Cognitive workload during verbal abstract reasoning in Parkinson’s disease: a pilot study

Abstract

Background

Pupillary response reflects cognitive workload during processing speed, working memory, and arithmetic tasks in Parkinson’s disease (PD). Abstract reasoning, a higher-order cognitive function that relates different objects, events, or thoughts in a similar manner, may also be compromised in PD. The aim of this study was to compare pupillary response as a measure of cognitive workload while completing a verbal abstract reasoning test between patients with PD and age-matched controls.

Methods

Nineteen non-demented individuals with PD (66.6 ± 8.9 years) and 10 healthy controls (65.3 ± 7.3 years) were recruited. A remote eye tracker recorded the pupillary response at 60 Hz, while the participants were performing the Similarities test of Wechsler Adult Intelligence Scale-IV. Outcome measures included pupillary response, evaluated by the Index of Cognitive Activity (ICA), and behavioral responses of the Similarities test.

Results

The PD group (scaled scores = 8.9 ± 2.2) did not show impairment in behavioral performance on Similarities test compared with healthy controls (scaled scores = 8.8 ± 2.3; p = .91). However, the PD group (ICA = .32 ± .09) demonstrated significantly greater cognitive workload during the Similarities test compared to controls (ICA = .24 ± .08; p = .03).

Conclusions

Non-demented individuals with PD exerted greater cognitive workload to complete a verbal abstract reasoning task despite similar behavioral performance compared to healthy controls. Clinical utilities of pupillary response to detect and monitor early impairment in higher-order executive function will be the subject of further study in the PD population.

Keywords:

• Pupillary response
• cognitive workload
• cognition
• Parkinson’s disease
• verbal reasoning
• abstract reasoning

Disclosure statement

No potential conflict of interest was reported by the author(s).

Acknowledgements

The authors would like to thank the participants of this study. The authors acknowledge the contributions of Viswa Gangeddula (University of Kansas Medical Center, Kansas City, KS) and Mikaela Bell (Rockhurst University, Kansas City, MO) for their help with data collection and entry.

Notes on contributors

HD conceptualized the study. SM, MK, and HD drafted the manuscript and analyzed the data. HD, AEA, KEL, and RP made valuable suggestions and reviewed the manuscript.

Additional information

Funding

This work was supported by the American Parkinson’s Disease Association (PI: HD) and by the T32HD057850 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (MK).