Effect of Cognitive Reserve on Physiological Measures of Cognitive Workload in Older Adults with Cognitive Impairments

Article type: Research Article

Authors: Devos, Hannes^{a; b; *} | Gustafson, Kathleen M.^{c; d} | Liao, Ke^d | Ahmadnezhad, Pedram^a | Kuhlmann, Emily^a | Estes, Bradley J.^a | Martin, Laura E.^{d; e} | Mahnken, Jonathan D.^{b; f} | Brooks, William M.^{b; c; d} | Burns, Jeffrey M.^{b; f}

Affiliations: [a] Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, Kansas City, KS, USA | [b] University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, USA | [c] Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA | [d] Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, KS, USA | [e] Department of Population Health, University of Kansas Medical Center, Kansas City, KS, USA | [f] Department of Biostatistics & Data Science, University of Kansas Medical Center, Kansas City, KS, USA

Correspondence: [*] Correspondence to: Hannes Devos, Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, MS2002, 3901 Rainbow Blvd., Kansas City, KS, USA. Tel.: +1 913 588 5840; E-mail: hdevos@kumc.edu.

Abstract: Background:Cognitive reserve may protect against cognitive decline. Objective:This cross-sectional study investigated the association between cognitive reserve and physiological measures of cognitive workload in older adults with cognitive impairment. Methods:29 older adults with cognitive impairment (age: 75±6, 11 (38%) women, MoCA: 20±7) and 19 with normal cognition (age: 74±6; 11 (58%) women; MoCA: 28±2) completed a working memory test of increasing task demand (0-, 1-, 2-back). Cognitive workload was indexed using amplitude and latency of the P3 event-related potential (ERP) at electrode sites Fz, Cz, and Pz, and changes in pupillary size, converted to an index of cognitive activity (ICA). The Cognitive Reserve Index questionnaire (CRIq) evaluated Education, Work Activity, and Leisure Time as a proxy of cognitive reserve. Linear mixed models evaluated the main effects of cognitive status, CRIq, and the interaction effect of CRIq by cognitive status on ERP and ICA. Results:The interaction effect of CRIq total score by cognitive status on P3 ERP and ICA was not significant. However, higher CRIq total scores were associated with lower ICA (p = 0.03). The interaction effects of CRIq subscores showed that Work Activity affected P3 amplitude (p = 0.03) and ICA (p = 0.03) differently between older adults with and without cognitive impairments. Similarly, Education affected ICA (p = 0.02) differently between the two groups. No associations were observed between CRIq and P3 latency. Conclusion:Specific components of cognitive reserve affect cognitive workload and neural efficiency differently in older adults with and without cognitive impairments.

Keywords: Aging, cognitive dysfunction, cognitive reserve, electroencephalography, evoked potentials, memory, pupil, short-term

DOI: 10.3233/JAD-220890

Journal: Journal of Alzheimer's Disease, vol. 92, no. 1, pp. 141-151, 2023