Tortuosity in Movement Paths Is Related to Cognitive Impairment

W. D. Kearns; V. O. Nams; J. L. Fozard

doi:10.3414/ME09-01-0079

Methods of Information in Medicine, Table of Contents

Methods Inf Med 2010; 49(06): 592-598
DOI: 10.3414/ME09-01-0079

Original Articles

Schattauer GmbH

Tortuosity in Movement Paths Is Related to Cognitive Impairment

Wireless Fractal Estimation in Assisted Living Facility Residents

Authors

W. D. Kearns

¹Department of Aging and Mental Health, Louis de la Parte Florida Mental Health Institute, College of Behavioral and Community Sciences, University of South Florida, Tampa, FL, USA
V. O. Nams

²Department of environmental Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada
J. L. Fozard

³School of Aging Studies, College of Behavioral and Community Sciences, University of South Florida, Tampa, FL, USA

Abstract

Summary

Background: Using traditional assessment procedures, prior research demonstrated that deficiencies in gait and balance occur in the later stages of dementia.

Objective: We tested the hypothesis that an automated system capable of detecting path tortuosity (irregular movement) in elders would show that greater tortuosity was associated with greater cognitive impairment, potentially allowing early detection of dementia over time as tortuosity levels slowly increased.

Methods: An ultra-wideband sensor network using wireless transponders measured daytime locomotion to an accuracy of 20 cm in 14 elderly residents in an assisted living facility (ALF) as they traversed a shared living area while performing daily activities such as going to a dining area, conversing and watching television. Transponder location was updated at 0.4 sec intervals while in motion and revealed large individual differences in activity patterns.

Results: Fractal dimension (Fractal D), a measure of movement path tortuosity (directed vs. irregular or apparently aimless locomotion) was significantly and negatively correlated with cognitive status as measured by the Mini Mental State Examination administered to each participant at the study’s end.

Conclusions: Previous studies of locomotion in laboratory settings that have demonstrated gait variability increases with poor cognitive status have necessarily controlled various components of gait. The present results demonstrate that directional changes and other locomotion components can be studied by monitoring free movements in normal living settings over time. Implications for assessment and management of dementia-related wandering are discussed.

Keywords

Cognitive impairment - dementia - wandering - tracking technology - path tortuosity

Full Text

References

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