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Background/aims: (1) To investigate how specific executive functions change over 2 years in drivers with Parkinson's disease (PD) compared to controls, using both neuropsychological and driving simulator tasks; and (2) to explore the association between the decline of specific executive functions and changes in driving habits in PD., Methods: Sixteen PD patients and 21 controls underwent neuropsychological testing twice and performed tasks on a driving simulator, with an interval of approximately 2 years. Questions on participants' self-perception of their driving ability were administered., Results: A significant decline was observed in shift cost over time (Plus Minus Test) in patients (p = 0.008). This decline was greater in patients than in controls (p = 0.008). No significant change emerged over time in the flexibility cost of PD patients on a simulator (p = 0.158). Significant correlations were found between the decline in shift cost over time and driving question outcomes (p < 0.05)., Conclusion: This study reveals a differential course of executive functions in PD. Over time, patients displayed significant decline in flexibility associated with modifications in their driving. Flexibility seems to be affected as the disease progresses. This research opens new avenues in cognitive and driving rehabilitation., (© 2016 S. Karger AG, Basel.)

Executive functions encompass various cognitive processes and are critical in novel or demanding driving situations. Our aim was to determine the role of impairments in specific executive functions (updating, flexibility, inhibition) on road performance in drivers with Parkinson's disease (PD), a condition commonly associated with early executive dysfunction. In this pilot study, 19 patients with mild to moderate PD and 21 healthy controls matched for age, education, and driving experience were tested using a neuropsychological battery assessing global cognitive abilities, updating (n-back task), flexibility (plus-minus task), and inhibition (Stroop test). Participants also underwent a 45-minute road test in which they were scored by a driving instructor and a second experimenter. To separate "at-risk" drivers from safe drivers, a composite driving indicator was calculated from the Test Ride for Investigating Practical Fitness to Drive score, the penalty score from the observation grid, and the number of safety interventions made by the driving instructor. Eight of the 40 drivers (all PD) were rated as "at risk." Measures of updating (the n-back task) and mental flexibility (the plus-minus task) predicted driving safety even after adjustment for group status, explaining 53% of the total variance. These 2 tests also discriminated between safe and "at-risk" drivers within the PD group. These findings, although preliminary, suggest that updating and mental flexibility are critical for safe driving in PD. Assessment batteries for driving fitness should probe different aspects of executive functions, specifically when evaluating drivers with PD., (© 2013 Movement Disorder Society.)

Alterations in cognitive functions in Parkinson's disease (PD) have been reported even in mild stages of the disease. These functions may play a role in complex daily activities, such as driving. This article provides an overview on the relationships between cognitive functions and driving behavior in PD in driving simulator and on-road studies. The role of attention, executive functions, visual memory, visuospatial construction and information processing speed is discussed. In driving simulator studies, driving performances were correlated with several neuropsychological measures, especially those of Trail Making Test (TMT), Brixton and Symbol Digit Modalities Test. In on-road studies, TMT, Useful Field Of View and Block Design tests appear as good predictors of driving performances. Most of these tests are also relevant to driving in Alzheimer's disease and traumatic brain injury. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]