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Introduction

Many people with dementia, particularly men, refuse to give up driving, and families frequently have great difficulty convincing them to stop.^1,2 Also, in my experience, drivers with dementia -- particularly those who live alone -- frequently continue to drive even when they have been advised not to and their driving licences have been cancelled.  

Road safety and dementia

Risks for car accidents are related to speed of information processing and efficient switching of selective attention, both of which are impaired in the early stages of Alzheimer's disease.² When traffic conditions become complex and stressful (e.g., at intersections and roundabouts), demands on drivers with dementia may exceed their driving capabilities.³ Visuospatial orientation is important for selecting the correct side of the road and for making appropriate and safe turns. Impaired judgement would reduce a driver's ability to make appropriate decisions in traffic and to interpret traffic signs. Drivers with dementia would also have difficulty with aspects of driving that rely heavily on recent memory (such as remembering warnings about changed traffic conditions), and may not cope with sudden changes or new environments.

Further, a recent postmortem study of the brains of drivers aged 65 years and older who were killed in car accidents found that over 50% had the neuropathological changes of Alzheimer's disease.⁴

Despite such evidence, and the increased risk of crashes among drivers with Alzheimer's disease (4.7 times that of control subjects),¹ there is still great controversy in the medical literature about the safety of driving for people with the early stages of the disease. Some studies suggest that it would be acceptable to allow a person with early Alzheimer's disease to continue to drive rather that subvert their autonomy and "right" to drive a motor vehicle.^3,5

Medical practitioners in Australia are not obliged by law to report drivers with dementia (there are much more specific guidelines for conditions such as epilepsy or stroke). The current New South Wales Roads and Traffic Authority guidelines for medical practitioners do not specifically exclude all people with dementia from driving (rather, recommending that drivers with dementia should be referred for on-road assessment if their ability to drive is in doubt),⁶ and do not give specific direction about how to assess cognitive function and behaviour in relation to driving skills. The Federal Office of Road Safety does exclude any person with dementia from driving a commercial vehicle.⁷

Restricted licences are commonly issued for impaired drivers in Australia. The use of these licences to allow drivers with dementia to drive only short distances from home has not been proved effective or safe, and may give a false sense of security to drivers with dementia and their doctors based on the erroneous expectation that people with dementia will not have problems if they remain in familiar surroundings. The increased crash risk for drivers with dementia remains even though they may restrict their driving.^2,3 In one study nearly 50% of drivers with dementia incurred at least one crash, compared with only 10% of control subjects, within a five-year period.¹

Having someone act as a "copilot" to assist drivers with dementia has not yet been proved a safe practice and should not be encouraged.⁸  

Identifying impaired drivers

A multidisciplinary team approach involving an occupational therapist and neuropsychologist can help identify unsafe drivers when there is still doubt after a medical assessment.^2,13 The occupational therapist and neuropsychologist are skilled in assessing cognitive impairments such as attentional deficits, impaired concentration, visuospatial impairments, slowed reaction times and distractibility which correlate with impaired driving.

The current criterion standard in assessing driving safety is probably the on-road driving assessment, with specific testing protocols for drivers with cognitive impairments.^9,13 Unfortunately such programs are costly, often geographically difficult to access, can entail lengthy delays and are impractical in view of the enormous number of elderly drivers who require such assessments.  

Identifying dementia

I believe that medical practitioners are failing to detect drivers with dementia because they are not routinely carrying out cognitive screening tests. Together, the short version of the informant questionnaire on cognitive decline in the elderly and the abbreviated mental test are a sensitive tool for detecting dementia.¹⁴ The simple clock drawing test (in which patients are asked to draw the numbers on a round clock face, requiring visuospatial orientation, concentration and planning ability) may also prove to be a very simple and sensitive, but non-specific, screening test for dementia.^15,16 Compulsory screening of all drivers over 70 years old would be the only way to ensure compliance in screening.  

Implications

Driving a car is a privilege and not a right. The evidence is not yet available to support allowing people with dementia to continue to drive. Further, there are no guidelines as to when people with early dementia who have been permitted to continue driving should be reassessed and what sort of end-points should be used in deciding when to terminate their licences.

There are many reasons why a medical practitioner may allow a person with dementia to continue to drive. These include a perceived breach of personal liberty if a licence is cancelled, restriction in lifestyle for the older patient, demands by the older patient to continue to drive, and threats to the doctor-patient relationship.

However, failure to advise a patient with dementia not to drive, failure to document that advice and failure to notify the relevant driver licensing authority may result in injury or death of the patient or of other innocent people. Such failure of patient care and social duty may breach professional ethics and may expose the doctor to legal action.  

Conclusion

To encourage drivers with dementia to surrender their licences, alternative forms of transport need to be arranged, including "community transport schemes" and better public transport.^2,13 Rural drivers with dementia who are forced to give up their licences may be particularly at risk of becoming socially isolated, disadvantaged and perhaps stranded. Still, this is still no excuse for allowing an impaired driver to continue driving.  

References

1. Freidland RP, Kos E, Kumar A, et al. Motor vehicle crashes in dementia of the Alzheimer's type. Ann Neurol 1988; 24: 782-786.
2. Parasuraman R, Nestor PG. Attention and driving skills in ageing and Alzheimer's disease. Human Factors 1991; 33: 539-557.
3. Hunt L, Morris JC, Edwards D, et al. Driving performance in persons with mild senile dementia of the Alzheimer's type. J Am Geriatric Soc 1993; 41: 747-753.
4. Johansson K, Bojdanovic N, Kalimo H, et al. Alzheimer's disease and apolipoprotein E 4 allele in older drivers who died in automobile accidents. Lancet 1997; 349: 1143-1144.
5. Drachman DA, Swearer JM. Driving and Alzheimer's disease: the risk of crashes. Neurology 1993; 43: 2448-2456.
6. Roads and Traffic Authority. Drivers and riders. Guidelines for medical practitioners. 3rd ed. Sydney: NSW Roads and Traffic Authority, 1993.
7. Dementia and other cognitive impairments. In: Medical examination of commercial vehicle drivers. Melbourne: National Road Transport Commission, and Federal Office of Road Safety, 1994.
8. Shua-Haim JR, Gross JS. The "co-pilot" driver syndrome. J Am Geriatric Soc 1996; 44: 815-817.
9. Johansson K, Bronge L, Lundberg C, et al. Can a physician recognise an older driver with increased crash risk potential? J Am Geriatric Soc 1996; 44: 1198-1204.
10. Odenheimer GL, Beaudet M, Jette AM, et al. Performance-based driving evaluation of the elderly driver: safety, reliability and validity. J Gerontol 1994; 49: M153-M159.
11. Fitten LJ, Perryman KM, Wilkinson CJ, et al. Alzheimer and vascular dementias and driving. A prospective road and laboratory study. JAMA 1995; 273: 1360-1365.
12. Kapust LR, Weintraub S. To drive or not to drive: preliminary results from road testing of patients with dementia. J Geriatr Psychiatry Neurol 1992; 5: 210-216.
13. Fox GK, Withaar F, Bashford GM. Dementia and driving: a survey of clinical practice in aged care assessment teams. Aust J Ageing 1996; 15: 111-114.
14. Harwood DMJ, Hope T, Jacoby R. Cognitive impairment in medical inpatients. 1: Screening for dementia -- is history better than mental-state? Age Ageing 1997; 26: 31-35.
15. Watson YI, Arfken CL, Birge SJ. Clock completion: an objective screening test for dementia. J Am Geriatric Soc 1993; 41: 1235-1240.
16. Death J, Douglas A, Kenny RA. Comparison of clock drawing with Mini-Mental State examination as a screening test in elderly acute hospital admissions. Postgrad Med J 1993; 69: 696-700.