Brain Advance Access published online on August 8, 2007
Brain, doi:10.1093/brain/awm178
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Impaired navigation in drivers with Parkinson's disease
1Department of Neurology, University of Iowa, 2Neurology Service, Veterans Affairs Medical Center, 3Department of Mechanical and Industrial Engineering, University of Iowa, 4Public Policy Center, University of Iowa and 5Department of Biostatistics, University of Iowa, Iowa City, IA, USA
Correspondence to:
Ergun Y. Uc, MD, Department of Neurology, University of Iowa, Carver College of Medicine, 200 Hawkins Drive-2RCP, Iowa City, IA 52242 E-mail: ergun-uc{at}uiowa.edu
Navigating a new route during automobile driving uses the driver's cognitive resources and has the potential to impair driving ability in people with Parkinson's disease (PD). Our aim was to assess navigation and safety errors during a route following task (RFT) in drivers with the illness. Seventy-seven subjects with mild-moderate PD (median Hoehn–Yahr stage = 2.0) and 152 neurologically normal elderly adults, all active and licensed drivers, were tested with a battery of visual, cognitive and motor tests of abilities. Each driver also performed a RFT administered on the road in an instrumented vehicle. Main outcome variables included: number of incorrect turns, times lost and at-fault safety errors. All group comparisons were adjusted for age, gender, education and familiarity with the region. Drivers with PD performed significantly worse on cognitive, visual and motor tests compared to controls, and took longer to finish the RFT. Higher proportions of these drivers made incorrect turns {53.9% in PD versus 21.1% in controls, Odds Ratio (OR) [95% Confidence Interval (CI)] = 2.8 [1.4, 5.7], P = 0.006}, got lost (15.8% versus 2.0%, OR [95%CI] = 4.7 [1.1, 20.0], P = 0.037), or committed at-fault safety errors (84.2% versus 46.7%, OR [95%CI] = 7.5 [3.3, 17.0], P < 0.001). Within the patient group, the navigational and safety errors were predicted by poor performances on cognitive and visual tests, but not by the severity of motor dysfunction. Drivers with PD made more navigation and safety errors than neurologically normal drivers on a RFT that placed demands on driver memory, attention, executive functions and visual perception. The PD group driver safety was degraded possibly due to an increase in the cognitive load in patients with limited reserves. Navigational errors and lower driver safety were associated more with impairments in cognitive and visual function than the motor severity of their disease in drivers with PD.
Key Words: Parkinson disease; driving; cognition; vision; accident; traffic; automobile; navigation
Abbreviations: AVLT, Auditory Verbal Learning Test; BVRT, Benton Visual Retention Test; CFT, Complex Figure Test; COWA, Controlled Oral Word Association; CS, contrast sensitivity; ESS, Epworth Sleepiness Scale; FVA, far visual acuity; GDS, Geriatric Depression Scale; FR, functional reach; JLO, judgment of line orientation; MMSE, Mini Mental Status Examination; NVA, near visual acuity; PD, Parkinson's disease; SE-ADL, Schwab-England Activities of Daily Living; SFM, structure from motion; TMT, Trail Making Test; UFOV, Useful Field of View; UPDRS, Unified Parkinson's Disease Rating Scale.
Received February 23, 2007. Revised July 3, 2007. Accepted July 11, 2007.