The progression of Parkinson’s disease over 2 years takes a toll on the driving skills of even drivers who initially perform as well as healthy age-matched drivers, according to a longitudinal cohort study conducted by Urgun Uc, MD, and associates.

While some patients with Parkinson’s disease who took part in a test of driving skills on a standardized driving course performed significantly worse at a baseline assessment than did healthy control patients, the patients who performed at a similar level as the control group made a significantly higher number of driving mistakes 2 years later on a follow-up evaluation.

Overall, at baseline, 67 Parkinson’s disease patients committed more road safety errors and also performed worse on visual, cognitive, and motor tests than did 110 members of the control group. At baseline, the Parkinson’s disease group made an average of 40.6 road safety errors, and the control group made 32.9 mistakes.

Among the original 67 Parkinson’s disease patients, the 28 who returned for repeat testing at 2 years had performed just as well at baseline as the 69 control group returnees. But at the 2-year follow-up, the Parkinson’s disease group made an average of 49.7 mistakes, while the control group made 34.6 mistakes.

In addition to an increase in overall driving errors, Parkinson’s disease patients also made a significantly higher number of lane observance, overtaking, turning, miscellaneous, and serious errors after 2 years than did the control group. Risk factors for worse performance after 2 years included greater error count and worse visual acuity at baseline, and worsening of global cognition, Unified Parkinson’s Disease Rating Scale scores, executive function, visual-processing speed, and attention.

“Health care providers for patients with Parkinson’s disease should routinely inquire about driving status and make necessary referrals for evaluation of driving fitness as needed. Further research is needed to determine if improvement of underlying impairments in visual perception, executive function, and motor abilities through physical exercise and cognitive training can preserve driving ability in Parkinson’s disease for a longer time,” the investigators concluded.

Read the full study in Neurology ( doi: 10.1212/WNL.0000000000004629 ).