- Email: [email protected]
Parkinson's disease and issues related to driving
Parkinsonism and Related Disorders 15S3 (2009) S122–S125
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
Parkinson’s disease and issues related to driving Ryan J. Uitti* Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
article info
summary
Keywords: Parkinson’s disease Driving Motor vehicle safety
Driving a motor vehicle represents an important activity associated with personal independence and freedom. Being told that one can no longer drive is itself associated with loss of independence, depression, low self-esteem and reduced activities [1,2]. Patients with Parkinson’s disease (PD), therefore, understandably wish to continue to be able to maintain their ability to drive automobiles, motorcycles, airplanes, and boats, etc. The ability to determine if and when a PD patient is no longer fit to drive a motor vehicle is important for maintaining safety for the PD patient and the public. There are numerous requirements for being able to drive a motor vehicle safely. When any of these capacities deteriorate, the ability to drive safely may be lost. This review will concentrate upon common issues that would be peculiar to patients with PD. © 2009 Elsevier Ltd. All rights reserved.
1. Are PD drivers less safe than “general population” drivers? The majority of PD patients are able to drive safely. However, driving performance of PD patients collectively is worse than the general population. In a survey involving 5000 PD patients with driving licenses, 15% reported being involved in and 11% causing a crash in the preceding 5 years [3]. In those making mistakes, the most common errors consist of indecisiveness in T-junctions and reduced usage of mirrors (rear-view and side) [4]. Additionally, patients often do not recognize their inability to drive safely and many, despite being approved to drive by a neurologist, may be unsafe to drive according to an on-road assessment. One study reported that 35% of PD patients thought to be safe by a neurologist, were judged to be unsafe with on-road testing [5]. At the same time, a substantial number of PD patients recognize that they need to stop driving because of their progressive condition (perhaps at least 20%) [6]. More women typically give up driving than men [3]. In a referral center-based study, 20% of PD patients reported that they were no longer driving [7]. In this study, those with more severe motor PD (Hoehn and Yahr stage III) had five times more frequent MVAs than controls, while those with stage 1 had twice as many accidents. Cognitive deficits were also associated with greater danger in driving. A Mini-mental Status Examination score of 23 or less was associated with three times the risk for crashes. Utilizing a driving simulator, several small studies of PD patients and controls noted that PD patients, despite driving at a slower speed, had delayed deceleration, worse steering accuracy, slower reaction times and missed more red lights [8,9]. Additionally, in a * Correspondence: Ryan J. Uitti, M.D. Professor & Chair, Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32256, USA. Tel.: +1 904 953 7228 (3 8292). E-mail address: [email protected] (R.J. Uitti). 1353-8020/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.
study of 40 PD drivers, 27.5% were deemed unsafe drivers after evaluation by a team of experts conducting on-road, cognitive, visual and general clinical tests. 25% of these were found fit to drive with restriction and 2.5% unfit to drive [10]. In a study of PD patients and age-matched controls assessed by a driving instructor and occupational therapist, more than half of PD patients would not have passed a state driving test. More errors were made in changing/maintaining lanes, reversing, checking the blind spot, parking and at lighted intersections [11]. Similarly, almost half of PD drivers were found to be marginally safe or unsafe in another 25 patient study [12]. A large study (77 patients with mild-moderate PD) utilizing an instrumented vehicle (an actual car driving in real road conditions) concluded that PD drivers took longer to finish the route on a navigation task and made more incorrect turns, got lost, or committed safety errors than controls [13]. PD drivers also had more difficulty identifying specific landmarks and traffic signs [14]. Additionally, they had more errors due to distraction. 2. Reasons for declining safety in PD drivers Declining safety in PD drivers can occur on account of multiple factors. The most common contributors are cognitive decline and visual processing impairment, followed by motor dysfunction and other issues. 2.1. Cognitive decline Early dementia leads to confusion when driving in unfamiliar locations. Familiarity with roadways and traffic patterns may mitigate the need for quick decision-making that is often crucial when driving. The literature concerning safe driving in dementia patients is substantial [15] and germane to PD patients with
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
cognitive decline. The majority of PD patients who have stopped driving have a lower MMSE score than those currently driving or controls [6]. The method for driving also may change in PD drivers. In PD drivers the use of so-called “internal cues” (familiar vs. non-familiar environment) lessens, while external cues (providing warning signs vs. no signs) become more critical for PD patients [16]. While neuropsychological testing explains <70% of driving ability variance, it may correctly identify fitness to drive in >70% of patients [17]. These figures suggest that neuropsychological test results are important, but should not be sole determinants for fitness to drive evaluations. 2.2. Visual impairments Low visual contrast conditions (fog, etc.) represent a more dangerous environment for any driver. In a simulator study in which the driver’s approach to within 4 seconds of an intersection triggered the presence of another vehicle and potential crash, PD drivers had twice the risk for crashing as controls (when in the context of fog or low visibility [18]). Those PD drivers “crashing” also drove at an average speed that was 10 mph faster than controls. The time to first reaction was slower (by half a second) and correlated with worse scores of testing of visual perception and memory, visuospatial abilities, perception of structure from motion, visual speed of processing and attention, and visuospatial perception [19]. 2.3. Motor deficits Steering accuracy and reaction time are reduced in PD and usually [8] but not always [20], correlated with motor severity measured by Webster’s rating scale. It is important to note that even patients with significant postural instability and fall risk, are frequently quite functional, in terms of extremity movements, when seated (and in “driving position“). 2.4. Excessive daytime sleepiness Many drivers have experienced drowsiness while driving. In one sleep poll 57% of those interviewed said that they had driven while drowsy in the past year and 23% reported that they had actually fallen asleep at the wheel [21]) Many countries have reported similar experiences. In Norway 1 in 12 drivers reported that they had fallen asleep while driving during the past year, with 5% of these episodes resulting in a crash [22]. The United States National Highway Traffic Safety Administration estimates that 100,000 accidents and at least 1500 deaths per year can be attributed to driver drowsiness in the U.S. Drowsy driving crashes or fall-asleep crashes represent only 1–3% of policereported car crashes while fall-asleep crashes represent 6–10% of all self-reported car crashes. Interestingly, persons who fall asleep may not be good judges of how sleepy they are and how likely they are to fall asleep [23]. A prospective study of long-haul truck drivers determined that 10% entered stage 1 sleep while driving during a 2-week period. Prodromal drowsiness was documented by videotape and electrophysiological monitoring but not always appreciated by the subject [24]. Itoi has concluded that “people’s inability to judge sleep onset, and hence their susceptibility to sleeprelated accidents, may be attributable to a scarcity of meaningful physiological warning signs in some individuals and to a failure to acknowledge the importance of meaningful physiological warning signs in others” [25]. Dopamine agonists have been associated with a number of side effects in PD. Germane to this discussion is the potential to cause
S123
“sleep attacks” and motor vehicle accidents [26,27]. Dopaminergic “sleep attacks” may occur more frequently with dopamine agonists and are associated with incidence rates of 2–30%, with daytime somnolence rates of 3–57% [28]. PD patients with a history of sudden onset of sleep also probably make more errors in driving than those without sleepiness [29]. Excessive daytime sleepiness is quite common in PD (perhaps more than 50% of PD patients); large clinical trials report somnolence in 27% in even early PD patients treated with pramipexole [30] and 13% of patients treated with ropinirole [31]. Fortunately, the sudden onset of sleep is rare [32]. Clearly, while 11.2% of drivers report “sleep attacks,” only 0.5% of these admit these abnormalities or unpredictable [33]. Five studies indicate that 3–28% of PD drivers reported a sleep attack during driving, with 0–0.24% reporting an accident during the sleep attack [33]. Another study with 6620 PD patients indicated that 8% of those with a driver’s license reported having experienced a sleep attack while driving and overall, 2.2% of PD patients suffered an accident due to a sleep attack [3]. In perhaps the most informative study on the subject, Sanjiv et al reported a study employing Epworth Sleep Scale (ESS) and a modification of this same scale in PD patients receiving various medication regimens [34]. The ESS modification was that the same ESS questions were asked regarding the likelihood of falling asleep during various activities with the added qualification, “How likely would you be to fall asleep without warning (in a particular context)?” Their study reported daytime somnolence in 160 PD patients taking levodopa, or levodopa with one of three different dopamine agonists (bromocriptine, ropinirole, and pramipexole), with 40 patients in each treatment regimen. They concluded that all these medications, taken at usual daily doses, could contribute to daytime sleepiness. Importantly, “dozing off” also correlated highly with “falling asleep without warning,” as evidenced by the modified ESS correlating strongly with ESS. They suggested that the ESS could serve as a marker for the modified ESS and increasing risk for falling asleep while driving and potential MVA risk. In summary, data available to date suggests that (1) dopamine agonists and levodopa may increase somnolence, (2) no dopamine agonist is more likely than others to cause somnolence, (3) persons who fall asleep may not necessarily recall prodromal drowsiness, and (4) the risk for falling asleep while driving appears to be correlated with excessive daytime somnolence [35]. 3. Predictors of declining safety for PD drivers There are few studies systematically evaluating safety of PD patients when driving. Most studies suggest that overall, PD drivers are less safe than the general population. Declines in cognitive abilities (judgement, memory, and visuospatial skills), motor function (reaction time and coordination of movement), the ability to stay awake/alert, and a person’s perception of their own abilities are among the factors determining road safety. While declines in reaction time, motor speed, are obviously characteristic of parkinsonism, these do not contribute substantially to initial changes suggesting inability to safely operate a motor vehicle. Similarly, while falling asleep when driving is more common in PD, particularly in association with dopamine agonist therapy, this problem is a relatively rare cause of unsafe driving. The greatest contributors to unsafe driving are declines in visual sensory ability, motion perception and general cognition [36]. Declines in visual acuity, processing and attention also predict the total number of driving errors. Furthermore, weather may also contribute more substantially to road safety in PD drivers. Reduced visibility (from fog and low light conditions) preferentially exaggerates PD driver shortcomings compared to the general population. Restricted driving privileges may be most appropriate
S124
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
for patients who only do poorly in road safety tests under foggy/twilight conditions. Perception of visual-spatial processing, general cognitive and motor ability is also key. Most patients can correctly perceive that they are in a motor “on” state and can therefore choose to drive in this state. However, their ability to perceive shortcomings in cognitive and visuospatial sensory function is limited. Testing with standardized road safety simulators or appropriately instrumented vehicles, offers an excellent tool to determine potential ability to operate a motor vehicle safely. A study of over 150 consecutive PD drivers referred to a driving assessment center demonstrated that two-thirds were able to continue to driving, although 60% of these needed to use an automatic transmission or have other vehicle modifications [37]. When testing with a road safety simulator is not available, there are alternatives that can be employed. The first study published on this subject identified visual processing, levodopa use, and age as capable of explaining two-thirds of the variation of mistakes in driving tests [5]. Two of the greatest difficulty tasks for PD patients were driving in traffic and turning across traffic. Another study determined that three relatively simple tests predict driving safety: (1) Purdue Pegboard, (2) contrast sensitivity (Pelli-Robson test), and (3) cognition (verbal version of Symbol Digit Modalities test) [17]. Patients who passed and failed on the Pelli-Robson test scored 1.94 vs. 1.88, Symbol Digit Modalities scored 43.8 vs. 36.1 and Purdue Pegboard 32.0 vs. 26.8. This study also commented that adding disease duration provided even greater sensitivity and specificity, correctly being able to correctly classify 90% of patients into pass/fail driving safety status. Another study identified fitness to drive as being best predicted by 4 factors: (1) symptomatic disease duration, (2) contrast sensitivity, (3) Clinical Dementia Rating, and (4) motor part of the Unified Parkinson’s Disease Rating Scale [10]. While some PD patients should not drive at all, others may be able to drive safely with some restrictions (for example, familiar routes in clear weather conditions). In fact, many PD drivers modify their driving: reducing time driving, avoiding long routes, driving slower, avoiding night driving and heavy traffic and not driving alone [38]. Family members are typically able to accurately predict patient driving safety [4] undoubtedly because they may observe road safety. However, they are often reluctant to offer their observations because doing so may cause conflict within a family. Consequently, it may be useful to canvass family members for their opinions and rely on testing in an objective testing circumstance to make a determination whether a patient should continue driving. The reporting requirements for impaired and non-impaired PD drivers (and physician responsibility) vary substantially across the world. For example, in Australia, New Zealand and the United Kingdom, it is the driver’s responsibility to report his/her medical condition to the driver’s licensing authority. Patients are not required to report their illness to authorities in Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, Portugal, Spain, and Sweden. While in Austria, Denmark, Greece, Italy, Sweden, and some US states, physicians must report patient illnesses that may impair driving ability [39]. The American Academy of Neurology supports optional reporting of individuals with “medical conditions that may impact one’s ability to drive safely, especially in cases where public safety has already been compromised, or it is clear that the person no longer has the skills needed to drive safely.” [40] In summary, the ability for PD patients to drive safely can be predicted by virtue of disease duration, ability to visually process, and motor and cognitive function. Simulator and road-testing in selected PD drivers can result in recommending “to drive” (with and without restrictions) or “not drive” a motor vehicle. With progression of disease, aging, and changes in anti-parkinsonian
medication intake, ongoing deliberation is required to monitor fitness to drive in PD patients. Further research in this arena may help to direct driving deliberations more precisely and predictably. Conflict of interests No conflicts of interest. Funding Mayo Clinic Jacksonville is a Morris K. Udall Parkinson’s Disease Research Center of Excellence (NINDS P50 #NS40256) (RJU). RJU is also partially funded by Pacific Alzheimer Research Foundation (PARF) grant C06–01. References 1. Fonda SJ, Wallace RB, Herzog AR. Changes in driving patterns and worsening depressive symptoms among older adults. J Gerontol 2001;56:S343–51. 2. Marottoli RA, de Leon CFM, Glass TA, Williams CS, Cooney Jr LM, Berkman LF. Consequences of driving cessation: decreased out-of-home activity levels. J Gerontol 2000;55:S334–40. 3. Meindorfner C, Korner Y, Moller JC, Stiasny-Kolster K, Oertel WH, Kruger HP. Driving in Parkinson’s disease: mobility, accidents, and sudden onset of sleep at the wheel. Mov Disord 2005;20:832–42. 4. Cordell R, Lee HC, Granger A, Vieira B, Lee AH. Driving assessment in Parkinson’s disease – a novel predictor of performance? Mov Disord 2008;23:1217–22. 5. Heikkila VM, Turkka J, Korpelainen J, Kallanranta T, Summala H. Decreased driving ability in people with Parkinson’s disease. J Neurol Neurosurg Psychiatry 1998;64:325–30. 6. Zesiewicz TA, Cimino CR, Malek AR, Gardner N, Leaverton PL, Dunne PB, et al. Driving safety in Parkinson’s disease. Neurology 2002;59:1787–8. 7. Dubinsky R. Driving in Parkinson’s disease. Neurology 1991;41:517–20. 8. Madeley P, Hulley JL, Wildgust H, Mindham RH. Parkinson’s disease and driving ability. J Neurol Neurosurg Psychiatry 1990;53:580–2. 9. Stolwyk RJ, Triggs TJ, Charlton JL, Moss S, Iansek R, Bradshaw JL. Effect of a concurrent task on driving performance in people with Parkinson’s disease. Mov Disord 2006;21:2096–100. 10. Devos H, Vandenberghe W, Nieuwboer A, Tant M, Baten G, De Weerdt W. Predictors of fitness to drive in people with Parkinson disease. Neurology 2007;69:1434–41. 11. Wood JM, Worringham C, Kerr G, Mallon K, Silburn P. Quantitative assessment of driving performance in Parkinson’s disease. J Neurol Neurosurg Psychiatry 2005;76:176–80. 12. Amick MM, Grace J, Ott BR. Visual and cognitive predictors of driving safety in Parkinson’s disease patients. Arch Clin Neuropsychol 2007;22:957–67. 13. Uc EY, Rizzo M, Anderson SW, Sparks JD, Rodnitzky RL, Dawson JD. Impaired navigation in drivers with Parkinson’s disease. Brain 2007;130:2433–40. 14. Uc EY, Rizzo M, Anderson SW, Sparks J, Rodnitzky RL, Dawson JD. Impaired visual search in drivers with Parkinson’s disease. Ann Neurol 2006;60:407–13. 15. Uc EY, Rizzo M. Driving and neurodegenerative diseases. Curr Neurol Neurosci Rep 2008;8:377–83. 16. Stolwyk RJ, Triggs TJ, Charlton JL, Iansek R, Bradshaw JL. Impact of internal versus external cueing on driving performance in people with Parkinson’s disease. Mov Disord 2005;20:846–57. 17. Worringham CJ, Wood JM, Kerr GK, Silburn PA. Predictors of driving assessment outcome in Parkinson’s disease. Mov Disord 2006;21:230–5. 18. Uc E. Driving under low contrast visibility conditions in Parkinson’s disease. Neurology 2009. 19. Uc E. Increased crash risk in drivers with Parkinson’s disease under low visual contrast lighting conditions. Neurology 2007;68:A208. 20. Lings S, Dupont E. Driving with Parkinson’s disease: A controlled laboratory investigation. Acta Neurol Scand 1991;86:33–9. 21. Johnson E. Omnibus Sleep in America Poll. Washington, D.C.: National Sleep Foundation; 1998. 22. Sagberg F. Road accidents caused by drivers falling asleep. Accid Anal Prevent 1999;31:639–49. 23. United States Federal Highway Administration. The driver fatigue and alertness study: a success story of partnerships, data and analysis. Washington, D.C.: Federal Highway Administration; 1997. 24. Mitler MM, Miller JC, Lipsitz JJ, Walsh JK, Wylie CD. The sleep of long-haul truck drivers. N Engl J Med 1997;337:755–61. 25. Itoi A, AAA Foundation for Traffic Safety. Can drivers avoid falling asleep at the wheel?: relationship between awareness of sleepiness and ability to predict sleep onset. Washington, D.C.: AAA Foundation for Traffic Safety; 1993. 26. Frucht S, Rogers JD, Greene PE, Gordon MF, Fahn S. Falling asleep at the wheel: motor vehicle mishaps in persons taking pramipexole and ropinirole. Neurology 1999;52:1908–10.
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
27. Comella CL. Sleep disorders in Parkinson’s disease: an overview. Mov Disord 2007;22(Suppl 17):S367–73. 28. Homann CN, Suppan K, Homann B, Crevenna R, Ivanic G, Ruzicka E. Driving in Parkinson’s disease – a health hazard? J Neurol 2003;250:1439–46. 29. Moller JC, Stiasny K, Hargutt V, Cassel W, Tietze H, Peter JH, et al. Evaluation of sleep and driving performance in six patients with Parkinson’s disease reporting sudden onset of sleep under dopaminergic medication: a pilot study. Mov Disord 2002;17:474–81. 30. Parkinson Study Group. Safety and efficacy of pramipexole in early Parkinson disease. A randomized dose-ranging study. JAMA 1997;278:125–30. 31. Sethi KD, O’Brien CF, Hammerstad JP, Adler CH, Davis TL, Taylor RL, et al. Ropinirole for the treatment of early Parkinson disease: a 12-month experience. Ropinirole Study Group. Arch Neurol 1998;55:1211–6. 32. Hobson DE, Lang AE, Martin WR, Razmy A, Rivest J, Fleming J. Excessive daytime sleepiness and sudden-onset sleep in Parkinson disease: a survey by the Canadian Movement Disorders Group. JAMA 2002;287:455–63. 33. Kulisevsky J. Acute effects of levodopa on neuropsychological performance in stable and fluctuating Parkinson’s disease patients at different levodopa plasma levels. Brain 1996;119:2121–32.
S125
34. Sanjiv CC, Schulzer M, Mak E, Fleming J, Martin WR, Brown T, et al. Daytime somnolence in patients with Parkinson’s disease. Parkinsonism Relat Disord 2001;7:283–86. 35. Uitti RJ, Wszolek ZK. Dopamine agonists, sleep disorders, and driving in Parkinson’s disease. Adv Neurol 2003;91:343–9. 36. Uc EY, Rizzo M, Anderson SW, Sparks JD, Rodnitzky RL, Dawson JD. Driving with distraction in Parkinson disease. Neurology 2006;67:1774–80. 37. Singh R, Pentland B, Hunter J, Provan F. Parkinson’s disease and driving ability. J Neurol Neurosurg Psychiatry 2007;78:363–6. 38. Adler G. The older driver with Parkinson’s disease. J Gerontol Social Work 2000; 34:39–49. 39. Klimkeit EI, Bradshaw JL, Charlton J, Stolwyk R, Georgiou-Karistianis N. Driving ability in Parkinson’s disease: current status of research. Neurosci Biobehav Rev 2009;33:223–31. 40. Bacon D, Fisher RS, Morris JC, Rizzo M, Spanaki MV. American Academy of Neurology position statement on physician reporting of medical conditions that may affect driving competence. Neurology 2007;68:1174–7.
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
Parkinson’s disease and issues related to driving Ryan J. Uitti* Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
article info
summary
Keywords: Parkinson’s disease Driving Motor vehicle safety
Driving a motor vehicle represents an important activity associated with personal independence and freedom. Being told that one can no longer drive is itself associated with loss of independence, depression, low self-esteem and reduced activities [1,2]. Patients with Parkinson’s disease (PD), therefore, understandably wish to continue to be able to maintain their ability to drive automobiles, motorcycles, airplanes, and boats, etc. The ability to determine if and when a PD patient is no longer fit to drive a motor vehicle is important for maintaining safety for the PD patient and the public. There are numerous requirements for being able to drive a motor vehicle safely. When any of these capacities deteriorate, the ability to drive safely may be lost. This review will concentrate upon common issues that would be peculiar to patients with PD. © 2009 Elsevier Ltd. All rights reserved.
1. Are PD drivers less safe than “general population” drivers? The majority of PD patients are able to drive safely. However, driving performance of PD patients collectively is worse than the general population. In a survey involving 5000 PD patients with driving licenses, 15% reported being involved in and 11% causing a crash in the preceding 5 years [3]. In those making mistakes, the most common errors consist of indecisiveness in T-junctions and reduced usage of mirrors (rear-view and side) [4]. Additionally, patients often do not recognize their inability to drive safely and many, despite being approved to drive by a neurologist, may be unsafe to drive according to an on-road assessment. One study reported that 35% of PD patients thought to be safe by a neurologist, were judged to be unsafe with on-road testing [5]. At the same time, a substantial number of PD patients recognize that they need to stop driving because of their progressive condition (perhaps at least 20%) [6]. More women typically give up driving than men [3]. In a referral center-based study, 20% of PD patients reported that they were no longer driving [7]. In this study, those with more severe motor PD (Hoehn and Yahr stage III) had five times more frequent MVAs than controls, while those with stage 1 had twice as many accidents. Cognitive deficits were also associated with greater danger in driving. A Mini-mental Status Examination score of 23 or less was associated with three times the risk for crashes. Utilizing a driving simulator, several small studies of PD patients and controls noted that PD patients, despite driving at a slower speed, had delayed deceleration, worse steering accuracy, slower reaction times and missed more red lights [8,9]. Additionally, in a * Correspondence: Ryan J. Uitti, M.D. Professor & Chair, Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32256, USA. Tel.: +1 904 953 7228 (3 8292). E-mail address: [email protected] (R.J. Uitti). 1353-8020/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.
study of 40 PD drivers, 27.5% were deemed unsafe drivers after evaluation by a team of experts conducting on-road, cognitive, visual and general clinical tests. 25% of these were found fit to drive with restriction and 2.5% unfit to drive [10]. In a study of PD patients and age-matched controls assessed by a driving instructor and occupational therapist, more than half of PD patients would not have passed a state driving test. More errors were made in changing/maintaining lanes, reversing, checking the blind spot, parking and at lighted intersections [11]. Similarly, almost half of PD drivers were found to be marginally safe or unsafe in another 25 patient study [12]. A large study (77 patients with mild-moderate PD) utilizing an instrumented vehicle (an actual car driving in real road conditions) concluded that PD drivers took longer to finish the route on a navigation task and made more incorrect turns, got lost, or committed safety errors than controls [13]. PD drivers also had more difficulty identifying specific landmarks and traffic signs [14]. Additionally, they had more errors due to distraction. 2. Reasons for declining safety in PD drivers Declining safety in PD drivers can occur on account of multiple factors. The most common contributors are cognitive decline and visual processing impairment, followed by motor dysfunction and other issues. 2.1. Cognitive decline Early dementia leads to confusion when driving in unfamiliar locations. Familiarity with roadways and traffic patterns may mitigate the need for quick decision-making that is often crucial when driving. The literature concerning safe driving in dementia patients is substantial [15] and germane to PD patients with
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
cognitive decline. The majority of PD patients who have stopped driving have a lower MMSE score than those currently driving or controls [6]. The method for driving also may change in PD drivers. In PD drivers the use of so-called “internal cues” (familiar vs. non-familiar environment) lessens, while external cues (providing warning signs vs. no signs) become more critical for PD patients [16]. While neuropsychological testing explains <70% of driving ability variance, it may correctly identify fitness to drive in >70% of patients [17]. These figures suggest that neuropsychological test results are important, but should not be sole determinants for fitness to drive evaluations. 2.2. Visual impairments Low visual contrast conditions (fog, etc.) represent a more dangerous environment for any driver. In a simulator study in which the driver’s approach to within 4 seconds of an intersection triggered the presence of another vehicle and potential crash, PD drivers had twice the risk for crashing as controls (when in the context of fog or low visibility [18]). Those PD drivers “crashing” also drove at an average speed that was 10 mph faster than controls. The time to first reaction was slower (by half a second) and correlated with worse scores of testing of visual perception and memory, visuospatial abilities, perception of structure from motion, visual speed of processing and attention, and visuospatial perception [19]. 2.3. Motor deficits Steering accuracy and reaction time are reduced in PD and usually [8] but not always [20], correlated with motor severity measured by Webster’s rating scale. It is important to note that even patients with significant postural instability and fall risk, are frequently quite functional, in terms of extremity movements, when seated (and in “driving position“). 2.4. Excessive daytime sleepiness Many drivers have experienced drowsiness while driving. In one sleep poll 57% of those interviewed said that they had driven while drowsy in the past year and 23% reported that they had actually fallen asleep at the wheel [21]) Many countries have reported similar experiences. In Norway 1 in 12 drivers reported that they had fallen asleep while driving during the past year, with 5% of these episodes resulting in a crash [22]. The United States National Highway Traffic Safety Administration estimates that 100,000 accidents and at least 1500 deaths per year can be attributed to driver drowsiness in the U.S. Drowsy driving crashes or fall-asleep crashes represent only 1–3% of policereported car crashes while fall-asleep crashes represent 6–10% of all self-reported car crashes. Interestingly, persons who fall asleep may not be good judges of how sleepy they are and how likely they are to fall asleep [23]. A prospective study of long-haul truck drivers determined that 10% entered stage 1 sleep while driving during a 2-week period. Prodromal drowsiness was documented by videotape and electrophysiological monitoring but not always appreciated by the subject [24]. Itoi has concluded that “people’s inability to judge sleep onset, and hence their susceptibility to sleeprelated accidents, may be attributable to a scarcity of meaningful physiological warning signs in some individuals and to a failure to acknowledge the importance of meaningful physiological warning signs in others” [25]. Dopamine agonists have been associated with a number of side effects in PD. Germane to this discussion is the potential to cause
S123
“sleep attacks” and motor vehicle accidents [26,27]. Dopaminergic “sleep attacks” may occur more frequently with dopamine agonists and are associated with incidence rates of 2–30%, with daytime somnolence rates of 3–57% [28]. PD patients with a history of sudden onset of sleep also probably make more errors in driving than those without sleepiness [29]. Excessive daytime sleepiness is quite common in PD (perhaps more than 50% of PD patients); large clinical trials report somnolence in 27% in even early PD patients treated with pramipexole [30] and 13% of patients treated with ropinirole [31]. Fortunately, the sudden onset of sleep is rare [32]. Clearly, while 11.2% of drivers report “sleep attacks,” only 0.5% of these admit these abnormalities or unpredictable [33]. Five studies indicate that 3–28% of PD drivers reported a sleep attack during driving, with 0–0.24% reporting an accident during the sleep attack [33]. Another study with 6620 PD patients indicated that 8% of those with a driver’s license reported having experienced a sleep attack while driving and overall, 2.2% of PD patients suffered an accident due to a sleep attack [3]. In perhaps the most informative study on the subject, Sanjiv et al reported a study employing Epworth Sleep Scale (ESS) and a modification of this same scale in PD patients receiving various medication regimens [34]. The ESS modification was that the same ESS questions were asked regarding the likelihood of falling asleep during various activities with the added qualification, “How likely would you be to fall asleep without warning (in a particular context)?” Their study reported daytime somnolence in 160 PD patients taking levodopa, or levodopa with one of three different dopamine agonists (bromocriptine, ropinirole, and pramipexole), with 40 patients in each treatment regimen. They concluded that all these medications, taken at usual daily doses, could contribute to daytime sleepiness. Importantly, “dozing off” also correlated highly with “falling asleep without warning,” as evidenced by the modified ESS correlating strongly with ESS. They suggested that the ESS could serve as a marker for the modified ESS and increasing risk for falling asleep while driving and potential MVA risk. In summary, data available to date suggests that (1) dopamine agonists and levodopa may increase somnolence, (2) no dopamine agonist is more likely than others to cause somnolence, (3) persons who fall asleep may not necessarily recall prodromal drowsiness, and (4) the risk for falling asleep while driving appears to be correlated with excessive daytime somnolence [35]. 3. Predictors of declining safety for PD drivers There are few studies systematically evaluating safety of PD patients when driving. Most studies suggest that overall, PD drivers are less safe than the general population. Declines in cognitive abilities (judgement, memory, and visuospatial skills), motor function (reaction time and coordination of movement), the ability to stay awake/alert, and a person’s perception of their own abilities are among the factors determining road safety. While declines in reaction time, motor speed, are obviously characteristic of parkinsonism, these do not contribute substantially to initial changes suggesting inability to safely operate a motor vehicle. Similarly, while falling asleep when driving is more common in PD, particularly in association with dopamine agonist therapy, this problem is a relatively rare cause of unsafe driving. The greatest contributors to unsafe driving are declines in visual sensory ability, motion perception and general cognition [36]. Declines in visual acuity, processing and attention also predict the total number of driving errors. Furthermore, weather may also contribute more substantially to road safety in PD drivers. Reduced visibility (from fog and low light conditions) preferentially exaggerates PD driver shortcomings compared to the general population. Restricted driving privileges may be most appropriate
S124
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
for patients who only do poorly in road safety tests under foggy/twilight conditions. Perception of visual-spatial processing, general cognitive and motor ability is also key. Most patients can correctly perceive that they are in a motor “on” state and can therefore choose to drive in this state. However, their ability to perceive shortcomings in cognitive and visuospatial sensory function is limited. Testing with standardized road safety simulators or appropriately instrumented vehicles, offers an excellent tool to determine potential ability to operate a motor vehicle safely. A study of over 150 consecutive PD drivers referred to a driving assessment center demonstrated that two-thirds were able to continue to driving, although 60% of these needed to use an automatic transmission or have other vehicle modifications [37]. When testing with a road safety simulator is not available, there are alternatives that can be employed. The first study published on this subject identified visual processing, levodopa use, and age as capable of explaining two-thirds of the variation of mistakes in driving tests [5]. Two of the greatest difficulty tasks for PD patients were driving in traffic and turning across traffic. Another study determined that three relatively simple tests predict driving safety: (1) Purdue Pegboard, (2) contrast sensitivity (Pelli-Robson test), and (3) cognition (verbal version of Symbol Digit Modalities test) [17]. Patients who passed and failed on the Pelli-Robson test scored 1.94 vs. 1.88, Symbol Digit Modalities scored 43.8 vs. 36.1 and Purdue Pegboard 32.0 vs. 26.8. This study also commented that adding disease duration provided even greater sensitivity and specificity, correctly being able to correctly classify 90% of patients into pass/fail driving safety status. Another study identified fitness to drive as being best predicted by 4 factors: (1) symptomatic disease duration, (2) contrast sensitivity, (3) Clinical Dementia Rating, and (4) motor part of the Unified Parkinson’s Disease Rating Scale [10]. While some PD patients should not drive at all, others may be able to drive safely with some restrictions (for example, familiar routes in clear weather conditions). In fact, many PD drivers modify their driving: reducing time driving, avoiding long routes, driving slower, avoiding night driving and heavy traffic and not driving alone [38]. Family members are typically able to accurately predict patient driving safety [4] undoubtedly because they may observe road safety. However, they are often reluctant to offer their observations because doing so may cause conflict within a family. Consequently, it may be useful to canvass family members for their opinions and rely on testing in an objective testing circumstance to make a determination whether a patient should continue driving. The reporting requirements for impaired and non-impaired PD drivers (and physician responsibility) vary substantially across the world. For example, in Australia, New Zealand and the United Kingdom, it is the driver’s responsibility to report his/her medical condition to the driver’s licensing authority. Patients are not required to report their illness to authorities in Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, Portugal, Spain, and Sweden. While in Austria, Denmark, Greece, Italy, Sweden, and some US states, physicians must report patient illnesses that may impair driving ability [39]. The American Academy of Neurology supports optional reporting of individuals with “medical conditions that may impact one’s ability to drive safely, especially in cases where public safety has already been compromised, or it is clear that the person no longer has the skills needed to drive safely.” [40] In summary, the ability for PD patients to drive safely can be predicted by virtue of disease duration, ability to visually process, and motor and cognitive function. Simulator and road-testing in selected PD drivers can result in recommending “to drive” (with and without restrictions) or “not drive” a motor vehicle. With progression of disease, aging, and changes in anti-parkinsonian
medication intake, ongoing deliberation is required to monitor fitness to drive in PD patients. Further research in this arena may help to direct driving deliberations more precisely and predictably. Conflict of interests No conflicts of interest. Funding Mayo Clinic Jacksonville is a Morris K. Udall Parkinson’s Disease Research Center of Excellence (NINDS P50 #NS40256) (RJU). RJU is also partially funded by Pacific Alzheimer Research Foundation (PARF) grant C06–01. References 1. Fonda SJ, Wallace RB, Herzog AR. Changes in driving patterns and worsening depressive symptoms among older adults. J Gerontol 2001;56:S343–51. 2. Marottoli RA, de Leon CFM, Glass TA, Williams CS, Cooney Jr LM, Berkman LF. Consequences of driving cessation: decreased out-of-home activity levels. J Gerontol 2000;55:S334–40. 3. Meindorfner C, Korner Y, Moller JC, Stiasny-Kolster K, Oertel WH, Kruger HP. Driving in Parkinson’s disease: mobility, accidents, and sudden onset of sleep at the wheel. Mov Disord 2005;20:832–42. 4. Cordell R, Lee HC, Granger A, Vieira B, Lee AH. Driving assessment in Parkinson’s disease – a novel predictor of performance? Mov Disord 2008;23:1217–22. 5. Heikkila VM, Turkka J, Korpelainen J, Kallanranta T, Summala H. Decreased driving ability in people with Parkinson’s disease. J Neurol Neurosurg Psychiatry 1998;64:325–30. 6. Zesiewicz TA, Cimino CR, Malek AR, Gardner N, Leaverton PL, Dunne PB, et al. Driving safety in Parkinson’s disease. Neurology 2002;59:1787–8. 7. Dubinsky R. Driving in Parkinson’s disease. Neurology 1991;41:517–20. 8. Madeley P, Hulley JL, Wildgust H, Mindham RH. Parkinson’s disease and driving ability. J Neurol Neurosurg Psychiatry 1990;53:580–2. 9. Stolwyk RJ, Triggs TJ, Charlton JL, Moss S, Iansek R, Bradshaw JL. Effect of a concurrent task on driving performance in people with Parkinson’s disease. Mov Disord 2006;21:2096–100. 10. Devos H, Vandenberghe W, Nieuwboer A, Tant M, Baten G, De Weerdt W. Predictors of fitness to drive in people with Parkinson disease. Neurology 2007;69:1434–41. 11. Wood JM, Worringham C, Kerr G, Mallon K, Silburn P. Quantitative assessment of driving performance in Parkinson’s disease. J Neurol Neurosurg Psychiatry 2005;76:176–80. 12. Amick MM, Grace J, Ott BR. Visual and cognitive predictors of driving safety in Parkinson’s disease patients. Arch Clin Neuropsychol 2007;22:957–67. 13. Uc EY, Rizzo M, Anderson SW, Sparks JD, Rodnitzky RL, Dawson JD. Impaired navigation in drivers with Parkinson’s disease. Brain 2007;130:2433–40. 14. Uc EY, Rizzo M, Anderson SW, Sparks J, Rodnitzky RL, Dawson JD. Impaired visual search in drivers with Parkinson’s disease. Ann Neurol 2006;60:407–13. 15. Uc EY, Rizzo M. Driving and neurodegenerative diseases. Curr Neurol Neurosci Rep 2008;8:377–83. 16. Stolwyk RJ, Triggs TJ, Charlton JL, Iansek R, Bradshaw JL. Impact of internal versus external cueing on driving performance in people with Parkinson’s disease. Mov Disord 2005;20:846–57. 17. Worringham CJ, Wood JM, Kerr GK, Silburn PA. Predictors of driving assessment outcome in Parkinson’s disease. Mov Disord 2006;21:230–5. 18. Uc E. Driving under low contrast visibility conditions in Parkinson’s disease. Neurology 2009. 19. Uc E. Increased crash risk in drivers with Parkinson’s disease under low visual contrast lighting conditions. Neurology 2007;68:A208. 20. Lings S, Dupont E. Driving with Parkinson’s disease: A controlled laboratory investigation. Acta Neurol Scand 1991;86:33–9. 21. Johnson E. Omnibus Sleep in America Poll. Washington, D.C.: National Sleep Foundation; 1998. 22. Sagberg F. Road accidents caused by drivers falling asleep. Accid Anal Prevent 1999;31:639–49. 23. United States Federal Highway Administration. The driver fatigue and alertness study: a success story of partnerships, data and analysis. Washington, D.C.: Federal Highway Administration; 1997. 24. Mitler MM, Miller JC, Lipsitz JJ, Walsh JK, Wylie CD. The sleep of long-haul truck drivers. N Engl J Med 1997;337:755–61. 25. Itoi A, AAA Foundation for Traffic Safety. Can drivers avoid falling asleep at the wheel?: relationship between awareness of sleepiness and ability to predict sleep onset. Washington, D.C.: AAA Foundation for Traffic Safety; 1993. 26. Frucht S, Rogers JD, Greene PE, Gordon MF, Fahn S. Falling asleep at the wheel: motor vehicle mishaps in persons taking pramipexole and ropinirole. Neurology 1999;52:1908–10.
R.J. Uitti / Parkinsonism and Related Disorders 15S3 (2009) S122–S125
27. Comella CL. Sleep disorders in Parkinson’s disease: an overview. Mov Disord 2007;22(Suppl 17):S367–73. 28. Homann CN, Suppan K, Homann B, Crevenna R, Ivanic G, Ruzicka E. Driving in Parkinson’s disease – a health hazard? J Neurol 2003;250:1439–46. 29. Moller JC, Stiasny K, Hargutt V, Cassel W, Tietze H, Peter JH, et al. Evaluation of sleep and driving performance in six patients with Parkinson’s disease reporting sudden onset of sleep under dopaminergic medication: a pilot study. Mov Disord 2002;17:474–81. 30. Parkinson Study Group. Safety and efficacy of pramipexole in early Parkinson disease. A randomized dose-ranging study. JAMA 1997;278:125–30. 31. Sethi KD, O’Brien CF, Hammerstad JP, Adler CH, Davis TL, Taylor RL, et al. Ropinirole for the treatment of early Parkinson disease: a 12-month experience. Ropinirole Study Group. Arch Neurol 1998;55:1211–6. 32. Hobson DE, Lang AE, Martin WR, Razmy A, Rivest J, Fleming J. Excessive daytime sleepiness and sudden-onset sleep in Parkinson disease: a survey by the Canadian Movement Disorders Group. JAMA 2002;287:455–63. 33. Kulisevsky J. Acute effects of levodopa on neuropsychological performance in stable and fluctuating Parkinson’s disease patients at different levodopa plasma levels. Brain 1996;119:2121–32.
S125
34. Sanjiv CC, Schulzer M, Mak E, Fleming J, Martin WR, Brown T, et al. Daytime somnolence in patients with Parkinson’s disease. Parkinsonism Relat Disord 2001;7:283–86. 35. Uitti RJ, Wszolek ZK. Dopamine agonists, sleep disorders, and driving in Parkinson’s disease. Adv Neurol 2003;91:343–9. 36. Uc EY, Rizzo M, Anderson SW, Sparks JD, Rodnitzky RL, Dawson JD. Driving with distraction in Parkinson disease. Neurology 2006;67:1774–80. 37. Singh R, Pentland B, Hunter J, Provan F. Parkinson’s disease and driving ability. J Neurol Neurosurg Psychiatry 2007;78:363–6. 38. Adler G. The older driver with Parkinson’s disease. J Gerontol Social Work 2000; 34:39–49. 39. Klimkeit EI, Bradshaw JL, Charlton J, Stolwyk R, Georgiou-Karistianis N. Driving ability in Parkinson’s disease: current status of research. Neurosci Biobehav Rev 2009;33:223–31. 40. Bacon D, Fisher RS, Morris JC, Rizzo M, Spanaki MV. American Academy of Neurology position statement on physician reporting of medical conditions that may affect driving competence. Neurology 2007;68:1174–7.