Practice makes imperfect: stronger implicit interference with practice in individuals at high risk of developing Alzheimer's disease

Creators: Hung, Shao-Min; Adams, Sara W.; Molloy, Cathleen; Wu, Daw-An¹; Shimojo, Shinsuke¹; Arakaki, Xianghong

1. California Institute of Technology

Abstract

Early screening to determine patient risk of developing Alzheimer's will allow better interventions and planning but necessitates accessible methods such as behavioral biomarkers. Previously, we showed that cognitively healthy older individuals whose cerebrospinal fluid amyloid/tau ratio indicates high risk of cognitive decline experienced implicit interference during a high-effort task, signaling early changes in attention. To further investigate attention's effect on implicit interference, we analyzed two experiments completed sequentially by the same high- and low-risk individuals. We hypothesized that if attention modulates interference, practice would affect the influence of implicit distractors. Indeed, while both groups experienced a strong practice effect, the association between practice and interference effects diverged between groups: stronger practice effects correlated with more implicit interference in high-risk participants, but less interference in low-risk individuals. Furthermore, low-risk individuals showed a positive correlation between implicit interference and EEG low-range alpha event-related desynchronization when switching from high- to low-load tasks. This suggests that lower attention on the task was correlated with stronger interference, a typical phenomenon in the younger population. These results demonstrate how attention impacts implicit interference and highlight early differences in perception between high- and low-risk individuals.

Copyright and License

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Funding

We are grateful for the research funding provided by the James Boswell Postdoctoral Fellowship, the Caltech BBE Divisional Postdoctoral Fellowship, and the sub-award under the Aligning Consciousness Research with US Funding Mechanisms by Templeton World Charity Foundation (TWCF: 0495) to S-MH and LK, Whittier Foundation to HMRI, and the National Institute of Health R56 (R56AG063857) and R01 (R01AG063857) to SS and XA.

Contributions

Shao-Min Hung and Sara W. Adams contributed equally.

Data Availability

The current study was not preregistered. The raw data and code are available upon reasonable request.

Ethics

The institutional review boards (IRB) of the California Institute of Technology (IR19-0963) and the Huntington Medical Research Institutes (HMRI) (Quorum IRB, #27197) approved this study.

All participants gave written consent prior to participation.

Conflict of Interest

The authors declare no competing interests.

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