Objective of this study was to investigate whether specific motor and cognitive tests performed in clinic can predict behind-the-wheel driving behavior (DB) in Parkinson’s disease (PD).

DB is negatively affected in PD, with studies revealing increased risk for car accidents in PD drivers. Studies have attributed these results to motor (rigidity and bradykinesia) and cognitive (executive and visuospatial) deficits, but with no robust association.

Twenty-three patients with PD (Age: 63.39 ± 10.29;) and twenty-three propensity matched healthy controls (Age: 58.30 ± 10.88;) were enrolled through the outpatient clinics of the University of Athens with inclusion criteria of Hoehn &Yahr scale ≤ 3, a valid driver’s license, regular car driving, and no dementia. All participants underwent through clinical exams (motor function was quantified through Tandem Walking Test, Tandem Walking-Reverse Number Counting, Rapid Paced Walk, Head Rotation Task, Foot Tapping Test), neuropsychological assessment of global cognition, memory, visuospatial, processing speed, attention, executive function, and driving evaluation in a driving simulator. Factor analysis for motor, cognitive and driving variables revealed latent factors for  Driving (Tactical Driving Praxis, Operational Safety, Car Road Positioning, Tactical Driving related Accidents, Reaction Time Related Accidents), Motor (Motor Speed-Dexterity, Axial Movement) Cognitive (Planning-Processing Speed, Visuospatial Attention-Planning, Verbal Learning-Memory).

PD participants drove slower, with variable headway distance, with worse motor function and cognitive performance in verbal recall, visuospatial perception an executive functions  (p<0.05 Bonferroni corrected). Tactical Driving Praxis was predicted through Axial Movement, Speed-Dexterity, Planning-Processing Speed (F=14.4; p=5x10^-6), Car Road Positioning through Planning-Processing Speed, Visuospatial Attention (F=5.3; p=0.01), Reaction Time Related Accidents through Axial Movement, Learning and Memory, Visuospatial Attention and Planning (F=7.8; p=0.001).

Motor and cognitive phenotypes derived from   daily clinical practice can help predict behind-the-wheel DB in PD, allowing guidance on which patients should undergo formal assessments and who may need to stop driving.