The occurrence of depressive symptoms in the preclinical phase of AD: a population-based study.

To examine preclinical depressive symptoms 3 years before the diagnosis of AD. The authors compared incident AD patients and nondemented individuals in terms of baseline mood- and motivation-related symptoms of depression, and assessed whether depressive symptoms in preclinical AD are related to self-perceived memory problems. Participants came from a population-based longitudinal study on aging and dementia in Stockholm, Sweden. The sample consisted of 222 persons older than 74 years who were followed for a 3-year interval. Thirty-four individuals had developed AD at follow-up, whereas 188 remained nondemented. Dementia diagnosis was made according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised. Depressive symptoms were assessed by the Comprehensive Psychopathological Rating Scale. The incident AD patients had more depressive symptoms than the nondemented persons at baseline. There was a dominance of motivation-related symptoms of depression (e.g., lack of interest, loss of energy, concentration difficulties) in preclinical AD. This association remained when adjusting for subjective memory complaints. Depressive symptoms are elevated preclinically in AD, and this elevation is not merely a by-product of self-perceived cognitive difficulties. Thus, depressive symptoms may be part of the preclinical phase in AD.