Higher Aβ burden in subjective memory complainers: A flutemetamol sub-study in AIBL

Objectives The underlying pathological process, diagnostic utility and prognostic value of subjective memory complaints (SMC) in relation to Alzheimer's disease (AD) remains unclear. The relationship between SMC and Aβ burden as assessed by 18F-flutemetamol was explored in healthy elderly controls (HC) with and without SMC and compared to participants with mild cognitive impairment (MCI) and AD patients.

Methods 187 AIBL participants who had not been previously imaged were evaluated: 134 HC (age 74.4±5.6), 42 MCI (age 73.9±6.2) and 11 mild AD patients (age 74.8±8.6). HC were further classified according to the presence (HC-SMC, n=80) or absence of SMC (non-memory complainers HC-NMC, n=54). All participants underwent a comprehensive neuropsychological examination, and a 3D T1 MP- RAGE MRI. 18F-flutemetamol images were acquired from 90-110 mins post-injection of 18F-flutemetamol and regional and global cortical SUVR were calculated using the pons as reference region. A SUVR cut-off of 0.62 was used to define scans as low (Aβ-) or high (Aβ+) Aβ burden.

Results About 91% of AD, 55% of MCI, and 22% of HC were deemed Aβ+. Despite normal neuropsychological scores, HC-SMC had significantly higher 18F-flutemetamol retention (0.54±0.14 vs. 0.49±0.10, respectively, p=0.026) and significantly higher prevalence of Aβ+ cases (33% vs. 7%, respectively, p=0.0006) than HC-NMC.

Conclusions Subjective memory complaint indicated increased risk of preclinical AD in this study population. Longitudinal follow-up of this cohort continues.

Research Support GE Healthcare