Effects of beta-amyloid accumulation on neural function during encoding across the adult lifespan

Kristen M. Kennedy, Karen M. Rodrigue, Michael D. Devous, Andrew C. Hebrank, Gérard N. Bischof, Denise C. Park

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

Limited functional imaging evidence suggests that increased beta-amyloid deposition is associated with alterations in brain function, even in healthy older adults. However, the majority of these findings report on resting-state activity or functional connectivity in adults over age 60. Much less is known about the impact of beta-amyloid on neural activations during cognitive task performance, or the impact of amyloid in young and middle-aged adults. The current study measured beta-amyloid burden from PET imaging using 18Florbetapir, in a large continuous age sample of highly-screened, healthy adults (N=137; aged 30-89years). The same participants also underwent fMRI scanning, performing a memory encoding task. Using both beta-amyloid burden and age as continuous predictors of encoding activity, we report a dose-response relationship of beta-amyloid load to neural function, beyond the effects of age. Specifically, individuals with greater amyloid burden evidence less neural activation in bilateral dorsolateral prefrontal cortex, a region important for memory encoding, as well as reduced neural modulation in areas associated with default network activity: bilateral superior/medial frontal and lateral temporal cortex. Importantly, this reduction of both activation and suppression as a function of amyloid load was found across the lifespan, even in young- and middle-aged individuals. Moreover, this frontal and temporal amyloid-reduced activation/suppression was associated with poorer processing speed, verbal fluency, and fluid reasoning in a subgroup of individuals with elevated amyloid, suggesting that it is detrimental, rather than compensatory in nature.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalNeuroImage
Volume62
Issue number1
DOIs
StatePublished - Aug 1 2012

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

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    Kennedy, K. M., Rodrigue, K. M., Devous, M. D., Hebrank, A. C., Bischof, G. N., & Park, D. C. (2012). Effects of beta-amyloid accumulation on neural function during encoding across the adult lifespan. NeuroImage, 62(1), 1-8. https://doi.org/10.1016/j.neuroimage.2012.03.077