Motivational Symptoms of Depression Mask Preclinical Alzheimer’s Disease in Elderly Subjects

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Abstract
Althoughthe relationship between depressive disorders and Alzheimer's disease (AD) is debated, there is evidence that depression may be an early symptom of dementia. To evaluate depression features prospectively in elderly subjects with a view to identifying a subgroup affected by preclinical AD. We performed a cohort study on cognitive performances with a 12-month follow-up in out-patients referred to the local Neuropsychology Clinic complaining of memory problems. Two hundred and twenty-two consecutive non-demented subjects were studied using a neuropsychological battery and the Beck Depression Inventory (BDI) and assessed again 1 year later for the possible onset of cognitive impairment. Multivariate analysis was performed to detect independent predictors of dementia development among age, education, neuropsychological test scores and BDI scores and subscores. BDI subscores were obtained by dividing items into three domains corresponding to mood-related, somatic and motivation-related symptoms. At the time of the first evaluation, 124 of the 222 subjects were depressed according to DSM-III-R criteria. At 1 year, 31 of the 124 depressed subjects and 2 non-depressed ones had AD according to NINCDS-ADRDA criteria. Stepwise logistic regression analysis indicated that the subjects who went on to develop dementia had significantly higher total BDI scores and motivational BDI subscores. Among depressed subjects, the probability of being diagnosed with dementia during follow-up was significantly associated with a motivational BDI subscore > or = 7 (odds ratio: 3,885, 95% Cl 154-97,902). Close neuropsychological follow-up of depressed elderly subjects complaining of memory failure and showing apathy is recommended to detect the early stage of AD.