Subjective memory decline predicts greater rates of clinical progression in preclinical Alzheimer's disease

Abstract

Introduction: The objective of this study was to determine the utility of subjective memory decline (SMD) to predict episodic memory change and rates of clinical progression in cognitively normal older adults with evidence of high β-amyloid burden (CN Aβ+).

Methods: Fifty-eight CN Aβ+ participants from the Australian Imaging, Biomarkers, and Lifestyle study responded to an SMD questionnaire and underwent comprehensive neuropsychological assessments. Participant data for three follow-up assessments were analyzed.

Results: In CN Aβ+, subjects with high SMD did not exhibit significantly greater episodic memory decline than those with low SMD. High SMD was related to greater rates of progression to mild cognitive impairment or Alzheimer's disease (AD) dementia (hazard ratio = 5.1; 95% confidence interval, 1.4-20.0, P = .02) compared with low SMD. High SMD was associated with greater depressive symptomatology and smaller left hippocampal volume.

Discussion: High SMD is a harbinger of greater rates of clinical progression in preclinical AD. Although SMD reflects broader diagnostic implications for CN Aβ+, more sensitive measures may be required to detect early subtle cognitive change.

Keywords: Amyloid; PET imaging; Preclinical AD; Prodromal AD; Subjective cognitive decline; Subjective memory decline cognitively normal older adults.