Spared behavioral repetition effects in Alzheimer’s disease linked to an altered neural mechanism at posterior cortex

ABSTRACT

Objective: Individuals with dementia of the Alzheimer type (AD) classically show disproportionate impairment in measures of working memory, but repetition learning effects are relatively preserved. As AD affects brain regions implicated in both working memory and repetition effects, the neural basis of this discrepancy is poorly understood. We hypothesized that the posterior repetition effect could account for this discrepancy due to the milder effects of AD at visual cortex. Method: Participants with early AD, amnestic mild cognitive impairment (MCI), and healthy controls performed a working memory task with superimposed repetition effects while electroencephalography was collected to identify possible neural mechanisms of preserved repetition effects. Results: Participants with AD showed preserved behavioral repetition effects and a change in the posterior repetition effect. Conclusion: Visual cortex may play a role in maintained repetition effects in persons with early AD.

KEYWORDS:

• Alzheimer’s disease
• event-related potentials
• mild cognitive impairment
• repetition effects
• working memory

Acknowledgments

We would like to thank C. Black, S. Kiser, and E. Walsh for their assistance in behavioral data collection, and we would like to thank A. Lawson for assistance in task development. We would like to thank R. Kryscio, E. Abner, and the University of Kentucky Alzheimer Disease Center (UK-ADC) for their help with the compilation of the neuropsychological test results. We would like to thank J. Dien for assistance in use of his ERP Toolkit software. We have no financial or material conflicts of interest to report.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by a pilot grant from the University of Kentucky Department of Behavioral Science; the U.S. Department of Energy [grant number DE-AC03-OR22725]; and the National Institute of Health: National Institute on Aging [grant number P50 AG05144-21], [grant number AG000986], [grant number 5P30AG028383], [grant number 810 5 T32 AG 242-18], the National Institute of Mental Health [grant number R25 MH060482], and the National Center for Advancing Translational Sciences [grant number UL1RR033173], [grant number UL1TR000117].