Background: It is uncertain whether self- and proxy-reported cognitive decline in older adults reflect an actual objective cognitive dysfunction in the clinical sense, and if these are predictive for developing dementia.
Objective: The aim of the present study is to investigate the cross-sectional and longitudinal relation between subjective cognitive decline and objective cognitive performance, depressive symptoms, and to determine the predictive value for development of dementia.
Methods: We included 405 patients without dementia at first visit from the Maastricht memory clinic participating in a longitudinal cohort study. Subjective cognitive decline was measured using a self- and proxy-report questionnaire. All patients underwent a standardized neuropsychological assessment. Follow-up assessments were performed yearly for three consecutive years, and once after five years.
Results: Subjective cognitive decline was associated with lower cognitive performance and more depressive symptoms. When comparing self- (n = 342, 84%) and proxy-reported decline (n = 110, 27%), it was shown that proxy reports were associated with a more widespread pattern of lower cognitive performance. In participants without cognitive impairment proxy-reported decline was not associated with depressive symptoms. In contrast, self-reported decline was associated with a stable course of depressive symptoms at follow-up. Proxy-reported cognitive decline (HR = 1.76, 95% CI = 1.12- 2.78), and mutual complaints (HR = 1.73, CI:1.09- 2.76) predicted incident dementia while self-reported decline did not reach statistical significance (HR = 1.26, 95% CI = 0.65- 2.43).
Conclusion: Proxy-reported cognitive decline was consistently associated with lower cognitive performance and conversion to dementia over 5 years. Self-reported cognitive decline in patients without cognitive impairment might indicate underlying depressive symptoms and thus deserve clinical attention as well.
Keywords: Cognition; dementia; depressive symptoms; mild cognitive impairment; proxy-report; subjective cognitive decline.