The effect of age on driving skills

Age-Related Effect of Sleepiness on Driving Performance: A Systematic-Review

Background: Several studies highlighted that sleepiness affects driving abilities. In particular, road traffic injuries due to excessive daytime sleepiness are about 10–20%. Considering that aging is related to substantial sleep changes and the number of older adults with driving license is increasing, the current review aims to summarize recent studies on this issue. Further, we intend to provide insights for future research. Methods: From the 717 records screened, ten articles were selected and systematically reviewed. Results: Among the selected articles, (a) five studies investigated sleepiness only by self-reported standardized measures; (b) two studies assessed sleepiness also using a behavioral task; (c) three studies obtained objective measures by electroencephalographic recordings. Conclusions: The available literature on the topic reports several limitations. Overall, many findings converge in evidencing that older drivers are less vulnerable to sleep loss and sleepiness-related driving impairments than young adults. These discrepancies in sleepiness vulnerability between age groups may be ascribed to differences in subjects’ lifestyles. Moreover, it has been hypothesized that older adults self-regulate their driving and avoid specific dangerous situations. We believe that an easy protocol to objectively evaluate the vigilance level in elderly and young adults is required, and further studies are needed.

Analyzing driver behavior under naturalistic driving conditions: A review

For a decade, researchers working in the area of road safety have started exploring the use of driving behavior data for a better understanding of the causes related to road accidents. A review of the literature reveals the excellent potential of naturalistic driving studies carried out by collecting vehicle performance data and driver behavior data during normal, impaired, and safety-critical situations. An in-depth understanding of driver behavior helps analyze and implement pre-crash safety measures - the development of enforcement policies, infrastructure design, and intelligent vehicle safety systems. The present paper attempts to review the naturalistic driving studies that have been undertaken so far. The paper begins with an overview of different methods for collecting unobtrusive driver behavior data during their day to day trip, followed by a discussion of various factors affecting driving behavior and their influence on vehicle performance parameters. The paper also discusses the strategies mentioned in the literature for improving driving behavior using naturalistic driving studies to enhance road safety. Some of the major findings of this review suggest that i) driver behavior is a major cause in the majority of the road accidents ii) drivers generally reduce their speed and increases headway as a compensatory measure to reduce the workload imposed during distracting activity and adverse weather conditions iii) mobile phone has emerged as a potential device for collecting naturalistic driving data and, iv) improvement in driving behavior can be achieved by providing feedback to the drivers about their driving behavior. This can be done by implementing usage-based insurance schemes such as pay as you drive (PAYD), pay how you drive (PHYD), and manage how you drive (MHYD). While a considerable amount of research has been done to analyze driving behavior under naturalistic conditions, some areas which are yet to be explored are highlighted in the present paper.

Investigating the injury severity of single-vehicle truck crashes in a developing country

Trucking plays a vital role in economic development in every country, especially countries where it serves as the backbone of the economy. The fast growth of economy in Iran as a developing country has also been accompanied by an alarming situation in terms of fatalities in truck-involved crashes, among the drivers and passengers of the trucks as well as the other vehicles involved. Despite the sizable efforts to investigate the truck-involved crashes, very little is known about the safety of truck movements in developing countries, and about the single-truck crashes worldwide. Thus, this study aims to uncover significant factors associated with injury severities sustained by truck drivers in single-vehicle truck crashes in Iran. The explanatory factors tested in the models include the characteristics of drivers, vehicles, and roadways. A random threshold random parameters hierarchical ordered probit model is utilized to consider heterogeneity across observations. Several variables turned out to be significant in the model, including driver's education, advanced braking system deployment, presence of curves on roadways, and high speed-limit. Using those results, we propose safety countermeasures in three categories of 1) educational, 2) technological, and 3) road engineering to mitigate the severity of single-vehicle truck crashes.

Does Central Vision Loss Impair Visual Search Performance of Adults More than Children?

SIGNIFICANCE

In general, young adults with normal vision show the best visual search performance when compared with children and older adults. Through our study, we show that this trend is not observed in individuals with vision impairment. An interaction effect of vision impairment with visual development and aging is observed.

PURPOSE

Performance in many visual tasks typically shows improvement with age until young adulthood and then declines with aging. Using a visual search task, this study investigated whether a similar age effect on performance is present in people with central vision loss.

METHODS

A total of 98 participants, 37 with normal sight (NS) and 61 with visual impairment (VI) searched for targets in 150 real-world digital images. Search performance was quantified by an integrated measure combining speed and accuracy. Participant ages ranged from 5 to 74 years, visual acuity from -0.14 (20/14.5) to 1.16 logMAR (20/290), and log contrast sensitivity (CS) from 0.48 to 2.0. Data analysis was performed with participants divided into three age groups: children (aged <14 years, n = 25), young adults (aged 14 to 45 years, n = 47), and older adults (aged >45 years, n = 26).

RESULTS

Regression (r = 0.7) revealed CS (P < .001) and age (P = .003) were significant predictors of search performance. Performance of VI participants was normalized to the age-matched average performance of the NS group. In the VI group, it was found that children's normalized performance (52%) was better than both young (39%, P = .05) and older (40%, P = .048) adults.

CONCLUSIONS

Unlike NS participants, young adults in the VI group may not have search ability superior to children with VI, despite having the same level of visual functions (quantified by visual acuity and CS). This could be because of vision impairment limiting the developmental acquisition of the age dividend for peak performance. Older adults in the VI group had the worst performance, indicating an interaction of aging.

A simulated driving evaluation for patients with Alzheimer's disease

A prospective study concerning the driving ability of 41 patients with the diagnosis of Alzheimer's disease (AD) was performed. Using a simulated driving test we evaluated the predictive value of the MMSE,'4ADL,5-7and IADL&9to determine the ability of a person with Alzheimer's disease to drive. All patients were driving at the time of the evaluation.

There was no correlation between driving performance and functional status evaluated by ADL and IADL. When comparing driving performance with cognitive evaluation by MMSE, a significant number of patients with MMSE c 22failed the test, compared to patients with MMSE > 22 (P = 0.01, Fisher's exact test).

No patient with a MMSE < 20 passed the driving test. The authors recommend that health care professionals who are caring for people with Alzheimer's disease with a MMSE of22 or less should request a driving evaluation.

The “Co-pilot driveer syndrome:” A newly-reported driving habit in patients with Alzheimer's diseas

When should I take away the car keys? Is it still safe for him/her to drive? Are all patients diagnosed with Alzheimer's disease (AD) a hazard on the road? What about driving for short distances in a familiar territory? Can people with AD drive with family or caregiver supervision? Those are but a few of the difficult questions asked by caregivers of people with AD. There is confusion regarding the optimal time to recommend that a patient with AD stop driving.1-5 In an attempt to assist caregivers with this difficult question, guidelines have been issued, although they frequently have conflicting recommendations in this matter.6-10

Dual-task effects of simulated lane navigation and story recall in older adults with and without memory impairment

While driving is a complex task, it becomes relatively automatic over time although unfamiliar situations require increased cognitive effort. Much research has examined driving risk in cognitively impaired elders and found little effect. This study assessed whether mildly memory impaired elders made disproportionate errors in driving or story recall, under simultaneous simulated driving and story recall. Forty-six healthy (61% women; mean age = 76.4) and 15 memory impaired (66% women, mean age = 79.4) elders participated. Cognitive status was determined by neuropsychological performance. Results showed that during dual-task conditions, participants stayed in lane more, and recalled stories more poorly, than when they did the tasks separately. Follow-up analysis revealed that verbatim recall, in particular, was reduced while driving for healthy participants. While memory impaired participants performed more poorly than healthy controls on both tasks, cognitive status was not associated with greater dual-task costs when driving and story recall were combined.

Naturalistic validation of an on-road driving test of older drivers

OBJECTIVE

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.

BACKGROUND

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.

METHOD

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.

RESULTS

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.

CONCLUSION

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.

APPLICATION

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.

Fluctuating attentional demand in a simulated driving assessment: the roles of age and driving complexity

OBJECTIVE

The purpose of the study was to explore age differences in attentional demand in response to driving situations of varying complexity within the context of a simulated assessment protocol. It was hypothesized that as road complexity increased, an indicator of attentional demand (i.e., latency to respond to a secondary task) would increase and, independent of the road complexity, older adults would exhibit greater attentional demand in comparison with younger and middle-aged drivers.

METHODS

Drivers from 3 age categories (i.e., young, middle-aged, and older) completed an assessment protocol in a STISIM driving simulator (Systems Technology, Inc., Hawthorne, CA) during which participants responded to a series of strategically placed secondary tasks (i.e., peripheral detection tasks, PDTs). Situations where secondary tasks occurred were grouped according to whether they were straight-road, crossing-path, or lane-change events. Two global indices of driving safety as well as several cognitive measures external to the driving simulator were also collected.

RESULTS

The results supported the hypothesis in that complex driving situations elicited greater attentional demand among drivers of all ages. Older adults showed greater attentional demand in comparison to young and middle-aged adults even after controlling for baseline response time. Older drivers also scored poorer on a global measure of driving safety.

CONCLUSIONS

The findings are highly consistent with the literature on road complexity and attention that show that increased driving complexity is associated with poorer performance on tasks designed to concurrently assess attention, an effect that is more pronounced for older drivers. The results point to intrinsic and extrinsic factors that contribute to motor vehicle collisions (MVCs) among older drivers. The relevance of these findings is discussed in relation to interventions and future research aimed at improving road safety.

Does automatic transmission improve driving behavior in older drivers?

BACKGROUND

Most older drivers continue to drive as they age. To maintain safe and independent transport, mobility is important for all individuals, but especially for older drivers.

OBJECTIVE

The objective of this study was to investigate whether automatic transmission, compared with manual transmission, may improve the driving behavior of older drivers.

METHOD

In total, 31 older drivers (mean age 75.2 years) and 32 younger drivers - used as a control group (mean age 39.2 years) - were assessed twice on the same fixed route; once in a car with manual transmission and once in a car with automatic transmission. The cars were otherwise identical. The driving behavior was assessed with the Ryd On-Road Assessment driving protocol. Time to completion of left turns (right-hand side driving) and the impact of a distraction task were measured.

RESULTS

The older group had more driving errors than the younger group, in both the manual and the automatic transmission car. However, and contrary to the younger drivers, automatic transmission improved the older participants' driving behavior as demonstrated by safer speed adjustment in urban areas, greater maneuvering skills, safer lane position and driving in accordance with the speed regulations.

CONCLUSION

Switching to automatic transmission may be recommended for older drivers as a means to maintain safe driving and thereby the quality of their transport mobility.

Australian Occupational Therapy Driver Assessors’ Opinions on Improving On-Road Driver Assessment Procedures

OBJECTIVE. We collected practitioner opinions to improve the validity and reliability of the on-road driver assessment procedures used in Australia.

METHOD. We used focus groups to document the views of experienced occupational therapy driver assessors using a purposive sampling method.

RESULTS. Eight focus groups were conducted with 55 clinicians practicing in urban and rural regions. There was strong support for greater standardization of procedures for all tests. For drivers seeking unrestricted (open) licenses, use of standard routes with predetermined assessment points was important where practicable. Where use of a nonstandard route for this purpose was unavoidable, it was important to specify a minimum set of requirements related to route characteristics and assessment items.

CONCLUSION. Australian occupational therapy driver assessors support greater standardization of test routes and procedures to improve reliability and validity. However, the extent to which standardization can be achieved is limited by variable road traffic environments where assessments are conducted.

Effects of Alzheimer's disease and mild cognitive impairment on driving ability: a controlled clinical study by simulated driving test

OBJECTIVE

To assess the effects of Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI) on simulated car driving ability.

METHODS

Twenty patients with a probable AD of mild severity (Clinical Dementia Rating, CDR = 1) were compared with 20 subjects with MCI (CD = 0.5), and a group of age-matched neurologically normal controls on a driving simulation task. Measures of driving competence included the length of run, the number of infractions (omission of stop at pedestrian crossings, speed limits violation), the number of stops at traffic lights, the mean time to collision, and the number of off-road events. Results in the driving competence measures were correlated with scores obtained from simple visual reaction times and mini-mental state examination (MMSE).

RESULTS

The patients with mild AD performed significantly worse than MCI subjects and controls on three simulated driving measures, length of run and mean time to collision (p < 0.001), and number of off-road events (p < 0.01). MCI subjects had only a significantly shorter time-to-collision than healthy controls (p < 0.001). Simple visual reaction times were significantly longer (p < 0.001) in patients with AD, compared to MCI and healthy controls, and showed a borderline significant relation (p = 0.05) with simulated driving scores. Driving performance in the three groups did not significantly correlate with MMSE score as measure of overall cognitive function.

CONCLUSIONS

Mild AD significantly impaired simulated driving fitness, while MCI limitedly affected driving performance. Unsafe driving behaviour in AD patients was not predicted by MMSE scores.

Conversation limits the functional field of view

The purpose of these two experiments is to investigate one possible mechanism that might account for an increase in crash risk with in-car phone use: a reduction in the functional field of view. In two between-subjects experiments, college undergraduates performed a task designed to measure the functional field of view in isolation and while performing a hands-free conversational task. In both experiments, the addition of the conversational task led to large reductions in the functional field of view. Because similar reductions have been shown to increase crash risk, reductions in the functional field of view by conversation may be an important mechanism involved in increased risk for crashes with in-car phone use. Actual or potential applications of this research include improving driver performance.

The Influence of Age and Gender on the Driving Patterns of Older Adults

The purpose of this study was to investigate the influences of age and gender on the driving patterns of 300 older adults. Odds of driving less than every day increased significantly with age and female gender. However, no differences were found in the reduction of overall driving. Females were more likely than men to have stopped or reduced driving under certain adverse conditions and for elective purposes. The driving patterns of today's cohort of older females suggest that the gender gap may be narrowing. Social and cultural issues such as security, safety, and identity with driving may explain existing gender differences.

Assessing the driving performance of older adult drivers: on-road versus simulated driving

To validate a laboratory-based driving simulator in measuring on-road driving performance, 129 older adult drivers were assessed with both the simulator and an on-road test. The driving performance of the participants was gauged by appropriate and reliable age-specific assessment criteria, which were found to be negatively correlated with age. Using principal component analysis, two performance indices were developed from the criteria to represent the overall performance in simulated driving and the on-road assessment. There was significant positive association between the two indices, with the simulated driving performance index explaining over two-thirds of the variability of the on-road driving performance index, after adjustment for age and gender of the drivers. The results supported the validity of the driving simulator and it is a safer and more economical method than the on-road testing to assess the driving performance of older adult drivers.

Aging, driving and vision

Older people constitute the fastest growing sector of the driving population and are believed to represent a high risk to road safety, given their high crash rate per distance travelled. The crash characteristics of the elderly also differ from those of younger drivers and generally involve multiple vehicles and more complex driving situations. Although the reasons for this deterioration in driving performance are multi-factorial, the age-related changes in vision are likely to be a significant factor, given the important role of vision in driving. This paper provides an overview of some of the complex issues associated with older drivers and considers how the aging changes in visual function might impact on driving performance. Particular emphasis is placed on the literature linking vision to driving, with emphasis on more recent research. The implications of this research for driver licensing and self-regulation of older drivers are also discussed.

Age and visual impairment decrease driving performance as measured on a closed-road circuit

In this study the effects of visual impairment and age on driving were investigated and related to visual function. Participants were 139 licensed drivers (young, middle-aged, and older participants with normal vision, and older participants with ocular disease). Driving performance was assessed during the daytime on a closed-road driving circuit. Visual performance was assessed using a vision testing battery. Age and visual impairment had a significant detrimental effect on recognition tasks (detection and recognition of signs and hazards), time to complete driving tasks (overall course time, reversing, and maneuvering), maneuvering ability, divided attention, and an overall driving performance index. All vision measures were significantly affected by group membership. A combination of motion sensitivity, useful field of view (UFOV), Pelli-Robson letter contrast sensitivity, and dynamic acuity could predict 50% of the variance in overall driving scores. These results indicate that older drivers with either normal vision or visual impairment had poorer driving performance compared with younger or middle-aged drivers with normal vision. The inclusion of tests such as motion sensitivity and the UFOV significantly improve the predictive power of vision tests for driving performance. Although such measures may not be practical for widespread screening, their application in selected cases should be considered.

Impaired vision and other factors associated with driving cessation in the elderly: the Blue Mountains Eye Study

The aim of present study was to review vision and other factors associated with the cessation of driving. As part of the Blue Mountains Eye Study, detailed demographic information, driving status and medical history were taken. Visual acuity was measured during a standardized refraction and visual fields documented. Potential risk factors were decided a priori. Among the 3654 Eye Study participants, 2831 (77.5%) had driven a motor vehicle in the past, of whom 2379 (84.0%) were current drivers and 452 (16.0%, 95% CI 14.6-17.4%) said they had stopped driving. Older persons and women were more likely to have stopped driving. After adjusting for age and sex, sensory impairment affecting vision and hearing, plus chronic medical conditions and benzodiazepine use were significantly associated with cessation of driving. The study found that sensory impairment, particularly visual parameters, was associated with the decision to stop driving by older subjects.

Driving and dementia: a review of the literature

In North American society driving is closely linked with independence. Unfortunately, the freedom to operate a motor vehicle may be lost when an individual develops a specific medical diagnosis. The complex issue of dementia and driving safety is frequently encountered by health care professionals. Physicians are required, by law, to report any medical diagnosis such as dementia, that may affect driving safety. Physicians often refer to occupational therapists to assist them in determining if an individual's impairment significantly impacts driving safety. Unfortunately many health care professionals are not using reliable, valid and sensitive tests to determine the point at which an individual with dementia will become an unsafe driver. Through a review of the literature, the authors explore the effects of normal aging and cognitive impairment on driving safety. Specific assessment tools used to assess driving ability are examined and the role of health professionals in driver assessment is discussed. Some suggestions to improve the overall approach to evaluating driving safety are offered in the conclusion.

Comparison of driving performance of young and old drivers (with and without visual impairment) measured during in-traffic conditions

PURPOSE

The aim of this study was to determine whether visual impairment and age affected driver performance and safety rated during in-traffic driving conditions.

METHODS

Participants included 30 younger, 25 middle-aged, and 35 older subjects with normal vision and 47 older subjects with visual impairment. All subjects were legally eligible to drive. Driving performance was assessed during in-traffic conditions by a professional driving instructor and an occupational therapist using specific scoring criteria.

RESULTS

Group allocation significantly affected driving performance as assessed by the driving instructor and occupational therapist (p < 0.05). The driving instructor and occupational therapist scores were highly correlated (r = 0.76). Of the drivers who were scored as being unsafe, all were older and the majority (75%) had visual impairment.

DISCUSSION

Older drivers with or without visual impairment were rated as being less safe than the younger and middle-aged drivers with normal vision.

Autofahren im Alter - eine Literaturanalyse

Zusammenfassung: Seit einigen Jahren beschäftigt man sich verstärkt mit alten Menschen nicht nur als als Verkehrsteilnehmer allgemein, sondern besonders als Autofahrer. Daß zukünftig erheblich mehr alte Menschen mit einem Auto unterwegs sein werden als bisher, hat zu kontroversen Beurteilungen insbesondere der zukünftigen Verkehrssicherheitslage geführt. Die vorliegende Literaturanalyse soll angesichts der Kontroverse klären, was Fakt ist. Gesichtet wurden schwerpunktmäßig Beiträge, die in den 90er Jahren erschienen sind. Eingeteilt wurden sie in jene, die die Leistungsfähigkeit des alternden Organismus im Kontext der Straßenverkehrsteilnahme untersuchen, und jene, die das Problem der Persönlichkeit des alternden Autofahrers thematisieren, wobei die zweite Gruppe deutlich weniger stark besetzt ist. Das Teilthema Leistungsfähigkeit wird von der medizinisch-biologischen zur eher psychologischen Seite hin entwickelt. Dabei wird eine Vielzahl von alterstypischen Veränderungen aufgezeigt, die in der Literatur als mögliche Einflußgrößen für die Sicherheit beim Autofahren diskutiert werden. Die tatsächliche Verkehrssicherheit älterer Autofahrer wird durch eine Analyse der aktuellen Unfallstatistiken untersucht. Dabei zeigt sich, daß Defizite und Leistungsverluste durch günstige Einstellungen und richtige Entscheidungen zumindest teilweise kompensiert werden können, so daß die Unfallstatistiken ein eher günstiges Bild zeigen. Selbstverständlich kann auch die sich fortentwickelnde Technik genutzt werden, älteren Menschen die Bedienung eines Fahrzeuges und die Bewältigung der Fahraufgaben zu erleichtern. Verschiedene technische Möglichkeiten werden vorgestellt.

Very old drivers: findings from a population cohort of people aged 84 and over

BACKGROUND

Increases in longevity will involve a significant increase among the number of drivers in the very old, who are at greater risk of being involved in road accidents. Data are thus needed from studies of older populations to characterize those still driving, the reasons for giving up and to help formulate appropriate policies for dealing with the problems faced and created by an increase in older drivers.

METHODS

A driving questionnaire was administered to surviving members of a cohort comprising a representative sample of individuals aged >/=84, the Cambridge City over 75 Cohort. Out of 546 survivors 404 completed the driving questionnaire at the 9-year follow-up. In addition, subjects were assessed, at baseline and at each follow-up, for cognitive performance using the Mini-Mental State Examination (MMSE) and for physical impairment using the Instrumental of Activities in Daily Living (IADL) scale.

RESULTS

Of the sample, 37% had driven in the past, and 8.4% were still driving, the majority regularly. The drivers tended to be younger (mean age 86.6 years), men (71%) and to be married (67.7%). Although physical disability and cognitive impairment are common in this age group, current drivers had few physical limitations on their daily activities and were not impaired on MMSE. None of the current drivers had visual impairment and 22.6% had hearing loss. Of those who had given up driving, 48.5% had given up at the age of >/=80. The commonest reasons for giving up driving were health problems (28.6%), and loss of confidence (17.9%). One-third reported giving up driving on advice.

CONCLUSION

A process of self-selection takes place among older drivers. People over the age of 84 who are still driving have generally high levels of physical fitness and mental functioning, although some have some sensory loss. Given the likely increase in the number of older drivers over the next decades, safety will be improved most by strategies aimed at the entire driving population with older drivers in mind, rather than relying on costly screening programmes to identify the relatively small numbers of impaired older people who continue to drive.

Characteristics of traffic crashes among young, middle-aged, and older drivers

An overview of the characteristics of traffic crashes among young, middle-aged and older drivers is presented. The results suggest that the youngest and the oldest drivers were more likely to be considered at-fault. With respect to crash characteristics, older drivers were less likely to have crashes involving driver fatigue, during the evening and early morning, on curved roads, during adverse weather, involving a single vehicle, and while traveling at high speeds. Conversely, older drivers were over-represented in crashes at intersections and/or involving failure to yield the right of way, unseen objects, and failure to heed stop signs or signals. Crashes occurring while turning and changing lanes were also more common among older drivers. Alcohol was less likely to be a factor in traffic crashes involving older adults. Synthesizing these results led to the conclusion that the primary problem with the young is risk-taking and lack of skill. The strength of older drivers lies in their aversion to risk, but perceptual problems and difficulty judging and responding to traffic flow often counterbalance this attribute.

Effects of normal aging on the performance of motor-vehicle operational skills

Operational skills involved in controlling a motor vehicle were measured in two groups of very healthy elderly drivers and a young control group to test the hypothesis that there are age-related declines in operational performance that may influence driver safety. An actual behind-the-wheel, standardized road test was employed using a motor vehicle equipped with sensors to record speed, braking activity, and lane position, as well as direction and magnitude of front-wheel and eye-movement excursions. The data from these sensors were used as dependent measures of operational performance. Older drivers made fewer steering and eye-movement excursions and drifted across the center line more frequently than the young control group. Younger drivers drove significantly faster and executed more braking applications than did their older counterparts. The motor-vehicle operational performance of older healthy drivers was related to visual-spatial attentional declines and the useful field of vision associated with the normal aging process.

Driving performance in persons with mild senile dementia of the Alzheimer type

OBJECTIVE

To assess the effect of mild senile dementia of the Alzheimer type (SDAT) on driving ability.

DESIGN

Cross-sectional study with correlation analysis.

SETTING

A university-based Alzheimer's Disease Research Center, which evaluates community-living older adult volunteers, and the university's Program in Occupational Therapy.

PARTICIPANTS

Healthy elderly controls (n = 13) and subjects with very mild (n = 12) and mild (n = 13) SDAT. Dementia severity was staged by the Washington University Clinical Dementia Rating.

MEASUREMENTS

The driving ability of participants on the in-car road test was scored independently by a driving instructor, blinded to the study design and to the dementia status of the subjects, and an unblinded occupational therapist. Interview-based perceptions of driving ability were obtained independently from the subjects and their collateral sources. Attentional and visuospatial performances of the subjects were assessed prior to the road test.

RESULTS

All control and very mild SDAT subjects were judged to be "safe" drivers (ie, passed the in-car road test), but five (40%) of the mild SDAT subjects had driving impairment sufficient to "fail" the road test. Neither subject self-assessment nor caregiver perceptions of driving ability consistently predicted driving performance. Attentional task performance correlated well with road test results.

CONCLUSIONS

Some SDAT subjects retain "safe" driving skills. The greater the dementia severity, the greater the likelihood of poor driving ability. Performance-based (road test) evaluations are necessary to properly determine driving skills at present, but attention and other cognitive screening measures should be developed.