Driving under low-contrast visibility conditions in Parkinson disease

Parkinson's Disease and Driving Fitness: A Systematic Review of the Existing Guidelines

BACKGROUND

Motor/nonmotor symptomatology and antiparkinsonian drugs deteriorate the driving ability of Parkinson's disease (PD) patients.

OBJECTIVES

Treating neurologists are frequently asked to evaluate driving fitness of their patients and provide evidence-based consultation. Although several guidelines have been published, the exact procedure along with the neurologist's role in this procedure remains obscure.

METHODS

We systematically reviewed the existing guidelines, regarding driving fitness evaluation of PD patients. We searched MEDLINE and Google Scholar and identified 109 articles. After specified inclusion criteria were applied, 15 articles were included (nine national guidelines, five recommendation papers, and one consensus statement).

RESULTS

The treating physician is proposed as the initial evaluator in 8 of 15 articles (neurologist in 2 articles) and may refer patients for a second-line evaluation. The evaluation should include motor, cognitive, and visual assessment (proposed in 15, 13, and 8 articles, respectively). Specific motor tests are proposed in eight articles (cutoff values in four), whereas specific neuropsychological and visual tests are proposed in seven articles each (cutoff values in four and three articles, respectively). Conditional licenses are proposed in 11 of 15 articles, to facilitate driving for PD patients. We summarized our findings on a graphic of the procedure for driving fitness evaluation of PD patients.

CONCLUSIONS

Neurological aspects of driving fitness evaluation of PD patients are recognized in most of the guidelines. Motor, neuropsychological, visual, and sleep assessment and medication review are key components. Clear-cut instructions regarding motor, neuropsychological, and visual tests and relative cutoff values are lacking. Conditional licenses and periodical reevaluation of driving fitness are important safety measures.

Does in-vehicle automation help individuals with Parkinson's disease? A preliminary analysis

Introduction

PD is a progressive neurodegenerative disorder that affects, according to the ICF, body systems (cognitive, visual, and motor), and functions (e.g., decreased executive functions, decreased visual acuity, impaired contrast sensitivity, decreased coordination)-all which impact driving performance, an instrumental activity of daily living in the domain of "Activity" and "Participation" according to the ICF. Although there is strong evidence of impaired driving performance in PD, few studies have explored the real-world benefits of in-vehicle automation technologies, such as in-vehicle information systems (IVIS) and advanced driver assistance systems (ADAS), for drivers with PD. These technologies hold potential to alleviate driving impairments, reduce errors, and improve overall performance, allowing individuals with PD to maintain their mobility and independence more safely and for longer periods. This preliminary study aimed to fill the gap in the literature by examining the impact of IVIS and ADAS on driving safety, as indicated by the number of driving errors made by people with PD in an on-road study.

Methods

Forty-five adults with diagnosed PD drove a 2019 Toyota Camry equipped with IVIS and ADAS features (Toyota Safety Sense 2.0) on a route containing highway and suburban roads. Participants drove half of the route with the IVIS and ADAS systems activated and the other half with the systems deactivated.

Results

The results suggest that systems that assume control of the driving task, such as adaptive cruise control, were most effective in reducing driving errors. Furthermore, individual differences in cognitive abilities, particularly memory, were significantly correlated with the total number of driving errors when the systems were deactivated, but no significant correlations were present when the systems were activated. Physical capability factors, such as rigidity and bradykinesia, were not significantly correlated with driving error.

Discussion

Taken together, these results show that in-vehicle driver automation systems can benefit drivers with PD and diminish the impact of individual differences in driver cognitive ability.

Real-World Driving Data Indexes Dopaminergic Treatment Effects in Parkinson's Disease

Background

Driving is a complex, everyday task that impacts patient agency, safety, mobility, social connections, and quality of life. Digital tools can provide comprehensive real-world (RW) data on driver behavior in patients with Parkinson's disease (PD), providing critical data on disease status and treatment efficacy in the patient's own environment.

Objective

This pilot study examined the use of driving data as a RW digital biomarker of PD symptom severity and dopaminergic therapy effectiveness.

Methods

Naturalistic driving data (3974 drives) were collected for 1 month from 30 idiopathic PD drivers treated with dopaminergic medications. Prescriptions data were used to calculate levodopa equivalent daily dose (LEDD). The association between LEDD and driver mobility (number of drives) was assessed across PD severity, measured by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS).

Results

PD drivers with worse motor symptoms based on self-report (Part II: P = 0.02) and clinical examination (Part III: P < 0.001) showed greater decrements in driver mobility. LEDD levels >400 mg/day were associated with higher driver mobility than those with worse PD symptoms (Part I: P = 0.02, Part II: P < 0.001, Part III: P < 0.001).

Conclusions

Results suggest that comprehensive RW driving data on PD patients may index disease status and treatment effectiveness to improve patient symptoms, safety, mobility, and independence. Higher dopaminergic treatment may enhance safe driver mobility in PD patients with worse symptom severity.

Driving Impairment in Movement Disorders

Background

Driving may be adversely affected by any movement disorder, but has been mostly studied in Parkinson's disease (PD). Few studies have addressed driving impairment in patients with Huntington's disease (HD); driving in other movement disorders such as dystonia, blepharospasm and Tourette syndrome (TS) has not been adequately evaluated.

Objectives

The aim of this review is to summarize the findings of driving impairment in movement disorders and evaluate the usefulness of clinical tools in guiding clinicians whether to refer patients for driving assessment.

Methods

A review of literature was performed on PubMed and articles on driving and movement disorders were identified using a Boolean phrase.

Results

We were able to identify 66 articles that fulfilled the target subject: impairment of driving in PD, cervical dystonia, blepharospasm, HD and TS. We also included articles discussing the role of driving rehabilitation in patients with movement disorders.

Conclusions

Driving is often impaired in patients with PD and other movement disorders not only due to motor symptoms but also because of cognitive and behavioral co-morbidities. Certain screening tools may be helpful in guiding the clinician in referring the patients for driving assessment.

Factors Influencing Driving following DBS Surgery in Parkinson's Disease: A Single UK Centre Experience and Review of the Literature

Parkinson's disease (PD) is a complex neurodegenerative disorder, leading to impairment of various neurological faculties, including motor, planning, cognitivity, and executive functions. Motor- and non-motor symptoms of the disease may intensify a patient's restrictions to performing usual tasks of daily living, including driving. Deep Brain Stimulation (DBS) associated with optimized clinical treatment has been shown to improve quality of life, motor, and non-motor symptoms in PD. In most countries, there are no specific guidelines concerning minimum safety requirements and the timing of return to driving following DBS, leaving to the medical staff of individual DBS centres the responsibility to draw recommendations individually regarding patients' ability to drive after surgery. The aim of this study was to evaluate factors that might influence the ability to drive following DBS in the management of PD. A total of 125 patients were included. Clinical, epidemiological, neuropsychological, and surgical factors were evaluated. The mean follow-up time was 129.9 months. DBS improved motor and non-motor symptoms of PD. However, in general, patients were 2.8-fold less likely to drive in the postoperative period than prior to surgery. Among the PD characteristics, patients with the akinetic subtype presented a higher risk to lose their driving licence postoperatively. Furthermore, the presence of an abnormal postoperative neuropsychological evaluation was also associated with driving restriction following surgery. Our data indicate that restriction to drive following surgery seems to be multifactorial rather than a direct consequence of DBS itself. Our study sheds light on the urgent need for a standardised multidisciplinary postoperative evaluation to assess patients' ability to drive following DBS.

Parkinson's disease affects gaze behaviour and performance of drivers

The aim of this study was to investigate the effects of PD and ageing on gaze behaviour and performance of drivers in a simulated task. Ten drivers with PD, ten neurologically healthy older drivers, and ten neurologically healthy younger adult drivers were asked to drive in a car simulator for three minutes, maintaining car speed between 100 and 120 km/h and avoiding collisions. Driver's eye movements were recorded. Drivers with PD had more collisions and spent less time driving within the speed zone than the younger-drivers. Drivers with PD performed an increased number of fixations towards task-irrelevant areas of the visual scene and higher visual entropy, indicating a more random gaze behaviour. Older drivers restricted their visual search to the lane area in order to detect threat-related stimuli. PD led to drops in performance of drivers in the car simulator. Practitioner summary: Parkinson's disease (PD) and ageing process caused a drop in driving performance. Drivers with PD made fewer fixations on task-relevant information and showed higher visual entropy than young adults. Older drivers restricted their visual search to the lane than other areas of interest.

RCT protocol for driving performance in people with Parkinson's using autonomous in-vehicle technologies

Introduction

Driving is an essential facilitator of independence, community participation, and quality of life. Drivers with Parkinson's Disease (PD) make more driving errors and fail on-road evaluations more than healthy controls. In-vehicle technologies may mitigate PD-related driving impairments and associated driving errors. Establishing a rigorous study protocol will increase the internal validity and the transparency of the scientific work.

Methods

We present a protocol to assess the efficacy of autonomous in-vehicle technologies (Level 1) on the driving performance of drivers with PD via a randomized crossover design with random allocation. Drivers with a PD diagnosis based on established clinical criteria (N = 105), referred by neurologists, are exposed to two driving conditions (technology activated or not) on a standardized road course as they drove a 2019 Toyota Camry. The researchers collected demographic, clinical, on-road data observational and kinematic, and video data to understand several primary outcome variables, i.e., number of speeding, lane maintenance, signaling, and total driving errors.

Discussion

The protocol may enhance participant adherence, decrease attrition, provide early and accurate identification of eligible participants, ensure data integrity, and improve the study flow. One limitation is that the protocol may change due to unforeseen circumstances and assumptions upon implementation. A strength is that the protocol ensures the study team executes the planned research in a systematic and consistent way.

Following, adapting, and refining the protocol will enhance the scientific investigation to quantify the nuances of driving among those with PD in the era of automated in-vehicle technologies.

Trial registration

ClinicalTrials.gov NCT04660500.

Comparison of the effects of alcohol and cannabis on visual function and driving performance. Does the visual impairment affect driving?

BACKGROUND

Alcohol and cannabis are the most widely consumed psychoactive substances worldwide. This study compared the effects of alcohol and cannabis on visual function and driving performance, as well as self-perceived effects. Also, the relationship between visual effects under the influence and driving performance was studied.

METHODS

Sixty-four young drivers, with a history of alcohol and/or cannabis use were included. Of these, 33 were allocated to the alcohol group and 31 to the cannabis group. All participants were evaluated in a baseline session. The alcohol group underwent two sessions: after drinking 300 ml and 450 ml of red wine (A1 and A2). The cannabis group attended one session after smoking cannabis (C). Visual function was evaluated at the contrast sensitivity, stereoacuity, and intraocular straylight level. Participants drove a driving simulator. A general score (overall visual score, OVS; overall driving performance score, ODPS) was obtained for both visual functioning and driving performance.

RESULTS

The evaluation of visual function demonstrated a significant impairment in OVS for all conditions studied (A1, p = 0.005; A2, p < 0.001; C, p < 0.001) with respect to the baseline session. General driving performance (ODPS) demonstrated a significant worsening for the A2 condition (p = 0.003). Finally, a significant relationship between driving performance and visual function was found (rho=0.163, p = 0.039 and χ² = 4.801, p = 0.028).

CONCLUSIONS

Cannabis and alcohol use negatively impact visual function. However, driving performance was only significantly affected by the higher alcohol dose. This impairment in visual function was significantly associated with worse driving performance.

Do Impulse Control Disorders Impair Car Driving Performance in Patients with Parkinson's Disease?

BACKGROUND

Based on data regarding the prevalence of Parkinson's disease (PD), the prevalence of impulsive control disorders (ICD) in PD, and the percentage of PD patients driving a car, it has to be assumed that at least 50,000 PD patients with ICD in Germany actively drive a car. However, these patients might be at risk for unsafe driving due to ICD-related dysfunctions such as failure to resist an impulse or temptation, to control an act or other altered neurobehavioral processes.

OBJECTIVE

This study determines the influence of ICD on driving ability in PD.

METHODS

We prospectively compared driving simulator performance of 23 PD patients with and 23 matched patients without ICD. ICD had to be socially compensated and presence was defined clinically for primary and questionnaire-based (QUIP-RS) for post-hoc analyses. Furthermore, between-group comparisons of driving-relevant neuropsychological tests were executed.

RESULTS

Except from a lower blinking frequency when changing lanes, overall driving safety of patients with ICD did not differ significantly from those without-regardless of the clinical or QUIP-RS-based ICD definition. ICD severity did not correlate with driving performance, but the latter correlated significantly with mean reaction times and certain neuropsychiatric tests (MoCA, TMT-A, TAP-M "flexibility" and DBQ "error").

CONCLUSION

Clinically compensated ICD does not seem to impair driving safety in PD patients. Rather, cognitive and attentional deficits appear to be clinical markers for driving uncertainty.

Impact of Visual Impairment on Vision-Related Quality of Life in Parkinson's Disease

BACKGROUND

Visual impairment is frequent and highly disabling in Parkinson's disease (PD); however, few studies have comprehensively evaluated its impact on vision-related quality of life.

OBJECTIVE

To evaluate the relationship between visual function tests and the visual impairment perceived by PD patients in daily living activities.

METHODS

We cross-sectionally evaluated 62 PD patients and 33 healthy controls (HC). Visual disability was measured with a comprehensive battery of primary visual function and visual cognition tests (visual outcomes), and vision-related quality of life was evaluated with the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25). The relationship between visual outcomes and NEI VFQ-25 sub-scores was analyzed with Pearson's correlations and stepwise linear regression.

RESULTS

In PD patients, and not in HC, most NEI VFQ-25 sub-scores were significantly correlated with Cube Analysis and Dot Counting from Visual Object and Space Perception (VOSP) battery (visual perception), Clock Drawing Test (visuoconstructive capacity) and Trail Making Test part-A (visual attention and processing speed) and to a lesser extent with high- and low-contrast visual acuity. Dot Counting (VOSP) was the test primarily associated with most NEI VFQ-25 sub-scores (5 out of 12). Roth-28 color test was the one that best explained the variance of Peripheral Vision (R2: 0.21) and Role Difficulties (R2: 0.36) sub-scores of NEI VFQ-25, while photopic contrast sensitivity explained 41% of Driving sub-score variance.

CONCLUSION

Vision-related quality of life in PD is mainly influenced by alterations in visual perception, visuoconstructive capacity and visual attention and processing speed. Future studies are warranted to confirm and further extend our findings.

Left Turns by Older Drivers With Vision Impairment: A Naturalistic Driving Study

BACKGROUND AND OBJECTIVES

Older drivers are overrepresented in collisions at intersections while making left turns across oncoming traffic. Using naturalistic driving methods, we evaluated the association between vision impairment and their left-turn characteristics.

RESEARCH DESIGN AND METHODS

In this prospective, observational study, vision impairment as defined by visual acuity, contrast sensitivity, visual processing speed, visual field sensitivity, and motion perception was assessed in drivers ≥70 years old. Data acquisition systems were installed in their personal vehicles recording video and vehicle kinematics. Driving during everyday life was recorded for 6 months. Data analysts evaluated a temporal data window surrounding randomly selected left turns at 4-way intersections. Left-turn traversals and turning behavior were evaluated in terms of age-adjusted associations with vision impairment.

RESULTS

The sample consisted of 151 older drivers. The number of turns studied was 473; 265 turns were rated as unsafe traversals, and 201 as problematic turning behavior. Drivers with slowed visual processing speed and visual field impairment were less likely to exhibit unsafe traversals (p < .05); those with worse contrast sensitivity, slowed visual processing speed, and visual field impairment were less likely to exhibit problematic turning behavior (p < .05).

DISCUSSION AND IMPLICATIONS

Using naturalistic driving, our study suggests older drivers with vision impairment exhibit better performance in making left turns than those without deficits, which contradicts older driver studies on left turns using driving simulators and on-road driving evaluations. Our findings suggest more cautious and self-regulatory behavior, which are consistent with older visually impaired drivers' commonly expressed concerns about their driving difficulties.

Using High-Frequency Information and RH to Estimate AQI Based on SVR

The Environmental Protection Administration of Taiwan’s Executive Yuan has set up many air quality monitoring stations to monitor air pollution in the environment. The current weather forecast also includes information used to predict air pollution. Since air quality indicators have a considerable impact on people, the development of a simple, fast, and low-cost method to measure the AQI value is a worthy topic of research. In this study, a method was proposed to estimate AQI. Visibility had a clear positive relationship with AQI. When images and AQI were compared, it was easy to see that visibility decreased with the AQI value increase. Distance is the main factor affecting visibility, so measuring visibility with images has also become a research topic. Images with high and low PM_2.5 concentrations were used to obtain regions of interest (RoI). The pixels in the RoI were calculated to obtain high-frequency information. The high-frequency information of RoI, RH, and true AQI was used for training via SVR, which was used to generate the model for AQI estimation. One year of experimental samples was collected for the experiment. Two indices were used to evaluate the performance of the proposed method. The results showed that the proposed method could be used to estimate AQI with acceptable performance in a simple, fast, and low-cost way.

Sparse group regularization for semi-continuous transportation data

Motor vehicle crashes are a global public health concern. Most analysis have used zero-inflated count models for examining crash counts. However, few methods are available to account for safety metrics that have semi-continuous observations. This article considers the problem of variable selection for the semi-continuous zero-inflated (SCZI) models. These models include two parts: a zero-inflated part and a nonzero continuous part. A special group regularization is designed to accommodate the unique structure of two-part SCZI models, and a type of Bayesian information criterion is proposed to select tuning parameters. We illustrate the variable selection process of the proposed model using lane position data from a driving simulator study. In the study, drivers stay in the intended lane for the majority of their drive (zero-inflated part). On occasion, some drivers do drift out of their intended driving lane (nonzero continuous part). Our findings show that individual differences can be captured with the proposed model, which has implications for driving safety and the design of in-vehicle alerting systems.

Driving in Parkinson's disease: a retrospective study of driving and mobility assessments

BACKGROUND

To guide decision-making about driving ability, some patients with Parkinson's disease (PD) undergo specialist driving assessment. However, decisions about driving safety in most patients need to be made without this definitive test. There is no consensus on what predicts unsafe driving in PD nor a validated prediction tool to guide clinician decision-making and the need to refer for further assessment.

OBJECTIVES

To describe the characteristics of patients with PD assessed at a Driving Mobility Centre and investigate factors that predict driving assessment outcome.

METHODS

Retrospective cohort study of patients with PD assessed between 2012 and 2016. Descriptive analyses and logistic models to determine factors predicting a negative outcome.

RESULTS

There were 86 assessments of patients with PD. The mean age was 70 years (±9.2), 86% were male, median disease duration 7 years (interquartile range 5-12.5 years) and 59% were referred by the Driver and Vehicle Licensing Agency. In total, 62% had a negative 'not drive' outcome. The Rookwood Driving Battery (RDB), depth of vision deficit, usual driving frequency, age, duration license held and response time were all predictors in univariable analysis. The RDB was the best predictor of assessment failure, conditional on other variables in a backward stepwise model (odds ratio 1.29; 95% confidence interval 1.05, 1.60; P = 0.015).

CONCLUSIONS

This is the first study to describe patients with PD undergoing driving assessments in the UK. In this population, RDB performance was the best predictor of outcome. Future prospective studies are required to better determine predictors of driving ability to guide development of prediction tools for implementation into clinical practice.

Approach to Cognitive Impairment in Parkinson's Disease

Cognitive dysfunction is common in Parkinson's disease (PD) and predicts poor clinical outcomes. It is associated primarily with pathologic involvement of basal forebrain cholinergic and prefrontal dopaminergic systems. Impairments in executive functions, attention, and visuospatial abilities are its hallmark features with eventual involvement of memory and other domains. Subtle symptoms in the premotor and early phases of PD progress to mild cognitive impairment (MCI) which may be present at the time of diagnosis. Eventually, a large majority of PD patients develop dementia with advancing age and longer disease duration, which is usually accompanied by immobility, hallucinations/psychosis, and dysautonomia. Dopaminergic medications and deep brain stimulation help motor dysfunction, but may have potential cognitive side effects. Central acetylcholinesterase inhibitors, and possibly memantine, provide modest and temporary symptomatic relief for dementia, although there is no evidence-based treatment for MCI. There is no proven disease-modifying treatment for cognitive impairment in PD. The symptomatic and disease-modifying role of physical exercise, cognitive training, and neuromodulation on cognitive impairment in PD is under investigation. Multidisciplinary approaches to cognitive impairment with effective treatment of comorbidities, proper rehabilitation, and maintenance of good support systems in addition to pharmaceutical treatment may improve the quality of life of the patients and caregivers.

Visual Impairment Is More Common in Parkinson's Disease and Is a Risk Factor for Poor Health Outcomes

BACKGROUND

Visual impairment is associated with hip fracture, depression, anxiety, and dementia in the general population, and many causes of visual impairment are preventable or treatable with early detection. However, the prevalence, outcomes, and healthcare utilization patterns associated with visual impairment have not been examined in Parkinson's disease (PD).

METHODS

We performed a cross-sectional analysis of all Medicare beneficiaries with complete data in 2014 and longitudinal analysis of beneficiaries with PD from 2010 to 2014. We used diagnosis and procedure codes to identify PD, visual impairment, eye exams, hip fracture, and neuropsychiatric disorders. We compared the prevalence of visual impairment using logistic regression and used Cox proportional hazards regression to examine visual impairment and incident hip fracture, depression, anxiety, dementia, and death. We also examined the frequency of eye exams in PD using repeated-measures logistic regression.

RESULTS

Among 26,209,997 Medicare beneficiaries in 2014, visual impairment was significantly more prevalent in PD (1.7%) than non-PD (0.71%) (adjusted odds ratio, 1.60; 95% confidence interval [CI], 1.56-1.65). In a longitudinal cohort of 542,224 Medicare beneficiaries with PD, less than 60% had a yearly eye exam. Visual impairment associated with increased hazard of depression (hazard ratio [HR], 1.23; 95% CI, 1.14-1.32), anxiety (HR, 1.34; 95% CI, 1.24-1.43), dementia (HR, 1.28; 95% CI, 1.21-1.36), and death (HR, 1.49; 95% CI, 1.44-1.55).

CONCLUSION

Visual impairment is more common in PD than the general population and is associated with negative PD-related outcomes. Understanding the mechanisms for these relationships is important for guiding future interventions to improve health outcomes in PD. © 2020 International Parkinson and Movement Disorder Society.

Brake time is correlated with lower extremity strength, dynamic balance and low-contrast sensitivity in unpredictable driving situations in elderly drivers compared with young drivers: A cross-sectional study

AIMS

To compare physical function, driving fitness and brake time of young and elderly drivers, and to identify the association of physical function and driving fitness with brake time in elderly drivers in predictable or unpredictable situations during driving.

METHODS

This study included 86 participants (50 men and 36 women), comprising 52 elderly drivers (age: 72.44 years, weight: 60.39 kg, height: 158.06 cm) and 34 young drivers (age: 26.53 years, weight: 63.74 kg, height: 153.65 cm), with a valid driver's license who drive at least once a week. Physical function was measured as upper and lower body flexibility and strength, dynamic balance and aerobic endurance. Driving fitness was measured as high- and low-contrast sensitivity, route planning, visualization of missing information, visual search with divided attention and visual information processing speed using the DrivingHealth® Inventory. Brake time and braking distance was evaluated as unpredictable and predictable driving situations.

RESULTS

Measurements of all categories, except lower extremity flexibility, endurance and high-contrast sensitivity, were significantly lower in elderly drivers than in young drivers. Brake time did not differ in predictable situations but was slower (P = 0.004) in elderly drivers in unpredictable situations. In elderly drivers, upper body strength (P = 0.036), dynamic balance (P < 0.001) and low-contrast sensitivity (P = 0.003) were associated with brake time in unpredictable driving situations.

CONCLUSIONS

In unpredictable situations, slower brake time in elderly drivers is associated with lower limb muscle strength, agility and low-contrast sensitivity. Therefore, for safe driving, these parameters should be considered as guidelines for maintaining the driving ability of elderly drivers and aging people. Geriatr Gerontol Int 2020; ••: ••-••.

Driving in Parkinson Disease

Driving is impaired in most patients with Parkinson disease because of motor, cognitive, and visual dysfunction. Driving impairments in Parkinson disease may increase the risk of crashes and result in early driving cessation with loss of independence. Drivers with Parkinson disease should undergo comprehensive evaluations to determine fitness to drive with periodic follow-up evaluations as needed. Research in rehabilitation of driving and automation to maintain independence of patients with Parkinson disease is in progress.

Contrast Acuity With Different Colors in Parkinson's Disease

Background

Abnormal color vision and contrast acuity may have significant impact on daily activities.

Objective

Evaluate color visual acuity, at high and low contrast, in Parkinson's disease (PD) and controls using an iPad application.

Methods

Color visual acuity was tested with the Variable Contrast Acuity Chart (King-Devick Test LLC, Oakbrook Terrace, IL) on an iPad 2 at 40 cms using five colors (red, green, blue, yellow, and black) at low (2.5%) and high (100%) contrast. A numerical score (0-95) was assigned based on the number of correctly identified letters.

Results

Thirty-six PD (mean ± standard deviation age 68 ± 10 years) and 36 controls (72 ± 11.2 years) were studied. PD disease duration was 6.4 ± 4.6 years; MDS-UPDRS part II was 11.7 ± 7.0, and part III was 24.5 ± 9.9. After adjusting for age and sex, PD patients had significantly (P < 0.05) lower scores at high (100%) as well as low (2.5%) contrast for all five colors tested (red, green, blue, yellow, and black), except yellow low contrast (2.5%; P = 0.10). The largest effect size (0.88) was with yellow high contrast, and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy using a cut-off score of 82 was 31%, 97%, 92%, 58%, and 64%, respectively. No correlation to disease duration was found.

Conclusions

This iPad application may be a simple-to-use biomarker for assessing color vision in PD. Further research is needed to determine disease specificity and whether there is a role in monitoring disease progression, treatment response, and identifying prodromal PD.

Preliminary study on visual recognition under low visibility conditions caused by artificial dynamic smog

AIM

To quantitatively evaluate the effect of a simulated smog environment on human visual function by psychophysical methods.

METHODS

The smog environment was simulated in a 40×40×60 cm³ glass chamber filled with a PM2.5 aerosol, and 14 subjects with normal visual function were examined by psychophysical methods with the foggy smog box placed in front of their eyes. The transmission of light through the smog box, an indication of the percentage concentration of smog, was determined with a luminance meter. Visual function under different smog concentrations was evaluated by the E-visual acuity, crowded E-visual acuity and contrast sensitivity.

RESULTS

E-visual acuity, crowded E-visual acuity and contrast sensitivity were all impaired with a decrease in the transmission rate (TR) according to power functions, with invariable exponents of -1.41, -1.62 and -0.7, respectively, and R² values of 0.99 for E and crowded E-visual acuity, 0.96 for contrast sensitivity. Crowded E-visual acuity decreased faster than E-visual acuity. There was a good correlation between the TR, extinction coefficient and visibility under heavy-smog conditions.

CONCLUSION

Increases in smog concentration have a strong effect on visual function.

Altered driving performance of symptomatic Huntington's disease gene carriers in simulated road conditions

OBJECTIVE

In clinical practice, patients with Huntington's disease (HD) often decide to solely drive in their own familiar neighborhoods and not on a motorway or in an unknown area. The aim of the study was to identify differences in driving performance between HD gene carriers and healthy individuals in simulated urban and motorway environments.

METHODS

This cross-sectional study included 87 participants (28 premanifest HD, 30 manifest HD, 29 controls). All participants were active drivers and were assessed using a driving simulator, a driving history questionnaire, and the Unified Huntington's Disease Rating Scale. The driving simulator session included urban and motorway scenarios. Analysis of variance and Kruskal-Wallis tests were used to compare urban and motorway driving across all 3 groups.

RESULTS

Manifest HD drove slower compared to controls and premanifest HD when speed limits increased (80 and 100 km/h) and they had a less steady speed compared to premanifest HD on the motorway and in a 30 km/h zone. Manifest HD also had a larger standard deviation of the lateral position (i.e., more weaving of the car/less vehicle control) compared to controls and premanifest HD on the motorway.

CONCLUSIONS

Manifest HD drive more cautious in a driving simulator when speed limits increase compared to premanifest HD and controls and they have less vehicle control on the motorway. The driving simulator parameters are able to discriminate between manifest HD and healthy individuals, so a driving simulator seems a feasible tool to use when investigating changes in driving in manifest HD.

Evidence of attentional impairments using virtual driving simulation in multiple sclerosis

BACKGROUND

Detection of attentional disorders in complex situation related to daily life activities in multiple sclerosis patients needs better adapted tools than traditional cognitive assessment.

OBJECTIVE

To investigate the usefulness of virtual reality assessment of attention in multiple sclerosis, especially to evaluate alertness and divided attention using driving simulation.

METHODS

In this preliminary study, 11 relapsing-remitting patients (median EDSS: 2; mean disease duration of 10.3 years) and 11 healthy matched controls performed a driving simulation under three conditions (monotonous driving, divided attention driving and urban driving) where Standard Deviation of Lateral position (SDLP) was the main evaluated criteria. In comparison, traditional cognitive assessment of attentional functions was administered (SDMT, alertness and divided attention of TAP battery). Statistical non-parametric Mann-Whitney U tests were used to compare performances between groups in the two types of assessments. Exploratory correlational analyses were further conducted.

RESULTS

No significant difference was observed between groups for traditional attentional assessment except for information processing speed (SDMT; p < 0.01). Considering virtual reality, patients were less efficient than controls on the primary parameter of safe driving (SDLP; p < 0.05). They also committed more errors and omissions (p < 0.01) and speed fluctuations (p < 0.01) during the divided-attention driving condition. Urban driving did not reveal difference between groups. Lack of significant correlations between traditional and virtual reality attentional assessment suggested that they do not evaluate the same cognitive processes.

CONCLUSION

Patients experienced difficulties in maintaining the trajectory and the speed of the simulated vehicle which may be indicative of attentional difficulties, especially alertness and divided attention. These impairments were not revealed by the traditional cognitive assessment. Results of this preliminary study shed new light about the usefulness of virtual reality techniques and their future interest as a part of cognitive rehabilitation programs. They also highlights the need to develop driving preventive measures in MS.

Driving impairment and crash risk in Parkinson disease: A systematic review and meta-analysis

OBJECTIVES

To provide the best possible evidence base for guiding driving decisions in Parkinson disease (PD), we performed a meta-analysis comparing patients with PD to healthy controls (HCs) on naturalistic, on-the-road, and simulator driving outcomes.

METHODS

Seven major databases were systematically searched (to January 2018) for studies comparing patients with PD to HCs on overall driving performance, with data analyzed using random-effects meta-analysis.

RESULTS

Fifty studies comprising 5,410 participants (PD = 1,955, HC = 3,455) met eligibility criteria. Analysis found the odds of on-the-road test failure were 6.16 (95% confidence interval [CI] 3.79-10.03) times higher and the odds of simulator crashes 2.63 (95% CI 1.64-4.22) times higher for people with PD, with poorer overall driving ratings also observed (standardized mean differences from 0.50 to 0.67). However, self-reported real-life crash involvement did not differ between people with PD and HCs (odds ratio = 0.84, 95% CI 0.57-1.23, p = 0.38). Findings remained unchanged after accounting for any differences in age, sex, and driving exposure, and no moderating influence of disease severity was found.

CONCLUSIONS

Our findings provide persuasive evidence for substantive driving impairment in PD, but offer little support for mandated PD-specific relicensure based on self-reported crash data alone, and highlight the need for objective measures of crash involvement.

Contrast sensitivity and motion discrimination in cannabis users

RATIONALE

Cannabis use impairs visual attention; however, it is unclear whether cannabis use also impairs low level visual processing or whether low level visual deficits can be related to lower dopaminergic functioning found in cannabis users.

OBJECTIVES

To investigate whether spatiotemporal contrast sensitivity and motion discrimination under normal and low luminance conditions differ in cannabis users and non-users.

METHODS

Control (n = 20) and cannabis (n = 21) participants completed a visual acuity test, a saliva test and self-report measures. Spatial and temporal contrast thresholds, motion coherence thresholds for translational and radial motion and the spontaneous eye blink rate were then collected.

RESULTS

Cannabis users showed decreased spatial contrast sensitivity under low luminance conditions and increased motion coherence thresholds under all luminance levels tested compared to non-users. No differences in temporal contrast sensitivity were found between the groups. Frequency of cannabis use correlated significantly and negatively with contrast sensitivity, both spatial and temporal, in the cannabis group and higher motion coherence thresholds for radial motion were also associated with more frequent cannabis use in this group. The eye blink rate was significantly lower in cannabis users compared to non-users.

CONCLUSIONS

The present study shows that cannabis use is associated with deficits in low level visual processing. Such deficits are suggested to relate to lower dopamine, in a similar manner as in clinical populations. The implications for driving safety under reduced visibility (e.g. night) in abstaining cannabis users are discussed.

Driving with Parkinson's disease: Cut points for clinical predictors of on-road outcomes: La conduite automobile et la maladie de Parkinson : Points de découpage pour les prédicteurs clinique des résultats des épreuves sur route

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disorder that impacts a person's fitness to drive. Practitioners require a sensitive and predictive battery of clinical tests to identify at-risk drivers.

PURPOSE

This study aimed to identify clinical predictors and their optimal cut points, sensitivity, specificity, and predictive values of on-road outcomes in drivers with PD.

METHOD

Participants ( N = 101) underwent a comprehensive driving evaluation. We identified predictors of pass/fail outcomes through logistic regression and computed optimal cut points through receiver operating characteristic curves and corresponding Youden indexes.

FINDINGS

The Trail Making Test Part B (Trails B; sensitivity = .89, specificity = .74; positive predictive value [PPV] = .71; negative predictive value [NPV] = .91) and contrast sensitivity (sensitivity = .82, specificity = .63; PPV = .61; NPV = .84) emerged as significant predictors. The optimal cut point for the Trails B was 108 s (area under the curve = .86).

IMPLICATIONS

Occupational therapists can benefit from implementing Trails B and contrast sensitivity screening as part of in-office screening of potentially at-risk drivers with PD.

Relationship between neuropsychological tests and driver's license renewal tests in Parkinson's disease

OBJECTIVE

To determine whether the standard Spanish driving test (ASDE test) was able to identify patients with Parkinson's disease (PD) at risk of unsafe driving and to examine the relationship between the ASDE test and the Useful Field of View (UFOV) as well as with a battery of neuropsychological tests in drivers with PD.

METHODS

Thirty-seven patients with PD and 33 controls matched by age and education level were included in an observational study. All participants were active drivers and patients with PD underwent study procedures after taking the medication in the "on" period. Subjects with a Mini-Mental State Examination (MMSE) score ≤ 24 were excluded. Neuropsychological tests (Repeatable Battery for Neuropsychological Status [RBANS], Trail Making Test [TMT-A and -B], and Block Design test), driving performance tests (ASDE Driver Test and UFOV), and daytime sleepiness (Epworth Sleepiness Scale) were assessed.

RESULTS

The PD group performed significantly worse than healthy controls in the ASDE Motor Coordination tests. No significant differences were observed in anticipation speed, multiple reaction time, concentrated attention, and resistance to monotony. All participants successfully completed the UFOV tests. Statistically significant differences between patients with PD and controls were found in processing speed (UFOV1; P =.03) and more patients with PD were found in the categories of higher driving risk levels (P =.03). In addition, patients with PD showed worse scores than healthy controls in visuospatial capacities (Line Orientation), psychomotor speed (Coding and TMT-A), memory (List Recognition, Story Recall), and executive function (TMT-B). The driving tests (ASDE and UFOV) showed a low sensitivity and a high specificity but a higher percentage of patients in the PD group failed in multiple reaction time, concentrated attention, and resistance to monotony. In addition, 18.9% of patients with PD showed a cutoff of 4 for UFOV risk. In the discriminant analysis, Line Orientation (visuospatial/constructive domain) and Figure Recall (delayed memory) were found to be statistically significant with a rate of correct classification of unsafe drivers with PD of 78.2%. In addition, normal results on the Line Orientation item were associated with a 1.5 times higher probability of non-risky driving in the multivariate analysis.

CONCLUSIONS

At early stages of the disease, about 19% of patients with PD showed difficulties that may affect their driving capabilities. Line Orientation and Figure Recall are useful to alert clinicians to the risk of unsafe driving. For this reason, patients with PD should be evaluated for driving abilities more regularly to determine the extent of deficits that may influence driving performance.

Visual attention to motion stimuli and its neural correlates in cannabis users

Attention to motion stimuli and correct motion perception are vital for road safety. Although cannabis use has been associated with increased road crash risks, there is limited research on attentional processing of moving stimuli in cannabis users. This study investigated the neural correlates of the three-stimulus oddball task in cannabis users (n = 18) and non-users (n = 23) in response to moving stimuli. Stimulus contrast was under 16% against a low luminance background (M luminance < 16 cd/m² ). The two groups did not differ in accuracy or in N2 peak amplitude; however, N2 latency was longer for target and standard stimuli in the cannabis group than in the control group. The cannabis group also showed a significantly reduced P3b amplitude in response to target stimuli. The AUDIT score was added as a random factor to the anova to rule out the effects of uneven alcohol consumption in the two groups. A significant group effect was found for N2 latency in response to target and standard stimuli and a significant interaction between the group, and the AUDIT score was found for the P3b peak amplitude for the distractor and standard stimuli, but not for the target stimuli. The results of this study suggest that cannabis use relates to reduced neural activity underlying attention to motion stimuli. Implications for regular early-onset cannabis use road safety are discussed.

Self-perception and determinants of color vision in Parkinson's disease

Visual dysfunction is common in patients with Parkinson's disease (PD). The objective of this study was to investigate the perceived impact of visual dysfunction and especially color vision loss on PD patients, and to identify retinal and disease factors associated with color vision. Thirty PD patients and thirty-four healthy controls were included. Participants performed the Farnsworth-Munsell Hue-100 test (FMT). Patients answered the National Eye Institute Visual Function Questionnaire (NEI-VFQ), Unified Parkinson's Disease Rating Scale (UPDRS) assessment, and underwent optical coherence tomography with measurement of retinal nerve fiber layer, ganglion cell layer + inner plexiform layer (GCIPL), and outer nuclear and photoreceptor layer. Dopaminergic treatment was assessed as levodopa equivalent dose (LED). Vision domains significantly worse in PD patients compared to normative data were General Vision, Near Activities, Distance Activities, Vision-Specific Dependency, Driving, and Peripheral Vision. Worse NEI-VFQ total scores were associated with worse UPDRS, higher LED, and higher age, but not with FMT, visual acuity, or OCT measures. Only two patients (7%) reported problems with color vision. In contrast, patients performed significantly worse in the FMT than healthy controls and 17 (56.7%) patients were outside the 95th percentile of normative data. In multiple regression analyses, lower LED and higher age were associated with worse color vision in the FMT. PD patients are not aware of color vision deficits. Given the impact of color vision loss on everyday tasks in other conditions, future research should investigate the impact of vision deficits on disease burden in PD.

Longitudinal decline of driving safety in Parkinson disease

OBJECTIVE

To longitudinally assess and predict on-road driving safety in Parkinson disease (PD).

METHODS

Drivers with PD (n = 67) and healthy controls (n = 110) drove a standardized route in an instrumented vehicle and were invited to return 2 years later. A professional driving expert reviewed drive data and videos to score safety errors.

RESULTS

At baseline, drivers with PD performed worse on visual, cognitive, and motor tests, and committed more road safety errors compared to controls (median PD 38.0 vs controls 30.5; p < 0.001). A smaller proportion of drivers with PD returned for repeat testing (42.8% vs 62.7%; p < 0.01). At baseline, returnees with PD made fewer errors than nonreturnees with PD (median 34.5 vs 40.0; p < 0.05) and performed similar to control returnees (median 33). Baseline global cognitive performance of returnees with PD was better than that of nonreturnees with PD, but worse than for control returnees (p < 0.05). After 2 years, returnees with PD showed greater cognitive decline and larger increase in error counts than control returnees (median increase PD 13.5 vs controls 3.0; p < 0.001). Driving error count increase in the returnees with PD was predicted by greater error count and worse visual acuity at baseline, and by greater interval worsening of global cognition, Unified Parkinson's Disease Rating Scale activities of daily living score, executive functions, visual processing speed, and attention.

CONCLUSIONS

Despite drop out of the more impaired drivers within the PD cohort, returning drivers with PD, who drove like controls without PD at baseline, showed many more driving safety errors than controls after 2 years. Driving decline in PD was predicted by baseline driving performance and deterioration of cognitive, visual, and functional abnormalities on follow-up.

Driving with a neurodegenerative disorder: an overview of the current literature

Driving is important for employment, social activities, and for the feeling of independence. The decision to cease driving affects the quality of life and has been associated with reduced mobility, social isolation, and sadness. Patients with neurodegenerative disorders can experience difficulties while driving due to their cognitive, motor, and behavioral impairments. The aim of this review is to summarize the available literature on changes in driving competence and behavior in patients with neurodegenerative disorders, with a particular focus on Huntington's (HD), Parkinson's (PD), and Alzheimer's disease (AD). A systematic literature search was conducted in the PubMed/Medline database. Studies using on-road or simulated driving assessments were examined in this review. In addition, studies investigating the association between cognitive functioning and driving were included. The review identified 70 studies. Only a few publications were available on HD (n = 7) compared to PD (n = 32) and AD (n = 31). This review revealed that driving is impaired in patients with neurodegenerative disorders on all levels of driving competence. The errors most commonly committed were on the tactical level including lane maintenance and lane changing. Deficits in executive functioning, attention, and visuospatial abilities can partially predict driving competence, and the performance on neuropsychological tests might be useful when discussing potential driving cessation. Currently, there is no gold standard to assess driving ability using clinical measures such as neuropsychological assessments, so more studies are necessary to detect valid screening tools and develop useful and reliable evidence-based guidelines.

Association of Parkinson's disease with hospitalization for traumatic brain injury

PURPOSE

The goal of our study was to determine if patients with Parkinson's disease (PD) are more susceptible to hospitalization for traumatic brain injury (TBI).

METHODS

The US Nationwide Inpatient Sample database was queried (2004-2011) to identify cohorts of patients with PD (N = 1 047 656) and without PD (N = 115 95 173). The age range of the study population was 60-89 years. The incidence of TBI among patients with PD was compared to the incidence of TBI in patients without PD. A multivariate logistic regression model, adjusted for all covariates that significantly differed in the bivariate analyses, was used to determine if PD was an independent predictor of TBI hospitalization.

RESULTS

The incidence of TBI hospitalization was significantly higher (relative risk: 1.76, 95% CI: 1.73-1.80) in the PD cohort. The PD cohort with TBI had fewer comorbidities and risk factors for falls/TBI compared to the non-PD cohort with TBI. The multivariable analysis, adjusting for other TBI risk factors, revealed that PD status increased the likelihood of TBI hospitalization (odds ratio: 2.99, 95% CI: 2.93-3.05).

CONCLUSION

Our study shows that patients with PD are more susceptible to hospitalization for TBI. A greater proportion of fall-related TBI occurs in patients with PD compared to patients without PD. Further research is needed to prevent falls in PD patients to avoid TBI.

Impaired contrast sensitivity is associated with more severe cognitive impairment in Parkinson disease

OBJECTIVES

Dopaminergic degeneration affects both nigrostriatal projection neurons and retinal amacrine cells in Parkinson disease (PD). Parkinsonian retinopathy is associated with impaired color discrimination and contrast sensitivity. Some prior studies described associations between color discrimination deficits and cognitive deficits in PD, suggesting that contrast discrimination deficits are due, at least in part, to cognitive deficits in PD. We investigated the relationship between cognitive deficits and impaired contrast sensitivity in PD.

METHODS

PD subjects, n = 43; 15F/28M; mean age 66.5 ± 8.2, Hoehn and Yahr stage 2.6 ± 0.6, and duration of disease of 6.2 ± 5.0 years underwent neuropsychological and Rabin contrast sensitivity testing.

RESULTS

Mean Rabin contrast sensitivity score was 1.34 ± 0.40. Bivariate analyses showed significant correlation between Rabin contrast sensitivity scores and global cognitive z-scores (R = 0.54, P = 0.0002). Cognitive domain Z-score post hoc analysis demonstrated most robust correlation between Rabin scores and executive functions (R = 0.49, P = 0.0009), followed by verbal learning (R = 0.44, P = 0.0028), visuospatial (R = 0.39, P = 0.001) and attention z-scores (R = 0.32, P = 0.036).

CONCLUSIONS

Impaired contrast sensitivity in PD is robustly associated with cognitive deficits, particularly executive function deficits. These results suggest that contrast sensitivity may be a useful biomarker for cognitive changes in PD and may have implications for driving safety evaluations in PD.

Physicians' role in the determination of fitness to drive in patients with Parkinson's disease: systematic review of the assessment tools and a call for national guidelines

BACKGROUND

Physicians are usually at the forefront when the issue of driving ability is raised by Parkinson's disease (PD) patients or their family members, even though few have been formally trained in this area.

OBJECTIVES AND METHODS

To identify relevant literature on driving assessment tools in patients with PD by performing a systematic review on this subject in order to provide background information for physicians on what types of driving assessment are available, and to delineate the role of physicians in providing fitness to drive recommendations.

RESULTS

Of 1,490 abstracts screened, 55 articles fulfilled the selection criteria that investigated assessment of driving ability in PD patients with questionnaires, off-road testing battery, driving simulators, and driving skill tests (on-road tests and naturalistic driving test). Despite different methodology across studies, PD patients were observed to commit more driving errors than controls. Poor driving performance correlated with motor, visual, and cognitive severity. Excessive daytime somnolence was common in PD drivers and the presence of falling asleep while driving was identified to be a significant predictor of car accidents.

CONCLUSION

Although the evidence indicated more driving errors among PD drivers as identified by various assessment tools, the extent on how physicians should be involved in the evaluation process and make related recommendations remain unclear. Driving safety is an important public health issue in PD that needs better-defined specific legal and medical guidelines. National guidelines that establish risk assessment protocols involving multidisciplinary assessments are needed to assist physicians in making appropriate referrals for additional evaluations and recommendations when patients are deemed to be unsafe drivers.

Exploring the association between working memory and driving performance in Parkinson's disease

OBJECTIVE

The aim of this study was to explore whether varying levels of operational and tactical driving task demand differentially affect drivers with Parkinson's disease (PD) and control drivers in their sign recall.

METHODS

Study participants aged between 50 and 70 years included a group of drivers with PD (n = 10) and a group of age- and sex-matched control drivers (n = 10). Their performance in a sign recall task was measured using a driving simulator.

RESULTS

Drivers in the control group performed better than drivers with PD in a sign recall task, but this trend was not statistically significant (P =.43). In addition, regardless of group membership, subjects' performance differed according to varying levels of task demand. Performance in the sign recall task was more likely to drop with increasing task demand (P =.03). This difference was significant when the variation in task demand was associated with a cognitive task; that is, when drivers were required to apply the instructions from working memory.

CONCLUSIONS

Although the conclusions drawn from this study are tentative, the evidence presented here is encouraging with regard to the use of a driving simulator to examine isolated cognitive functions underlying driving performance in PD. With an understanding of its limitations, such driving simulation in combination with functional assessment batteries measuring physical, visual, and cognitive abilities could comprise one component of a multitiered system to evaluate medical fitness to drive.

Cognitive impairment and dementia in Parkinson's disease: practical issues and management

Cognitive impairment and dementia pose particular challenges in the management of patients with Parkinson's disease (PD). Decision-making capacity can render patients vulnerable in a way that requires careful ethical considerations by clinicians with respect to medical decision making, research participation, and public safety. Clinicians should discuss how future decisions will be made as early in the disease course as possible. Because of cognitive, visual, and motor impairments, PD may be associated with unsafe driving, leading to early driving cessation in many. DBS of the STN and, to a lesser degree, globus pallidus interna (GPi) has consistently been associated with decreased verbal fluency, but significant global cognitive decline is usually not observed in patients who undergo rigorous selection. There are some observations suggesting lesser cognitive decline in GPi DBS than STN DBS, but further research is required. Management of PD dementia (PDD) patients involves both pharmacological and nonpharmacological measures. Patients with PDD should be offered treatment with a cholinesterase inhibitor taking into account expected benefits and potential risks. Treatment with neuroleptics may be necessary to treat psychosis; classical neuroleptics, as well as risperidone and olanzapine, should be avoided. Quetiapine might be considered first-line treatment because it does not need special monitoring, although the strongest evidence for efficacy exists for clozapine. Evidence from randomized, controlled studies in the PDD population is lacking; selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors may be used to treat depressive features. Clonazepam or melatonin may be useful in the treatment of rapid eye movement behavior disorder.

Driving errors in Parkinson's disease: moving closer to predicting on-road outcomes

Age-related medical conditions such as Parkinson's disease (PD) compromise driver fitness. Results from studies are unclear on the specific driving errors that underlie passing or failing an on-road assessment. In this study, we determined the between-group differences and quantified the on-road driving errors that predicted pass or fail on-road outcomes in 101 drivers with PD (mean age = 69.38 ± 7.43) and 138 healthy control (HC) drivers (mean age = 71.76 ± 5.08). Participants with PD had minor differences in demographics and driving habits and history but made more and different driving errors than HC participants. Drivers with PD failed the on-road test to a greater extent than HC drivers (41% vs. 9%), χ²(1) = 35.54, HC N = 138, PD N = 99, p < .001. The driving errors predicting on-road pass or fail outcomes (95% confidence interval, Nagelkerke R² =.771) were made in visual scanning, signaling, vehicle positioning, speeding (mainly underspeeding, t(61) = 7.004, p < .001, and total errors. Although it is difficult to predict on-road outcomes, this study provides a foundation for doing so.

Are patients with Parkinson's disease blind to blindsight?

In Parkinson's disease, visual dysfunction is prominent. Visual hallucinations can be a major hallmark of late stage disease, but numerous visual deficits also occur in early stage Parkinson's disease. Specific retinopathy, deficits in the primary visual pathway and the secondary ventral and dorsal pathways, as well as dysfunction of the attention pathways have all been posited as causes of hallucinations in Parkinson's disease. We present data from patients with Parkinson's disease that contrast with a known neuro-ophthalmological syndrome, termed 'blindsight'. In this syndrome, there is an absence of conscious object identification, but preserved 'guess' of the location of a stimulus, preserved reflexive saccades and motion perception and preserved autonomical and expressive reactions to negative emotional facial expressions. We propose that patients with Parkinson's disease have the converse of blindsight, being 'blind to blindsight'. As such they preserve conscious vision, but show erroneous 'guess' localization of visual stimuli, poor saccades and motion perception, and poor emotional face perception with blunted autonomic reaction. Although a large data set on these deficits in Parkinson's disease has been accumulated, consolidation into one specific syndrome has not been proposed. Focusing on neuropathological and physiological data from two phylogenetically old and subconscious pathways, the retino-colliculo-thalamo-amygdala and the retino-geniculo-extrastriate pathways, we propose that aberrant function of these systems, including pathologically inhibited superior colliculus activity, deficient corollary discharges to the frontal eye fields, dysfunctional pulvinar, claustrum and amygdaloid subnuclei of the amygdala, the latter progressively burdened with Lewy bodies, underlie this syndrome. These network impairments are further corroborated by the concept of the 'silent amygdala'. Functionally being 'blind to blindsight' may facilitate the highly distinctive 'presence' or 'passage' hallucinations of Parkinson's disease and can help to explain handicaps in driving capacities and dysfunctional 'theory of mind'. We propose this synthesis to prompt refined neuropathological and neuroimaging studies on the pivotal nuclei in these pathways in order to better understand the networks underpinning this newly conceptualized syndrome in Parkinson's disease.

Drivers with Parkinson's disease: are the symptoms of PD associated with restricted driving practices?

This study examined whether symptoms (motor, cognitive, vision, sleepiness, depression) of Parkinson's disease (PD) were associated with restricted driving practices. To quantify driving practices, electronic devices were installed in the vehicles of 27 drivers with PD (78 % men; M = 71.6, SD = 6.6; Unified Parkinson's Disease Rating Scale (UPDRS) motor score M = 30.1, SD = 8.6; disease duration M = 3.9, SD = 2.8 years) and 20 controls (80 % men; M = 70.6, SD = 7.9) for 2 weeks. Participants completed measures of sleepiness, depression, quality of life, and assessments of motor, cognitive and visual functions. The PD group had significantly slower brake response times (p < 0.05), poorer cognitive and quality of life scores (p < 0.01) and greater depression (p < 0.05) compared to controls. Slower reaction time was significantly related to reduced driving; specifically, fewer trips (r = -0.46; p < 0.05), distance (r = -0.54, p < 0.01) and duration at night (r = -0.58, p < 0.01). Better cognitive scores were associated with driving less often in difficult situations such as bad weather and rush hour (p < 0.05), as well as reduced speed on city streets, but only for the control group. While most drivers with PD rated their overall health as good or excellent, the five PD drivers who rated their health more poorly had significantly worse clinical symptoms (UPDRS motor scores, contrast sensitivity, depression, brake response time) and more restricted driving patterns. These findings show that drivers with PD who perceive their health poorly have greater symptomatology and were more likely to restrict their driving, possibly due to noticeable declines in multiple driving-related abilities.

Driving with bioptic telescopes: organizing a research agenda

Being a licensed driver in the United States and many other countries facilitates health and well-being. Based on the vision standards in most states, individuals with worse than 20/40 visual acuity who desire licensure are denied through the usual licensure application process. However, >40 states have bioptic telescope licensing programs where applicants can gain licensure contingent on meeting specific requirements. Despite the existence of the bioptic telescope and these licensing programs since the 1970s, there has been little rigorous scientific study of this topic. Here, I offer an organizing perspective for a research agenda on driving with bioptic telescopes, with the long-term practical goal being to provide an evidence basis for licensure policies and training programs.

Parkinson disease and driving: an evidence-based review

The growing literature on driving in Parkinson disease (PD) has shown that driving is impaired in PD compared to healthy comparison drivers. PD is a complex neurodegenerative disorder leading to motor, cognitive, and visual impairments, all of which can affect fitness to drive. In this review, we examined studies of driving performance (on-road tests and simulators) in PD for outcome measures and their predictors. We searched through various databases and found 25 (of 99) primary studies, all published in English. Using the American Academy of Neurology criteria, a study class of evidence was assigned (I-IV, I indicating the highest level of evidence) and recommendations were made (Level A: predictive or not; B: probably predictive or not; C: possibly predictive or not; U: no recommendations). From available Class II and III studies, we identified various cognitive, visual, and motor measures that met different levels of evidence (usually Level B or C) with respect to predicting on-road and simulated driving performance. Class I studies reporting Level A recommendations for definitive predictors of driving performance in drivers with PD are needed by policy makers and clinicians to develop evidence-based guidelines.

Examination of naturalistic driving practices in drivers with Parkinson's disease compared to age and gender-matched controls

A few studies suggest that drivers with Parkinson's disease (PD) may self-regulate or modify their driving behavior more than drivers without neurological disorders; however findings are limited to self-report. The purpose of this study was to objectively examine whether drivers with PD show more restrictive driving practices (exposure and patterns). Electronic devices were installed in the vehicles of 27 drivers with PD (71.6±6.6; 78% men) and 20 matched controls (70.6±7.9; 80% men) for two weeks and driving data were matched with aerial maps, weather and daylight archives and trip logs to examine driving context. Compared to controls, the PD group drove significantly less overall (number of trips, kilometres, duration), and proportionately less at night and on days with bad weather suggesting more restricted driving practices, congruent with lower ratings of driving comfort and abilities. However, they may not necessarily drive more cautiously or safely as they drove significantly faster (and over the speed limit) on highways and freeways and 19% reported driving problems over the two weeks. These preliminary findings need to be replicated and longitudinal studies using objective indicators are needed to examine changes in driving practices, as well as crash outcomes, as disease severity progresses.

Driving performance and behaviors: a comparison of gender differences in Parkinson's disease

OBJECTIVE

The primary objective of this study was to determine gender differences by comparing self-reported driving behaviors, clinical tests, and on-road driving performance in a cohort of men and women drivers with Parkinson's disease (PD).

METHODS

In this prospective observational study, we analyzed data of a convenience sample of 63 men (mean age = 70.9 ± 6.6 years) and 21 women (mean age 67.1 ± 7.3 years) with diagnosed PD. All participants underwent a comprehensive driving evaluation by a certified driving rehabilitation specialist.

RESULTS

On average, both men and women were active drivers (driving ∼4.6 times/week). A substantial proportion of both groups avoided driving at night (40% of men versus 46% of women), during rush hour, and in heavy traffic (36% of men versus 57% of women), although the differences were not significant. Both groups reported some avoidance behaviors: making left-hand turns (9.7% men versus 9.5% women), driving in the rain (12.9% men versus 19.0% women), or on the interstate/highway (14.3% men versus 7.7% women). With respect to driving performance, both groups were equally likely to fail the on-road test (42.6% men versus 42.9% women). Although men committed slightly more total driving errors compared to women, the differences were not statistically significant. Specific driving errors also did not differ by gender. Controlling for gender and disease severity, age was an independent predictor of total driving errors in men but not in women. Additionally, a cut-point of ≥2.5 on the modified Hoehn and Yahr was predictive of pass-fail outcomes in men when controlling for age.

CONCLUSIONS

Our study shows preliminary evidence that few gender differences exist with respect to driving errors and overall driving performance. Future studies should better balance gender distribution by age in PD driving studies to determine whether there are indeed differences in driving performance between men and women.