI patients. These results emphasize the importance of assessing depressive symptoms in the early stages of DAT when evaluating the conversion from MCI to DAT.