Objective: The prevalence of dementia continues to rise, and yet, there are few known modifiable risk factors. Depression, as a treatable condition, may be important in the development of dementia. Our objective was to examine the association between depressive symptoms and longitudinal cognitive changes in older adults who were high-functioning at baseline.
Methods: The authors analyzed data from a community-based cohort (aged 70-79 at baseline), who, at study entry, scored 7 or more (out of 9) on the Short Portable Mental Status Questionnaire (SPMSQ). Depressive symptoms were assessed at baseline using the depression subscale of the Hopkins Symptom Check List. Cognitive performance was measured at baseline and at seven-year follow up by the SPMSQ and by summary scores from standard tests of naming, construction, spatial recognition, abstraction, and delayed recall.
Results: After adjusting for potential confounders, including age, education, and chronic health conditions such as diabetes, heart attack, stroke, and hypertension, a higher number of baseline depressive symptoms were strongly associated with greater seven-year decline in cognitive performance and with higher odds of incident cognitive impairment, i.e., decline in SPMSQ score to < or = 6 (adjusted odds ratio per quartile of depressive symptoms score: 1.34, 95% confidence interval: 1.10-1.68).
Conclusions: Depressive symptomatology independently predicts cognitive decline and incident cognitive impairment in previously high-functioning older persons.