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1.  Anxiety of Alzheimer’s disease patients before and after a standardized on-road driving test 
A large number of licensed elderly drivers are demented or are likely to become demented. On-road driving tests, a method often used to assess driver competency, are likely anxiety-provoking for elderly individuals. This article examines the relationship between anxiety and driving performance in a mildly demented and elderly control (EC) sample.
Anxiety ratings of fear and tension, as assessed by visual analog scales, of 84 patients clinically diagnosed with mild Alzheimer’s disease (AD) (68 safe/marginal and 16 unsafe drivers) were compared with those of 44 age- and education-equated safe/marginal EC participants, both before and after a standardized on-road driving test.
Analyses revealed significant positive correlations between AD patients’ pre–road test and post–road test tension and post–road test fear ratings and total road test score. Subsequent analyses of variance showed no significant pre–road test differences in fear ratings between the three groups but significantly higher levels of tension among the unsafe AD participants. After adjusting for baseline group differences, unsafe AD drivers experienced stable or higher anxiety levels after road test, whereas both the EC and safe/marginal AD drivers endorsed a significant reduction in anxiety.
Unlike their safe EC and safe AD driver counterparts, unsafe AD patients reported continued elevated levels of fear and tension after the road test. Given these findings, we suggest that the most appropriate time for driving instructors to counsel patients regarding their driving skills might be directly after the road test.
PMCID: PMC3598633  PMID: 19595915
Alzheimer’s disease; Driving; Road test; Anxiety; Visual analog mood scales
2.  Driving with Binocular Visual Field Loss? A Study on a Supervised On-Road Parcours with Simultaneous Eye and Head Tracking 
PLoS ONE  2014;9(2):e87470.
Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs) that may critically interfere with quality of life and driving licensure. The aims of this study were (i) to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii) to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed) of ten patients with homonymous visual field defects (HP), including four patients with right (HR) and six patients with left homonymous visual field defects (HL), ten glaucoma patients (GP), and twenty age and gender-related ophthalmologically healthy control subjects (C) during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD) critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL) due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on the central area of the visual field than patients who failed the test. In addition, patients who passed the test performed more glances towards the area of their visual field defect. In conclusion, our findings support the hypothesis that the extent of visual field per se cannot predict driving fitness, because some patients with HVFDs and advanced glaucoma can compensate for their deficit by effective visual scanning. Head movements appeared to be superior to eye and shoulder movements in predicting the outcome of the driving test under the present study scenario.
PMCID: PMC3921141  PMID: 24523869
3.  Prediction of On-Road Driving Performance in Patients with Early Alzheimer’s Disease 
Physicians and family members frequently are asked to provide information about driving ability in patients with Alzheimer’s disease (AD), yet there has been little research on the validity of their assessments of driving performance.
Participants were recruited from the neurology department of a community hospital affiliated with Brown Medical School.
Participants included 75 older adults (17 with mild AD, 33 with very mild AD, and 25 elderly controls).
The participant him/herself, an informant, and an experienced neurologist rated each participant’s driving ability on a 3-point rating scale (safe, marginal, unsafe). A professional driving instructor also completed a standardized 108-point on-road driving assessment of each participant and then rated driving ability on the 3-point scale. Ratings were compared with the on-road driving score and with each other.
Only the neurologist’s rating of the participants’ driving abilities was significantly related to on-road driving score. When related to the instructor’s safety rating, the neurologist’s ratings were the most sensitive and specific. Mini-Mental State Examination score was a borderline covariate for the neurologist’s rating. Overall, the instructor was the most stringent rater of participant driving ability, followed by the neurologist, the informant, and the participant.
An experienced neurologist’s assessment of driving competence may be a valid predictor of driving performance of patients with early AD.
PMCID: PMC3292197  PMID: 15667383
dementia; driving; assessment; Alzheimer’s disease
4.  Neuropsychological deficits associated with driving performance in Parkinson’s and Alzheimer’s disease 
Neuropsychological and motor deficits in Parkinson’s disease that may contribute to driving impairment were examined in a cohort study comparing patients with Parkinson’s disease (PD) to patients with Alzheimer’s disease (AD) and to healthy elderly controls. Nondemented individuals with Parkinson’s disease [Hoehn & Yahr (H&Y) stage I–III], patients with Alzheimer’s disease [Clinical Demetia Rating scale (CDR) range 0–1], and elderly controls, who were actively driving, completed a neuropsychological battery and a standardized road test administered by a professional driving instructor. On-road driving ability was rated on number of driving errors and a global rating of safe, marginal, or unsafe. Overall, Alzheimer’s patients were more impaired drivers than Parkinson’s patients. Parkinson’s patients distinguished themselves from other drivers by a head-turning deficiency. Drivers with neuropsychological impairment were more likely to be unsafe drivers in both disease groups compared to controls. Compared to controls, unsafe drivers with Alzheimer’s disease were impaired across all neuropsychological measures except finger tapping. Driving performance in Parkinson’s patients was related to disease severity (H&Y), neuropsychological measures [Rey Osterreith Complex Figure (ROCF), Trails B, Hopkins Verbal List Learning Test (HVLT)-delay], and specific motor symptoms (axial rigidity, postural instability), but not to the Unified Parkinson Disease Rating Scale (UPDRS) motor score. Multifactorial measures (ROCF, Trails B) were useful in distinguishing safe from unsafe drivers in both patient groups.
PMCID: PMC3292203  PMID: 16248912
Dementia; Motor vehicles; Cognition; Memory; Neurodegenerative diseases; Basal ganglia
5.  Computerized Maze Navigation and On-Road Performance by Drivers With Dementia 
This study examined the ability of computerized maze test performance to predict the road test performance of cognitively impaired and normal older drivers. The authors examined 133 older drivers, including 65 with probable Alzheimer disease, 23 with possible Alzheimer disease, and 45 control subjects without cognitive impairment. Subjects completed 5 computerized maze tasks employing a touch screen and pointer as well as a battery of standard neuropsychological tests. Parameters measured for mazes included errors, planning time, drawing time, and total time. Within 2 weeks, subjects were examined by a professional driving instructor on a standardized road test modeled after the Washington University Road Test. Road test total score was significantly correlated with total time across the 5 mazes. This maze score was significant for both Alzheimer disease subjects and control subjects. One maze in particular, requiring less than 2 minutes to complete, was highly correlated with driving performance. For the standard neuropsychological tests, highest correlations were seen with Trail Making A (TrailsA) and the Hopkins Verbal Learning Tests Trial 1 (HVLT1). Multiple regression models for road test score using stepwise subtraction of maze and neuropsychological test variables revealed significant independent contributions for total maze time, HVLT1, and TrailsA for the entire group; total maze time and HVLT1 for Alzheimer disease subjects; and TrailsA for normal subjects. As a visual analog of driving, a brief computerized test of maze navigation time compares well to standard neuropsychological tests of psychomotor speed, scanning, attention, and working memory as a predictor of driving performance by persons with early Alzheimer disease and normal elders. Measurement of maze task performance appears to be useful in the assessment of older drivers at risk for hazardous driving.
PMCID: PMC3292182  PMID: 18287166
driving; dementia; mild cognitive impairment; maze; computerized assessment
6.  Prediction of Fitness to Drive in Patients with Alzheimer's Dementia 
PLoS ONE  2016;11(2):e0149566.
The number of patients with Alzheimer’s disease (AD) is increasing and so is the number of patients driving a car. To enable patients to retain their mobility while at the same time not endangering public safety, each patient should be assessed for fitness to drive. The aim of this study is to develop a method to assess fitness to drive in a clinical setting, using three types of assessments, i.e. clinical interviews, neuropsychological assessment and driving simulator rides. The goals are (1) to determine for each type of assessment which combination of measures is most predictive for on-road driving performance, (2) to compare the predictive value of clinical interviews, neuropsychological assessment and driving simulator evaluation and (3) to determine which combination of these assessments provides the best prediction of fitness to drive. Eighty-one patients with AD and 45 healthy individuals participated. All participated in a clinical interview, and were administered a neuropsychological test battery and a driving simulator ride (predictors). The criterion fitness to drive was determined in an on-road driving assessment by experts of the CBR Dutch driving test organisation according to their official protocol. The validity of the predictors to determine fitness to drive was explored by means of logistic regression analyses, discriminant function analyses, as well as receiver operating curve analyses. We found that all three types of assessments are predictive of on-road driving performance. Neuropsychological assessment had the highest classification accuracy followed by driving simulator rides and clinical interviews. However, combining all three types of assessments yielded the best prediction for fitness to drive in patients with AD with an overall accuracy of 92.7%, which makes this method highly valid for assessing fitness to drive in AD. This method may be used to advise patients with AD and their family members about fitness to drive.
PMCID: PMC4766198  PMID: 26910535
7.  Cognitive deficits are associated with poorer simulated driving in older adults with heart failure 
BMC Geriatrics  2013;13:58.
Cognitive impairment is prevalent in older adults with heart failure (HF) and associated with reduced functional independence. HF patients appear at risk for reduced driving ability, as past work in other medical samples has shown cognitive dysfunction to be an important contributor to driving performance. The current study examined whether cognitive dysfunction was independently associated with reduced driving simulation performance in a sample of HF patients.
18 persons with HF (67.72; SD = 8.56 year) completed echocardiogram and a brief neuropsychological test battery assessing global cognitive function, attention/executive function, memory and motor function. All participants then completed the Kent Multidimensional Assessment Driving Simulation (K-MADS), a driving simulator scenario with good psychometric properties.
The sample exhibited an average Mini Mental State Examination (MMSE) score of 27.83 (SD = 2.09). Independent sample t-tests showed that HF patients performed worse than healthy adults on the driving simulation scenario. Finally, partial correlations showed worse attention/executive and motor function were independently associated with poorer driving simulation performance across several indices reflective of driving ability (i.e., centerline crossings, number of collisions, % of time over the speed limit, among others).
The current findings showed that reduced cognitive function was associated with poor simulated driving performance in older adults with HF. If replicated using behind-the-wheel testing, HF patients may be at elevated risk for unsafe driving and routine driving evaluations in this population may be warranted.
PMCID: PMC3681599  PMID: 24499466
Driving simulation; Heart failure; Cognitive function; Driving ability
8.  Visual and cognitive predictors of driving safety in Parkinson's disease patients 
This study assessed the clinical utility of contrast sensitivity (CS) relative to attention, executive function, and visuospatial abilities for predicting driving safety in participants with Parkinson's disease (PD). Twenty-five, non-demented PD patients completed measures of contrast sensitivity, visuospatial skills, executive functions, and attention. All PD participants also underwent a formal on-road driving evaluation. Of the 25 participants, 11 received a marginal or unsafe rating on the road test. Poorer driving performance was associated with worse performance on measures of CS, visuospatial constructions, set shifting, and attention. While impaired driving was associated with a range of cognitive and visual abilities, only a composite measure of executive functioning and visuospatial abilities, and not CS or attentional skills, predicted driving performance. These findings suggest that neuropsychological tests, which are multifactorial in nature and require visual perception and visual spatial judgments are the most useful screening measures for hazardous driving in PD patients.
PMCID: PMC3555123  PMID: 17851032
Contrast sensitivity; Executive function; Visuospatial; Activities of daily living
9.  Road Test and Naturalistic Driving Performance in Healthy and Cognitively Impaired Older Adults: Does Environment Matter? 
The road test is regarded as the gold standard for determining driving competence in older adults, but it is unclear how well the road test relates to naturalistic driving. The study objective was to relate the standardized road test to video recordings of naturalistic driving in older adults with a range of cognitive impairment.
Cross-sectional observational study.
Academic medical center memory disorders clinic.
103 older drivers (44 healthy and 59 with cognitive impairment) who passed a road test.
Error rate and global ratings of safety (pass with and without recommendations, marginal with restrictions or training, or fail) made by a professional driving instructor.
There was fair agreement between global ratings on the road test and naturalistic driving. More errors were detected in the naturalistic environment, but this did not impact global ratings. Error scores between settings were significantly correlated, and the types of errors made were similar. History of crashes corrected for miles driven per week was related to road test error scores, but not naturalistic driving error scores. Global cognition (MMSE) was correlated with both road test and naturalistic driving errors. In the healthy older adults, younger age was correlated with fewer errors on the road test and greater errors in naturalistic driving.
Road test performance is a reasonable proxy for estimating fitness to drive in older individuals’ typical driving environments. The differences between performance assessed by these two methods, however, remain poorly understood and deserve further study.
PMCID: PMC3498523  PMID: 23110378
driving; dementia; naturalistic; assessment
10.  Clinician Assessment of the Driving Competence of Patients with Dementia 
To determine the validity and reliability of clinician ratings of the driving competence of patients with mild dementia.
Observational study of a cross-section of drivers with mild dementia based on chart review by clinicians with varying types of expertise and experience.
Outpatient dementia clinic.
Fifty dementia subjects from a longitudinal study of driving and dementia.
Each clinician reviewed information from the clinic charts and the first study visit. The clinician then rated the drivers as safe, marginal, or unsafe. A professional driving instructor compared these ratings with total driving scores on a standardized road test and categorical ratings of driving competence. Clinicians also completed a visual analog scale assessment of variables that led to their determinations of driving competence.
Accuracy of clinician ratings ranged from 62% to 78% for the instructor’s global rating of safe versus marginal or unsafe. In general, there was moderate accuracy and interrater reliability. Accuracy could have been improved in the least-accurate raters by greater attention to dementia duration and severity ratings, as well as less reliance on the history and physical examination. The most accurate predictors were clinicians specially trained in dementia assessment, who were not necessarily the most experienced in their years of clinical experience.
Although a clinician may be able to identify many potentially hazardous drivers, accuracy is insufficient to suggest that a clinician’s assessment alone is adequate to determine driving competence in those with mild dementia.
PMCID: PMC3292185  PMID: 15877559
dementia; driving; Alzheimer’s disease
11.  Naturalistic Validation of an On-Road Driving Test of Older Drivers 
Human factors  2012;54(4):663-674.
The objective was to compare a standardized road test to naturalistic driving by older people who may have cognitive impairment to define improvements that could potentially enhance the validity of road testing in this population.
Road testing has been widely adapted as a tool to assess driving competence of older people who may be at risk for unsafe driving because of dementia; however, the validity of this approach has not been rigorously evaluated.
For 2 weeks, 80 older drivers (38 healthy elders and 42 with cognitive impairment) who passed a standardized road test were video recorded in their own vehicles. Using a standardized rating scale, 4 hr of video was rated by a driving instructor. The authors examine weighting of individual road test items to form global impressions and to compare road test and naturalistic driving using factor analyses of these two assessments.
The road test score was unidimensional, reflecting a major factor related to awareness of signage and traffic behavior. Naturalistic driving reflected two factors related to lane keeping as well as traffic behavior.
Maintenance of proper lane is an important dimension of driving safety that appears to be relatively underemphasized during the highly supervised procedures of the standardized road test.
Road testing in this population could be improved by standardized designs that emphasize lane keeping and that include self-directed driving. Additional information should be sought from observers in the community as well as crash evidence when advising older drivers who may be cognitively impaired.
PMCID: PMC3568996  PMID: 22908688
driving; aging; dementia; Alzheimer’s disease; cognitive impairment
12.  Neuropsychological Assessment of Driving Safety Risk in Older Adults With and Without Neurologic Disease 
Decline in cognitive abilities can be an important contributor to the driving problems encountered by older adults, and neuropsychological assessment may provide a practical approach to evaluating this aspect of driving safety risk. The purpose of the present study was to evaluate several commonly used neuropsychological tests in the assessment of driving safety risk in older adults with and without neurological disease. A further goal of this study was to identify brief combinations of neuropsychological tests that sample performances in key functional domains and thus could be used to efficiently assess driving safety risk. 345 legally licensed and active drivers over the age of 50, with either no neurologic disease (N=185), probable Alzheimer's disease (N=40), Parkinson's disease (N=91), or stroke (N=29), completed vision testing, a battery of 10 neuropsychological tests, and an 18 mile drive on urban and rural roads in an instrumented vehicle. Performances on all neuropsychological tests were significantly correlated with driving safety errors. Confirmatory factor analysis was used to identify 3 key cognitive domains assessed by the tests (speed of processing, visuospatial abilities, and memory), and several brief batteries consisting of one test from each domain showed moderate corrected correlations with driving performance. These findings are consistent with the notion that driving places demands on multiple cognitive abilities that can be affected by aging and age-related neurological disease, and that neuropsychological assessment may provide a practical off-road window into the functional status of these cognitive systems.
PMCID: PMC3910382  PMID: 22943767
13.  Can a Novel Web-Based Computer Test Predict Poor Simulated Driving Performance? A Pilot Study With Healthy and Cognitive-Impaired Participants 
Driving a car is a complex instrumental activity of daily living and driving performance is very sensitive to cognitive impairment. The assessment of driving-relevant cognition in older drivers is challenging and requires reliable and valid tests with good sensitivity and specificity to predict safe driving. Driving simulators can be used to test fitness to drive. Several studies have found strong correlation between driving simulator performance and on-the-road driving. However, access to driving simulators is restricted to specialists and simulators are too expensive, large, and complex to allow easy access to older drivers or physicians advising them. An easily accessible, Web-based, cognitive screening test could offer a solution to this problem. The World Wide Web allows easy dissemination of the test software and implementation of the scoring algorithm on a central server, allowing generation of a dynamically growing database with normative values and ensures that all users have access to the same up-to-date normative values.
In this pilot study, we present the novel Web-based Bern Cognitive Screening Test (wBCST) and investigate whether it can predict poor simulated driving performance in healthy and cognitive-impaired participants.
The wBCST performance and simulated driving performance have been analyzed in 26 healthy younger and 44 healthy older participants as well as in 10 older participants with cognitive impairment. Correlations between the two tests were calculated. Also, simulated driving performance was used to group the participants into good performers (n=70) and poor performers (n=10). A receiver-operating characteristic analysis was calculated to determine sensitivity and specificity of the wBCST in predicting simulated driving performance.
The mean wBCST score of the participants with poor simulated driving performance was reduced by 52%, compared to participants with good simulated driving performance (P<.001). The area under the receiver-operating characteristic curve was 0.80 with a 95% confidence interval 0.68-0.92.
When selecting a 75% test score as the cutoff, the novel test has 83% sensitivity, 70% specificity, and 81% efficiency, which are good values for a screening test. Overall, in this pilot study, the novel Web-based computer test appears to be a promising tool for supporting clinicians in fitness-to-drive assessments of older drivers. The Web-based distribution and scoring on a central computer will facilitate further evaluation of the novel test setup. We expect that in the near future, Web-based computer tests will become a valid and reliable tool for clinicians, for example, when assessing fitness to drive in older drivers.
PMCID: PMC3806521  PMID: 24144946
cognitive impairment; Web-based cognitive test; computer-based tests; driving simulation
14.  Decreased driving ability in people with Parkinson's disease 
BACKGROUND—Driving is a complex form of activity involving especially cognitive and psychomotor functions. These functions may be impaired by Parkinson's disease. The relation between Parkinson's disease and driving ability is still obscure and clinicians have to make decisions concerning the driving ability of their patients based on insufficent information. Until now no studies have compared different methods for evaluating the driving ability of patients with Parkinson's disease.
METHODS—The driving ability of 20 patients with idiopathic Parkinson's disease and 20 age and sex matched healthy control subjects was evaluated by a neurologist, psychologist, vocational rehabilitation counsellor, and driving instructor using a standard 10 point scale. The patients and controls also evaluated their own driving ability. Cognitive and psychomotor laboratory tests and a structured on road driving test were used for evaluating the subjects' driving ability.
RESULTS—The patients with Parkinson's disease performed worse than the controls both in the laboratory tests and in the driving test. There was a high correlation between the laboratory tests and driving test both in the patient group and in the control group. Disease indices were not associated with the driving test. The neurologist overestimated the ability of patients with Parkinson's disease to drive compared with the driving ability evaluated by the structured on road driving test and with the driving related laboratory tests. Patients themselves were not capable of evaluating their own ability reliably.
CONCLUSION—Driving ability is greatly decreased in patients with even mild to moderate Parkinson's disease. The evaluation of patients' driving ability is very difficult to carry out without psychological and psychomotor tests and/or a driving test.

PMCID: PMC2170019  PMID: 9527142
15.  Quantitative assessment of driving performance in Parkinson's disease 
Objectives: The primary aim of this study was to determine how Parkinson's disease (PD) affects driving performance. It also examined whether changes in driver safety were related to specific clinical disease markers or an individual's self rating of driving ability.
Methods: The driving performance of 25 patients with idiopathic PD and 21 age matched controls was assessed on a standardised open road route by an occupational therapist and driving instructor, to provide overall safety ratings and specific driving error scores.
Results: The drivers with PD were rated as significantly less safe (p<0.05) than controls, and more than half of the drivers with PD would not have passed a state based driving test. The driver safety ratings were more strongly related to disease duration (r = –0.60) than to their on time Unified Parkinson's Disease Rating Scale (r = –0.24). Drivers with PD made significantly more errors than the control group during manoeuvres that involved changing lanes and lane keeping, monitoring their blind spot, reversing, car parking, and traffic light controlled intersections. The driving instructor also had to intervene to avoid an incident significantly more often for drivers with PD than for controls. Interestingly, driver safety ratings were unrelated to an individual's rating of their own driving performance, and this was the case for all participants.
Conclusions: As a group, drivers with PD are less safe to drive than age matched controls. Standard clinical markers cannot reliably predict driver safety. Further studies are required to ascertain whether the identified driving difficulties can be ameliorated.
PMCID: PMC1739510  PMID: 15654027
16.  Comparison of assessments of fitness to drive for people with dementia 
Neuropsychological Rehabilitation  2014;24(5):770-783.
Cognitive tests are used to inform recommendations about the fitness to drive of people with dementia. The Rookwood Driving Battery (RDB) and Dementia Drivers' Screening Assessment (DDSA) are neuropsychological batteries designed to assist in this process. The aim was to assess the concordance between the classifications (pass/fail) of the RDB and DDSA in individuals with dementia, and to compare any discordant classifications against on-road driving ability. Participants were identified by community mental health teams and psychiatrists. Twenty four participants were recruited. The mean age was 74.1 (SD 8.9) years and 18 (75%) were men. Each participant was assessed on the RDB and DDSA in an order determined by random allocation. Those with discrepant results also had an on-road assessment. The agreement between the tests was 54% using a cut-off of > 6 on the RDB, and 75% using the cut-off to > 10 on the RDB. Three participants with discrepant results agreed to be assessed on the road and all were found to be safe to drive. The findings suggested that there was poor concurrent validity between the RDB and DDSA. This raises questions about the choice of assessments in making clinical recommendations about fitness to drive in people with dementia.
PMCID: PMC4151795  PMID: 24801811
Cognition; Driving; Dementia; Assessment
17.  A Longitudinal Study of Drivers with Alzheimer Disease 
Neurology  2008;70(14):1171-1178.
The goal of this study was to define the natural progression of driving impairment in persons who initially have very mild to mild dementia.
We studied 128 older drivers, including 84 with early Alzheimer’s disease (AD) and 44 age-matched control subjects without cognitive impairment. Subjects underwent repeated assessments of their cognitive, neurological, visual and physical function over three years. Self-reports of driving accidents and traffic violations were supplemented by reports from family informants and state records. Within two weeks of the office evaluation, subjects were examined by a professional driving instructor on a standardized road test.
At baseline, AD subjects had experienced more accidents and performed more poorly on the road test, compared to controls. Over time, both groups declined in driving performance on the road test, with AD subjects declining more than controls. Survival analysis indicated that while the majority of subjects with AD passed the examination at baseline, greater severity of dementia, increased age, and lower education were associated with higher rates of failure and marginal performance.
This study confirms previous reports of potentially hazardous driving in persons with early AD, but also indicates that some individuals with very mild dementia can continue to drive safely for extended periods of time. Regular followup assessments, however, are warranted in those individuals.
PMCID: PMC3664938  PMID: 18216302
18.  Predicting Road Test Performance in Drivers with Dementia 
To develop a cognitive and functional screening battery for the on-road performance of older drivers with dementia.
A prospective observational study.
On-road driving evaluation clinic at an academic rehabilitation center
Ninety-nine older people with dementia (63% male, mean age = 74.2 years, SD= 9), referred by community physicians to an Occupational Therapy driving clinic.
The outcome variable was pass/fail on the modified Washington University Road Test. Predictor measures were tests of visual, motor and cognitive functioning, selected for their empirical or conceptual relationship to the complex task of driving safely.
Sixty-five (65%) of participants failed the on-road driving test. The best predictive model, with an overall accuracy of up to 85% when participants were blinded, included AD-8 score, the Clock Drawing Test score, and the time to complete either the Snellgrove Maze Test (SMT) or Trail Making Test A. Visual and motor functioning were not associated with road driving test failure.
A screening battery that could be performed in less than 10 minutes predicted with good accuracy a failure rating on the on-road driving test in this sample of older drivers with dementia. A “probability of failure” calculator is provided from a logistic regression model that may be useful for clinicians in their decision to refer impaired older adults for further testing. More studies are needed in larger community based samples, along with discussions with patients, families and clinicians, in regards to acceptable levels of test uncertainty.
PMCID: PMC3228409  PMID: 22092029
on-road driving safety; dementia; older drivers
19.  Diagnostic Accuracy Statistics for Seven Neuropsychological Assessment Battery (NAB) Test Variables in the Diagnosis of Alzheimer’s Disease 
Applied neuropsychology. Adult  2012;19(2):10.1080/09084282.2011.643947.
Neuropsychological tests are useful for diagnosing Alzheimer’s disease (AD), yet for many tests, diagnostic accuracy statistics are unavailable. We present diagnostic accuracy statistics for seven variables from the Neuropsychological Assessment Battery (NAB) that were administered to a large sample of elderly adults (n = 276) participating in a longitudinal research study at a national AD Center. Tests included Driving Scenes, Bill Payment, Daily Living Memory, Screening Visual Discrimination, Screening Design Construction, and Judgment. Clinical diagnosis was made independent of these tests, and for the current study, participants were categorized as AD (n = 65) or non-AD (n = 211). Receiver operating characteristics curve analysis was used to determine each test’s sensitivity and specificity at multiple cut points, which were subsequently used to calculate positive and negative predictive values at a variety of base rates. Of the tests analyzed, the Daily Living Memory test provided the greatest accuracy in the identification of AD and the two Screening measures required a significant tradeoff between sensitivity and specificity. Overall, the seven NAB subtests included in the current study are capable of excellent diagnostic accuracy, but appropriate understanding of the context in which the tests are used is crucial for minimizing errors.
PMCID: PMC3857936  PMID: 23373577
20.  Practice Parameter update: Evaluation and management of driving risk in dementia 
Neurology  2010;74(16):1316-1324.
To review the evidence regarding the usefulness of patient demographic characteristics, driving history, and cognitive testing in predicting driving capability among patients with dementia and to determine the efficacy of driving risk reduction strategies.
Systematic review of the literature using the American Academy of Neurology's evidence-based methods.
For patients with dementia, consider the following characteristics useful for identifying patients at increased risk for unsafe driving: the Clinical Dementia Rating scale (Level A), a caregiver's rating of a patient's driving ability as marginal or unsafe (Level B), a history of crashes or traffic citations (Level C), reduced driving mileage or self-reported situational avoidance (Level C), Mini-Mental State Examination scores of 24 or less (Level C), and aggressive or impulsive personality characteristics (Level C). Consider the following characteristics not useful for identifying patients at increased risk for unsafe driving: a patient's self-rating of safe driving ability (Level A) and lack of situational avoidance (Level C). There is insufficient evidence to support or refute the benefit of neuropsychological testing, after controlling for the presence and severity of dementia, or interventional strategies for drivers with dementia (Level U).
= American Academy of Neurology;
= Alzheimer disease;
= Clinical Dementia Rating;
= confidence interval;
= Mini-Mental State Examination;
= odds ratio;
= on-road driving test;
= Quality Standards Subcommittee;
= relative risk.
PMCID: PMC2860481  PMID: 20385882
21.  Accuracy of the DriveABLE cognitive assessment to determine cognitive fitness to drive 
Canadian Family Physician  2013;59(3):e156-e161.
To evaluate the accuracy of the DriveABLE In-Office cognitive assessment in predicting cognitively impaired drivers’ performance on the DriveABLE On-Road Evaluation (DORE).
Retrospective study comparing data from DriveABLE In-Office cognitive assessment outcomes with DORE outcomes.
Nineteen of the locations in North America providing the DriveABLE assessment between the years 2007 and 2010.
Database records from 3662 patients (2639 men, mean age 74.1 years, range 18 to 99 years of age; 1023 women, mean age 73.5 years, range 18 to 94 years of age) with suspected or confirmed cognitive impairment. All patients were referred for DriveABLE evaluation and received both the In-Office cognitive assessment and, regardless of the In-Office test results, the DORE. This is a subset of the database because typically the DriveABLE In-Office cognitive assessment serves as the cognitive assessment and only those whose results are in the indeterminate range go on to complete the road test (ie, DORE).
Main outcome measures
Accuracy of the In-Office assessment for predicting the outcome of the DORE.
For the total sample, the error rate for predicting actual performance on the road test was 1.7% for pass predictions and 5.6% for fail predictions. Notably, these low error rates were consistent across the 4 years. On the basis of performance on the In-Office cognitive assessment, pass or fail decisions could have been made for more than half of the referrals, reducing the need to take dangerous drivers on the road and reducing the cost of the assessment process for patients and the system.
The accuracy of the DriveABLE In-Office cognitive assessment was evaluated in the context of normal clinical referral processes, with a large sample of referrals during a 4-year period and from multiple sites. The high and stable accuracy rates provide the evidence physicians need to be confident in using the recommendations from the DriveABLE cognitive evaluation to assist them in making evidence-based decisions about their patients’ ability to continue driving.
PMCID: PMC3596225  PMID: 23486817
22.  Predictors of Driving Outcomes in Advancing Age 
Psychology and aging  2011;27(3):550-559.
This study aimed to develop predictive models for real-life driving outcomes in older drivers. Demographics, driving history, on-road driving errors, and performance on visual, motor, and neuropsychological test scores at baseline were assessed in 100 older drivers (ages 65–89 years [72.7]). These variables were used to predict time to driving cessation, first moving violation, or crash. Using Cox proportional hazards regression models, significant individual predictors for driving cessation were greater age and poorer scores on Near Visual Acuity, Contrast Sensitivity, Useful Field of View, Judgment of Line Orientation, Trail Making Test-Part A, Benton Visual Retention Test, Grooved Pegboard, and a composite index of overall cognitive ability. Greater weekly mileage, higher education, and “serious” on-road errors predicted moving violations. Poorer scores from Trail Making Test-Part B or Trail Making Test (B-A) and serious on-road errors predicted crashes. Multivariate models using “off-road” predictors revealed (1) age and Contrast Sensitivity as best predictors for driving cessation; (2) education, weekly mileage, and Auditory Verbal Learning Task-Recall for moving violations; and (3) education, number of crashes over the past year, Auditory Verbal Learning Task-Recall, and Trail Making Test (B-A) for crashes. Diminished visual, motor, and cognitive abilities in older drivers can be easily and noninvasively monitored with standardized off-road tests, and performances on these measures predict involvement in motor vehicle crashes and driving cessation, even in the absence of a neurological disorder.
PMCID: PMC3360997  PMID: 22182364
neuropsychological tests; safety errors; driving cessation; instrumented vehicle
23.  Foggy perception slows us down 
eLife  2012;1:e00031.
Visual speed is believed to be underestimated at low contrast, which has been proposed as an explanation of excessive driving speed in fog. Combining psychophysics measurements and driving simulation, we confirm that speed is underestimated when contrast is reduced uniformly for all objects of the visual scene independently of their distance from the viewer. However, we show that when contrast is reduced more for distant objects, as is the case in real fog, visual speed is actually overestimated, prompting drivers to decelerate. Using an artificial anti-fog—that is, fog characterized by better visibility for distant than for close objects, we demonstrate for the first time that perceived speed depends on the spatial distribution of contrast over the visual scene rather than the global level of contrast per se. Our results cast new light on how reduced visibility conditions affect perceived speed, providing important insight into the human visual system.
eLife digest
The ways people respond to conditions of reduced visibility is a central topic in vision research. Notably, it has been shown that people tend to underestimate speeds when visibility is reduced equally at all distances, as for example, when driving with a fogged up windshield. But what happens when the visibility decreases as you look further into the distance, as happens when driving in fog? Fortunately, as new research reveals, people tend to overestimate their speed when driving in fog-like conditions, and show a natural tendency to drive at a slower pace.
Pretto et al. performed a series of experiments involving experienced drivers and high-quality virtual reality simulations. In one experiment, drivers were presented with two driving scenes and asked to guess which scene was moving faster. In the reference scene, the car was driving at a fixed speed through a landscape under conditions of clear visibility; in the test scene, it was moving through the same landscape, again at a fixed speed, but with the visibility reduced in different ways. The experiments showed that drivers overestimated speeds in fog-like conditions, and they underestimated speeds when the reduction in visibility did not depend on distance. Further experiments confirmed that these perceptions had an influence on driving behaviour: drivers recorded an average speed of 85.1 km/hr when the visibility was good, and this dropped to 70.9 km/hr in severe fog. However, when visibility was reduced equally at all distances, as happens with a fogged up windshield, the average driving speed increased to 101.3 km/hr.
Based on previous work, Pretto et al. developed the theory that the perception of speed is influenced by the relative speeds of the visible regions in the scene. When looking directly into the fog, visibility is strongly reduced in the distant regions, where the relative motion is slow, and is preserved in the near regions, where the motion is fast. This visibility gradient would lead to speed overestimation. To test this theory, the experiments were repeated with new drivers under three different conditions: good visibility, fog, and an artificial situation called ‘anti-fog’ in which visibility is poor in the near regions and improves as the driver looks further into the distance. As predicted, the estimated speed was lower in anti-fog than in clear visibility and fog. Conversely, the driving speed was 104.4 km/hr in anti-fog compared with 67.9 km/hr in good visibility and 51.3 km/hr in fog.
Overall, the results show that the perception of speed is influenced by spatial variations in visibility, and they strongly suggest that this is due to the relative speed contrast between the visible and covert areas within the scene.
PMCID: PMC3479833  PMID: 23110253
motion perception; human psychophysics; virtual reality; driving simulation; Human
24.  Driving Cessation and Dementia: Results of the Prospective Registry on Dementia in Austria (PRODEM) 
PLoS ONE  2012;7(12):e52710.
To assess the influence of cognitive, functional and behavioral factors, co-morbidities as well as caregiver characteristics on driving cessation in dementia patients.
The study cohort consists of those 240 dementia cases of the ongoing prospective registry on dementia in Austria (PRODEM) who were former or current car-drivers (mean age 74.2 (±8.8) years, 39.6% females, 80.8% Alzheimer’s disease). Reasons for driving cessation were assessed with the patients’ caregivers. Standardized questionnaires were used to evaluate patient- and caregiver characteristics. Cognitive functioning was determined by Mini-Mental State Examination (MMSE), the CERAD neuropsychological test battery and Clinical Dementia Rating (CDR), activities of daily living (ADL) by the Disability Assessment for Dementia, behavior by the Neuropsychiatric Inventory (NPI) and caregiver burden by the Zarit burden scale.
Among subjects who had ceased driving, 136 (93.8%) did so because of “Unacceptable risk” according to caregiver’s judgment. Car accidents and revocation of the driving license were responsible in 8 (5.5%) and 1(0.7%) participant, respectively. Female gender (OR 5.057; 95%CI 1.803–14.180; p = 0.002), constructional abilities (OR 0.611; 95%CI 0.445–0.839; p = 0.002) and impairment in Activities of Daily Living (OR 0.941; 95%CI 0.911–0.973; p<0.001) were the only significant and independent associates of driving cessation. In multivariate analysis none of the currently proposed screening tools for assessment of fitness to drive in elderly subjects including the MMSE and CDR were significantly associated with driving cessation.
The risk-estimate of caregivers, but not car accidents or revocation of the driving license determines if dementia patients cease driving. Female gender and increasing impairment in constructional abilities and ADL raise the probability for driving cessation. If any of these factors also relates to undesired traffic situations needs to be determined before recommendations for their inclusion into practice parameters for the assessment of driving abilities in the elderly can be derived from our data.
PMCID: PMC3530518  PMID: 23300746
25.  Neuropsychological Predictors of Driving Errors in Older Adults 
To identify neuropsychological factors associated with driving errors in older adults.
Cross-sectional observational study.
Neuropsychological assessment laboratory and an instrumented vehicle on a 35-mile route on urban and rural roads.
One hundred eleven older adult drivers (ages 65-89 years; mean age 72.3 years) and 80 middle-aged drivers (age 40 to 64 years; mean age 57.2 years).
Explanatory variables included age, neuropsychological measures (cognitive, visual, and motor), and a composite cognitive score (COGSTAT). The outcome variable was the safety error count, as classified by video review using a standardized taxonomy.
Older drivers committed an average of 35.8 safety errors/drive (SD=12.8), compared to an average of 28.8 (SD=9.8) for middle-age drivers (P<0.001). Among older drivers, there was an increase of 2.6 errors per drive observed for each five-year age increase (P=0.026). After adjustment for age, education, and gender, COGSTAT was a significant predictor of safety errors in older drivers (P=0.005), with approximately a 10% increase in safety errors observed for a 10% decrease in cognitive function. Individual significant predictors of increased safety errors in older drivers included poorer scores on Complex Figure Test-Copy, Complex Figure Test-Recall, Block Design, Near Visual Acuity, and the Grooved Pegboard task.
Driving errors in older adults tend to increase, even in the absence of neurological diagnoses. Some of this increase can be explained by age-related decline in cognitive abilities, vision, and motor skills. Changes in visuospatial and visuomotor abilities appear to be particularly associated with unsafe driving in old age.
PMCID: PMC3204878  PMID: 20487082
Neuropsychological tests; cognitive decline; safety errors; instrumented vehicle

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