By Ester Klimkeit, DPsych
Adjunct Senior Lecturer
School of Psychology and Psychiatry
Road safety of patients with neurodegenerative disorders such as Parkinson's Disease (PD) needs to be balanced with the loss of independence, reduction of activities and depression that is associated with driving cessation.1 While determination of risk typically lies with licensing authorities, in practical terms health practitioners are involved in decision-making about driving cessation in their patients, which may impact on the doctor-patient relationship, and on the disclosure of information by the patient.2
Interestingly, studies investigating driving cessation decision-making processes in individuals with PD, typically indicate that reliance on medical advice is rare2 and do not tend to be based on outcomes of on-road tests.3,4 Further, individuals with PD, controls and health professionals such as neurologists have been shown to overestimate ability to drive, compared to results of on-road driving assessments.5 This raises the question of how successful health professionals actually are at identifying potentially at-risk drivers, and what evidence there is to help assess this risk.
Most studies investigating whether or not individuals with PD have more motor-vehicle accidents than the general population are limited, lacking aged-matched controls. A recent large-scale study has found that younger individuals with PD are more likely to report causing an accident compared to age-matched controls; however, this difference diminished with age.6 Both driving simulator and on-road driving test studies suggest that there are impairments in driving ability in individuals with PD when compared to controls. Driving simulator studies typically show slower reaction times, slower movement speed, more collisions and difficulty maintaining lane position in the PD group.4,7, 8
Similarly, on-road driving studies tend to show lane keeping errors, reduced use of mirrors, difficulties reversing and parking, difficulties negotiating intersections, unsteady steering wheel movement and delayed decision making in individuals with PD.9,10 These studies typically investigate individuals with mild to moderate disease whilst "on" medication, and do not tend to have large enough samples to examine heterogeneity within the PD groups. It is of note that there is considerable variability among drivers with PD, with a proportion of drivers performing normally.11 More recently, studies have started to investigate the effect of different driving conditions on driving ability, informing on the potential usefulness of license restrictions. Drivers with PD have been shown to be at increased risk of unsafe driving on unfamiliar roads11, and under low contrast visibility driving conditions (e.g., fog or twilight).12 Further studies investigating time of day effects and weather conditions are warranted.
While a number of studies have investigated whether disease severity, disease duration and levadopa medication dosage can predict driving performance in PD, these have largely produced inconsistent results, making it very difficult to draw conclusions on this point.9 cf. 13 Dopaminergic medications have been linked to excessive daytime sleepiness and more rarely risk of daytime "sleep attacks".14 In order to show convincing evidence that road accidents due to excessive sleepiness are more frequent in patients with PD, future studies require age matched controls.
The relationship between driving performance and neuropsychological test performance has also been investigated, with a number of evident group differences in areas such as visual perception, attention, memory, slowed information processing, executive functioning and motor dexterity linked with driving performance in PD.5, 8, 15, 16 As yet, there is no consensus on a standard battery of tests that could accurately predict driving ability. Preliminary evidence is promising and suggests that neuropsychological screening batteries tend to explain <70% of variance in driving ability, and correctly classify over 70% of patients. 17, 18 Addition of clinical measures may further improve classification.17
Overall, while there is some evidence to guide doctors' decisions about patients' driving risk, evidence-based guidelines for assessing driving competency in people with neurodegenerative disease are lacking. Driving simulators offer the opportunity for safe and easily standardised test conditions, and refined neuropsychological screening batteries potential identification of persons requiring further comprehensive assessment. Further research into different driving conditions and capacity of drivers to compensate for functional impairments may provide more information on applicable license restrictions in PD. Also of interest is the benefit observed in (older) recipients of processing-speed and driving simulator training.19 As yet, there is no research into the efficacy of driver training/cognitive intervention programs on improved road safety in PD.
Note: Readers interested in recent review papers of driving ability in Parkinson's disease may be interested in:
Klimkeit, E.I., Bradshaw, J.L., Charlton, J., Stolwyk, R., Georgiou-Karistianis, 2009. Driving ability in Parkinson's disease: Current status of research. Neuroscience and Biobehavioural Reviews, 33, 223-231.
Uitti, R.J. 2009. Parkinson's disease and issues related to driving. Parkinsonism and Related Disorders, 15(S3), S122-S125
1 Fonda, S.J., Wallace, R.B., Herzog, A.R., 2001. Changes in driving patterns and worsening depressive symptoms among older adults. Journal of Gerontology 56B, S343-S352.
2 Cubo, E., Martin, P. M., Gonzalez, M., Bergareche, A., Campos, V., Fernandez, J. M., Alvarez, M., Bayes, A., Balzquez, R., 2010. What contributes to driving ability in Parkinson's disease. Disability and Rehabilitation, 32(5), 374-378
3 McLay, P., 1989. The Parkinsonian and driving. International Disability Studies 11, 50-51.
4 Zesiewicz, T.A., Cimino, C.R., Malek, A.R., Gardner, N., Leaverton, P.L., Dunne, P. B., Hauser, R.A., 2002. Driving safety in Parkinson's Disease. Neurology, 59(1), 1787-1788.
5 Heikkilä, V.M., Turkka, J., Korpelainen, J., Kallanranta, T., Summala, H., 1998. Decreased driving ability in people with Parkinson's Disease. Journal of Neurology, Neurosurgery and Psychiatry, 64, 325-330.
6 Meindorfner, C., Körner, Y., Möller, J.C., Stiasny-Kolster, K., Oertel, W.H., Krüger, H.P., 2005. Driving in Parkinson's Disease: Mobility, accidents and sudden onset of sleep at the wheel. Movement Disorders, 20(7), 832-842.
7 Lings, S., Dupont, E., 1992. Driving with Parkinson's disease: a controlled laboratory investigation. Acta Neurologica Scandinavica 86(1), 33-39.
8 Stolwyk, R.J., Charlton, J.L., Triggs, T.J., Iansek, R., Bradshaw, J. L. 2006. Neuropsychological function and driving ability in people with Parkinson's disease. Journal of Clinical and Experimental Neuropsychology 28, 898-913.
9 Cordell, R., Lee, H.C., Granger, A., Vieira, B, Lee, A.H., 2008. Driving assessment in Parkinson's disease - a novel predictor of performance? Movement Disorders, 23(9), 1217- 1222.
10 Wood, J.M., Worringham, C., Kerr, G.K., Mallon, K., Silburn, P., 2005. Quantitative assessment of driving performance in Parkinson's disease. Journal of Neurology, Neurosurgery and Psychiatry, 76, 176-180.
11 Uc, E.Y., Rizzo, M., Johnson, A.M., Dastrup, E., Anderson, S.W., Dawson, J.D. 2009. Road safety in drivers with Parkinson disease. Neurology, 73, 2112-2119.
12 Uc, E.Y., Rizzo, M., Anderson, S.W., Dastrup, E., Sparks, J. D., Dawson, J. D. 2009. Driving under low-contrast visibility conditions in Parkinson disease. Neurology, 73, 1103-1110.
13 Devos, H., Vandenberghe, W., Nieuwboer, A., Tant, M., Baten, G., De Weerdt, W., 2007. Predictors of fitness to drive in people with Parkinson's disease. Neurology, 69, 1434-1441.
14 Frucht, S., Rogers, J.D., Greene, P.E., Gordon, M.F., Fahn S., 1999. Falling asleep at the wheel: motor vehicle mishaps in persons taking pramipexole and ropinirole. Neurology, 52, 1908-1910.
15 Uc, E. Y., Rizzo, M., Anderson, S.W., Sparks, B.A., Rodnitzky, R.L. Dawson, J. D., 2006. Driving with distraction in Parkinson disease. Neurology, 67, 1774- 1780.
16 Radford, K. A., Lincoln, N. B., Lennox, G., 2004. The effects of cognitive abilities on driving in people with Parkinson's disease. Disability and Rehabilitation, 26(2), 65-70.
17 Worringham, C.J., Wood, J.M., Kerr, G.K., Silburn, P., 2006. Predictors of driving assessment outcome in Parkinson's disease. Movement Disorders 21(2), 230-235.
18 Amick, M.M., Grace, J., Ott, B.R., 2007. Visual and cognitive predictors of driving safety in Parkinson's disease patients. Archives of Clinical Neuropsychology, 22(8), 957- 967.
19 Roenker, D.L., Cissell, G.M., Ball, K.K., Wadley, V.G., Edward, J. D., 2003. Speed-of- processing and driving simulator training result in improved driving performance. Human Factors, 45, 218-233.
About Ester Klimkeit
Ester Klimkeit, DPsych (clinical), is holds an adjunct senior lecturer position in the School of Psychology and Psychiatry at Monash University and is employed as a senior clinical psychologist by Southern Health, in Melbourne Australia. She finished her doctorate in 2003, where she developed an interest in clinical psychology and neuropsychology. She is involved in research, teaching and clinical work, and her interests lie in experimental neuropsychology, health psychology and clinical psychology. She has published a number of journal articles and book chapters and is a regular reviewer for a variety of journals. She first became interested in the issue of assessing driving ability in Parkinson's disease, after this issue arose for a number of her patients.