2015 Articles

Aβ-related hyperactivation in frontoparietal control regions in cognitively normal elderly

Oh, Hwamee; Steffener, Jason; Razlighi, Qolamreza R.; Habeck, Christian; Liu, Dan; Gazes, Yunglin; Janicki, Sarah; Stern, Yaakov

The accumulation of amyloid-beta (Ab) peptides, a pathologic hallmark of Alzheimer’s disease, has been associated with functional alterations in cognitively normal elderly, most often in the context of episodic memory with a particular emphasis on the medial temporal lobes. The topography of Ab deposition, however, highly overlaps with frontoparietal control (FPC) regions implicated in cognitive control/ working memory. To examine Ab-related functional alternations in the FPC regions during a working memory task, we imaged 42 young and 57 cognitively normal elderly using functional magnetic resonance imaging during a letter Sternberg task with varying load. Based on 18F-florbetaben-positron emission tomography scan, we determined older subjects’ amyloid positivity (Abþ) status. Within brain regions commonly recruited by all subject groups during the delay period, age and Ab deposition were independently associated with load-dependent frontoparietal hyperactivation, whereas additional compensatory Ab-related hyperactivity was found beyond the FPC regions. The present results suggest that Ab-related hyperactivation is not specific to the episodic memory system but occurs in the PFC regions as well.