Parkinson & Movement Disorder Alliance offered a webinar in early November on driving and road safety with Parkinson’s disease (PD). The speaker was Dr. Ergun Uc, a professor of neurology at the University of Iowa and movement disorder specialist with the Iowa City Veteran Affairs. He discussed research into how PD has affected their driving, and ways to make sure drivers with PD can be safe on the road.
Dr. Uc demonstrated how to measure driving abilities in normal elderly people versus people with Parkinson’s disease. Methods used to measure driving abilities in normal, elderly people versus people with PD include a vehicle hooked up to instruments, an MRI or PET scan taken during a driving simulation, and past data of car crashes. Dr. Uc found that while age or diagnosis is not enough to decide if someone is fit to drive, people with PD are 25% more likely to get into a crash or experience a near miss.
However, as people age and their Parkinson’s symptoms worsen, they are more likely to stop driving entirely. It is important to look for the indicators that might suggest someone is no longer capable of driving, such as visual or cognitive decline.
The webinar was recorded and can be viewed here on the PMD Alliance YouTube channel here.
Stanford Parkinson’s Community Outreach has a lot of resources on driving with PD here.
I listened to this presentation and am sharing a summary of the talk below.
– August Besser
“Driving and Road Safety for People with PD” – Lecture Notes
Speaker: Dr. Ergun Uc, movement disorder specialist, Iowa City Veteran Affairs
Webinar Host: Parkinson & Movement Disorder Alliance
November 6, 2020
Summary by August Besser, Stanford Parkinson’s Community Outreach
Relevance of Driving
- Enables independence and community mobility
- Supports a sense of identity and competence
- Perceived stigma of losing license
- Worry for burden to loved ones
- Important for maintaining quality of life
Case 1: 55-year-old man with PD for 4 years, working full time, did not complain of any driving issues, but is concerned about excessive daytime sleepiness. His only motor concern is intermittent resting tremor in the left hand, with no balance or gait problems. He is on ropinirole 6 mg TID.
Case 2: 76-year-old woman has had postural instability-gait disorder predominant parkinsonism for 4 years with mild responsiveness to levodopa. She restricted driving to daytime in her local small town in accordance with her family’s wishes after some near-misses at night and in congested traffic.
Case 3: 62-year-old man with PD for 8 years, has moderate wearing off and peak dose dyskinesias on levodopa.
Information processing during driving
- Perceive, attend, interpret
- Plan response
- Execute action
Behavior: slow down/stop
Neural Substrates of Driving
A functional MRI or PET scan during simulated driving showed that the areas responsible for visuospatial perception, visuomotor coordination, and executive functions are activated during the simulation
Many Brain Systems are Involved in PD
- Cognitive: mild impairment, dementia
- Lost chemicals: dopamine, norepinephrine, serotonin, acetylcholine
How to Study Driving?
Off road measures: demographics, driving habits, vision, cognition, motor function
Real life: crashes, citations, driving cessation
Simulation: crashes and vehicle control data
Road test: instrumented vehicle – pass/fail, error counts, task performance, vehicle control data
Off-Road Battery Test
Visual sensory: near/far visual activity, contrast sensitivity, structure from motion
Visual processing speed/attention: useful field of view
Visuospatial: complex figure test (copy), judgement of line orientation, block design test
Visual memory: complex figure test (recall), Benton visual retention test
Executive functions: trail making (B-A), controlled oral word association
Verbal memory: auditory verbal learning test (COGSAT composite score)
Motor: unified PD rating scale, functional reach, finger tapping, 7-meter walk
Comparison: Off-Road Measures
- ~100 PD patients vs 150 healthy elderly (licensed, experienced, active drivers with no confounding medical, visual, or psychiatric conditions)
- PD age 678 years (similar to controls), duration 65 years
- Ambulatory, not demented
- Tested during ON (when medications are working)
- Compared to controls, mild-moderate deficits in: motor function, vision, cognition, mood, and sleepiness
Driving History and Habits
Compared to controls, people with PD:
- Drove slower, fewer days
- Avoided rush hour and busy roads
- Preferred another driver
- Rated themselves poorer
- Received suggestion to stop driving
Higher “risk lowering score” correlated with higher PD stage and lower cognition, vision, driving exposure, and self-rating.
Mechanisms of Driving Impairment in PD
- Reduced information processing at all levels (visual, spatial, executive, motor, memory, executive) leads to either no reaction or a late reaction, which them leads to a crash
- Driving simulator: increased reaction time and increased crash risk in PD
Visibility and Vehicle Control in Simulator
- Both PD and healthy groups drove during high and low visibility in the same setting (road segments)
- Healthy people drove normal in high visibility (clear sky) and low visibility (fog)
- People with PD drove abnormally in high visibility and very abnormally in low visibility
- Vehicle control was determined by: weaving, number of lane violations
Effect of Distraction on Driving
- Driving alone vs driving with distractions
- Driving performance measures: lane violations and deviation from ideal path
- Listening to simple sentences: 37% decrease in visuospatial activation
- Increased lane violations and weaving
Road Safety in PD
- Highly significant results: more road error counts in PD drivers than control (25% more PD drivers had errors than control drivers)
- Familiarity with roads diminished “serious” errors in PD compared to controls
- Significant predictors of safer drivers: far visual acuity and useful field of view
- Two years later: PD returnees had poorer cognitive function than control returnees at baseline
Failure on the Road Test in PD
- 0 to 24% of control drivers failed their road test, whereas 30 to 56% of PD drivers failed their road test
- Road predictors of fail: lateral positioning at low speed, speed adaptations at high speed, left turning at intersections
- Clinical predictors of fail: older age, postural instability/gait disorder, impaired visual acuity/scanning abnormal useful field of view
Prospective Real-World Performance
- Crashes: there was no change in crashes over several years because the PD patients who would have crashed stopped driving
Course of Parkinson’s disease
- Driving impairment starts in prodromal state
- First, there is difficulty driving at night
- Then, there is difficulty in performing dual tasks
- Next, the PD patient ends up getting lost
- Lastly, there might be a crash or a near-miss
Case Scenarios Revisited
Case 1: 55-year-old man with PD for 4 years, working full time, did not complain of any driving issues, but is concerned about excessive daytime sleepiness. His only motor concern is intermittent resting tremor in the left hand, with no balance or gait problems. He is on ropinirole 6 mg TID. He has very mild executive dysfunction and slight decrease in visual contrast sensitivity. Decrease or replace ropinirole, continue driving w/o restrictions.
Case 2: 76-year-old woman has had postural instability-gait disorder predominant parkinsonism for 4 years with mild responsiveness to levodopa. She restricted driving to daytime in her local small town in accordance with her family’s wishes after some near-misses at night and in congested traffic. She has executive, visuospatial, and memory dysfunction consistent with dementia. Her visual contrast sensitivity and useful field of view are markedly abnormal. Stop driving!
Case 3: 62-year-old man with PD for 8 years, has moderate wearing off and peak dose dyskinesias on levodopa. He has mild executive and visuospatial impairment with moderate decrease in visual contrast sensitivity and useful field of view. Road test, repeat annually if he passes.
Fitness to Drive
“Guidelines developed by the National Highway Traffic Safety Administration and Federal Motor Carrier Safety Administration suggest a case by case, multidisciplinary evaluation of the patient due to the highly individualized nature of the disease and variable progression.”
Fitness to Drive: Practical Approach in the Clinic
- Concerns by the patient or family or referring provider
- Bedside impression on cognition, mobility, vision
- Neuropsychological testing vision testing. If unsure but find the patient safe enough for road test, send the patient to DOT for road test. If clearly impaired, recommend driving cessation.
Reporting Medically-Impaired Drivers
- Not uniform across USA and across the world
- Need to know local rules and regulations on reporting
- Age or diagnosis is not enough to decide on fitness to drive
- Experimental driving performance: worse both on road and in simulator, steeper decline
- Dual tasks: worsen driving performance (particularly in those with limited cognitive reserves
- Real life: higher risk of driving cessation in PD, no conclusive evidence linking PD to increased crashes
- Predictors: depends on demands – impaired vision, cognition (executive, visuospatial), motor dysfunction (sudden hazards, driving cessation), familiarity with roads and compensation strategies may help
- Rehabilitation: train driving vs underlying abilities
How do you feel about people listening to music while they’re driving, especially if it helps them stay awake?
I think for the most part, people should not have distractions while driving. That being said, I have had times where I am driving and start to feel drowsy, so I put on some music to help me stay awake, as well as opening up the windows to get some fresh air. I am a fan of Queen, so I prefer to listen to them when I need to stay awake. Just make sure to minimize or eliminate other distractions to focus on your driving.
Have you heard of Drive Able? It’s a computerized driving test offered by Drive Able that measures visuospatial, reaction speed, and executive function through a program called DCAT.
I have heard of Drive Able, but I have not studied the DCAT program in particular. All of these kinds of programs measure the same kinds of responses, they just use different names for the tests. If there is credible scientific research published and the right kinds of authorities support the test, then I would trust it. However, there are many other holistic things to measure when it comes to Parkinson’s disease and the ability to drive. First, is the family comfortable with the patient driving? Is the patient able to remember where they are going? How is their driving: are they swerving, are they driving unreasonably slower, are they distracted? It’s hard to know if someone is capable of driving just from one test.
Someone here in the comments wrote how they took their husband to see 3 neuropsychiatrists to determine if their husband still had his executive function, and all of the tests were inconclusive. She wanted to know where to find a driving simulation test, since there wasn’t one close to her. Should she try to find a driving instructor?
Let me first comment on driving simulators, because they can vary from a desktop application to a $40 million facility where you have all the bells and whistles. Here at the University of Iowa, we are home to the National Advanced Driving Simulator. Driving simulators are not 100% real because there is no risk to life or limb. Similarly, a DOT test with an instructor is not 100% real either because the state driving test is geared towards novice drivers to see if they know the rules of the road and to get their driver’s license. They don’t necessarily measure reactions like in a simulator. All of these measures have their advantages and disadvantages, so should not look at them as fully predictive. Using an occupational therapist who is certified in driving evaluation would be the best choice because they have both the clinical acumen as well as the technical approach.
Is freezing an issue when driving?
It could be. Freezing typically occurs during gait, so if this person has an unpredictable off-period and their off-period affects cognitive function, then it could be a problem. In our studies, we chose Parkinson’s patients who had milder off-periods so that was not an issue during our research. Since freezing and gait issues go hand-in-hand with cognitive and visual dysfunction, it is more common in advanced PD cases where the person probably isn’t or shouldn’t be driving anymore.
Would you allow a grandchild to ride in the car with a person with Parkinson’s?
In our research, we found that 25% of PD patients are normal. If we go back to the case scenarios, I would be fine to have my grandchild ride with that driver (even though I do not have a grandchild). With the second and third cases, I would have a hard time sending a grandchild with those drivers unless it was absolutely necessary or in an emergency. But it’s all context-dependent. Age, clinical subtypes of PD, and the duration of the person’s illness all play a part in determining someone’s ability to drive and function like normal.