Objective: To examine the relationship of β-amyloid (Aβ) deposition to episodic memory in younger (30-49 years), middle-older (50-69 years), and older adults (70-89 years). We hypothesized that subclinical levels of amyloid would be linked to memory in adults across the lifespan in a dose-dependent fashion. Of great interest was whether, within the younger group, a relationship between amyloid level and memory performance could be established.
Methods: A total of 147 participants from the Dallas Lifespan Brain Study, aged 30-89, underwent PET imaging with 18F-florbetapir and cognitive assessment. We assessed the relationship between age group and amyloid and tested whether Aβ differentially affected memory performance across the 3 age groups.
Results: We report a significant association of age to amyloid burden for younger and middle-older adults (r = 0.57 and 0.28, respectively), but not for the oldest group, although absolute level of amyloid increased across the age groups. Importantly, the youngest group showed a significant decrease in recall (r = -0.47, p = 0.004) and recognition memory (r = -0.48, p = 0.003) as a function of increases in Aβ burden, whereas this relationship was absent in the middle-older and oldest group (all p > 0.23).
Conclusions: These results indicate that variance in subclinical levels of Aβ in younger adults is meaningful, and suggest that higher SUVRs relative to one's peers at a younger age is not entirely benign.
© 2016 American Academy of Neurology.