Are specific symptoms of depression predictive of Alzheimer's dementia?

To investigate whether specific symptoms of major depression are associated with later development of possible or probable Alzheimer's dementia.

The analysis is part of the Vienna Transdanube Aging Study, a prospective, community-based cohort study of all 75-year-old inhabitants of 2 Viennese districts. Current depressive symptoms were captured with a DSM-IV-TR-based questionnaire. Diagnosis of possible or probable Alzheimer's dementia was performed according to criteria by the National Institute of Neurologic and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association. The baseline sample included 437 not-demented and not previously depressed individuals. At 60-month follow-up, 65 of the remaining 296 subjects had possible or probable Alzheimer's dementia. The primary outcome measure was the probability of diagnosis of Alzheimer's dementia related to baseline depressive symptoms. Baseline data were collected between May 2000 and December 2002; 60-month follow-up data were collected between June 2005 and February 2008.

10.8% of those who were diagnosed with possible or probable Alzheimer's dementia at 60-month follow-up had shown loss of interest versus 2.2% in the nondemented group. The analysis showed a significant association of loss of interest only with the later occurrence of possible or probable Alzheimer's dementia (adjusted P value <.05, OR = 5.27 [95% CI, 1.62-17.2], area under the receiver operating characteristic curve = 0.541). The specificity of this symptom in predicting Alzheimer's dementia was 97.8, and the sensitivity was 10.4.

Of 9 symptoms of depression, only loss of interest was associated with the development of Alzheimer's dementia over a period of 5 years in a sample of 75-year-old not-demented, never-depressed subjects, suggesting that depressive symptoms in the elderly are mostly symptoms of genuine depression.