The effects of cognitive abilities on driving in people with Parkinson's disease

Objective : The aim was to develop a cognitive screening procedure, which could be used to identify cognitive problems in patients with Parkinson's disease, which might affect their safety to drive. Design : Two group comparison of those found safe to drive and those found unsafe. Setting : People living in the community who were attending an outpatient Movement Disorders clinic or who had been referred to a Regional Mobility Centre. Participants : Fifty-one people with Parkinson's disease who were driving or who wished to resume driving. The 41 men and 10 women were aged 44 - 85 years (mean 64.4 SD 9.1). Main measures : Webster's Rating Scale, Unified Parkinson's Disease Rating Scale motor examination, Stroke Drivers Screening Assessment, Adult Memory and Information Processing Battery, Stroop, Paced Auditory Serial Addition Task and a Tapping task. Results : The unsafe drivers were significantly more disabled, as assessed on Webster's Scale, than those who were found safe to drive. There were no significant differences in the cognitive abilities of safe and unsafe drivers. The most common faults, which caused drivers to be judged unsafe, were lack of observations to the side at junctions, poor positioning on the road and poor driving on roundabouts. There were significant correlations ( p < 0.05) between driving ability and performance on the SDSA Dot Cancellation task and the AMIPB Story Recall and Information Processing A. Conclusions : Cognitive abilities were not found to be associated with fitness to drive in people with Parkinson's disease. Webster's Rating Scale differentiated between safe and unsafe drivers. This could be used to determine who to refer to a mobility centre for advice on fitness to drive.