Temporal course of depressive symptoms during the development of Alzheimer disease

Abstract

Objective: To characterize change in depressive symptoms before and after the onset of dementia in Alzheimer disease (AD).

Method: We used data from the Chicago Health and Aging Project, a longitudinal cohort study of risk factors for AD in a geographically defined population of old people. Two subsets were analyzed. In 357 individuals who developed incident AD during the study, self-report of depressive symptoms (Center for Epidemiologic Studies Depression Scale) was obtained at 3-year intervals for a mean of 8 to 9 years. In 340 individuals who agreed to annual data collection, informant report of depressive symptoms (Hamilton Depression Rating Scale) was obtained for a mean of 3 years after a diagnosis of AD (n = 107), mild cognitive impairment (n = 81), or no cognitive impairment (n = 152).

Results: The incident AD group reported a barely perceptible increase in depressive symptoms during 6 to 7 years of observation before the diagnosis (0.04 symptoms per year) and no change during 2 to 3 years of observation after the diagnosis except for a slight decrease in positive affect. In those with annual follow-up, neither AD nor its precursor, mild cognitive impairment, was associated with change in informant report of depressive symptoms during a mean of 3 years of observation.

Conclusion: Depressive symptoms show little change during the development and progression of AD to a moderate level of dementia severity.

Figure 1 Change in self-report of depressive symptoms. Predicted 9-year path of change in self-report of depressive symptoms in a typical participant diagnosed with Alzheimer disease at year 6.

Figure 2 Change in informant report of depressive symptoms Predicted 3-year paths of change in informant report of depressive symptoms in persons with no cognitive impairment (black line), mild cognitive impairment (blue line), or Alzheimer disease (red line), adjusted for age, sex, race, and education.