Driving and dementia: balancing personal independence and public safety

Drivers with dementia require standardised on-road assessment of their driving safety

MJA 1997; 167: 406-407

In this issue of the Journal, Lipski addresses the important topic of driving by people with dementia.

Although older drivers drive fewer kilometres than younger drivers, and are less likely to drive at night or in heavy traffic, their crash rate per kilometre driven may be the highest of any age group, and they are more likely to be killed when involved in a crash.

Several retrospective studies have found that people with dementia are involved in more accidents than age-matched control subjects, and that many drivers with dementia continue to drive despite having had crashes. Notably, these studies do not agree on issues such as whether the duration of the dementia is an accurate predictor of driving ability, and many rely on reports by caregivers of driving history and crashes, the reliability of which are uncertain.

Recent neuropathological findings in 98 older drivers killed in traffic accidents showed that 33% had neuritic plaque scores indicating certain Alzheimer’s disease (AD) and, in a further 20%, findings were suggestive of AD. This raises the possibility that more accidents are attributable to AD than previously thought. In contrast, another study of Michigan State records showed that road crash and violation rates among AD patients did not differ significantly from those of matched controls; this study did not control for mileage driven, and reduced driving exposure of AD patients may have kept their crash rate equal to that of control subjects. Drachman and Swearer investigated crash rates for patients with AD over a 10-year period. They also did not control for mileage driven, but found that, although the AD patients had fewer reported crashes than 16-24 year old drivers, they had more than twice as many in the years after the onset of their AD, than matched control subjects.

“Doctors cannot reliably predict driving competence or increased crash risk in drivers with AD on the basis of a clinical examination”

There are few reports on actual driving performance of people with dementia. Fitten and colleagues examined the performance of patients with mild AD and patients with mild vascular dementia. Compared with control groups, the groups with AD and vascular dementia had lower mean scores on the driving test and made more errors in the complex stages of the course. In addition, a retrospective analysis of crashes and driving violations for these patients was consistent with road test results. However, Hunt and colleagues found that, while 40% of drivers with mild dementia of the Alzheimer type (DAT) were unsafe, some others may drive safely. The driving competency of individuals with DAT could not be determined reliably from self report. Fox and colleagues found that 63% of licensed drivers diagnosed with probable AD failed a standardised on-road evaluation.11 Conversely, 37% passed this evaluation, suggesting that a diagnosis of AD alone may be insufficient justification for stopping people from driving. These studies of on-road driving behaviour of patients with dementia indicate that older drivers with a range of cognitive abilities can be safely and reliably evaluated by a road test, with validity equal to that of driver licence tests.

As noted by Lipski, while data increasingly show risks to individuals and the community associated with driving by people with dementia, there are few guidelines for helping doctors determine who can or cannot drive. This assessment may be further complicated if any of the new drugs currently undergoing clinical trial for AD are found to enhance performance on cognitive or driving tasks. Doctors cannot reliably predict driving competence or increased crash risk in drivers with AD on the basis of a clinical examination.10 There is also a lack of consensus about the predictive validity of neuropsychological assessment for driving competence among patients with dementia, partly because of the different neuropsychological tests employed in different studies. While the Mini Mental State Examination has been proved to significantly predict driving competence in studies of patients with dementia, its specificity and sensitivity were not sufficient for efficient prediction of driving safety.

In the light of recent empirical data, we recommend that if a doctor learns that an older patient gets lost while driving or has been involved in a crash, the possibility of a progressive dementing illness as a cause of their driving difficulties should be investigated (This includes OT Driving Assessment).

In many cases, licence cancellation may be indicated without on-road assessment. If licence cancellation threatens a general practitioner’s long term relationship with a patient and his or her family, referral to an appropriate specialist may be preferable. In cases of disagreement, an on-road driving test may help the family, and possibly the patient, accept that the patient is incompetent to drive.

In patients for whom unsafe driving behaviours have not been reported, an on-road OT assessment is currently the most valid means of determining driver competence and safety. The driving test should be standardised, designed for neurologically impaired people, include some complex traffic situations, and, ideally, should be available in both urban and rural areas. It has been suggested that patients with dementia who drive with the assistance of a passenger or “copilot” should be assessed with, and subsequently permitted to drive with, the “copilot”.  However, several logistic and legal problems (surrounding such questions as: Who is licensed to drive? How can the presence of the “copilot” be ensured? Can the cognitive status of the “copilot” be monitored?) render this proposal impractical.

For patients whose driving tests indicate safe and competent driving, driving performance must be reviewed regularly (e.g., six-monthly), or after a noticeable increase in dementia severity. Criteria for driving competence and licence cancellation should be discussed with the patient and family. If assessment indicates that the patient should stop driving, the patient and family should be involved in discussion of transport alternatives which may be available from family or friends, or through community transport options. Counselling of the patient and family about lifestyle changes and future planning of transportation may be critical to compliance as well as to psychological wellbeing, as driving cessation may be associated with depressive symptoms.

As a society, we need to devote more planning and resources to provision of safe, convenient and affordable transportation alternatives for those unable to drive.

Authors:

Gillian K Fox: Clinical Neuropsychologist, Rehabilitation Studies Unit, University of Sydney, NSW.

Guy M Bashford: Staff Specialist, Department of Rehabilitation and Geriatrics, Illawarra Area Health Service, Warrawong, NSW

This article sourced from an article published on the Internet by The Medical Journal of Australia http://www.mja.com.au/public/issues/oct20/fox/fox.html

References:

1.          Lipski PS. Driving and dementia: a cause for concern. Med J Aust 1997; 167: 453-454.

2.          Waller PF. Renewal licensing of older drivers. Transportation in an aging society. Vol. 2. Washington, D.C.: Transportation Research Board, 1988: 72-100.

3.          Friedland RP, Koss E, Kumar A, et al. Motor vehicle crashes in dementia of the Alzheimer type. Ann Neurol 1988; 24: 782-786.

4.          Lucas-Blaustein MJ, Filipp L, Dungan C, Tune L. Driving in patients with dementia. J Am Geriatr Soc 1988; 36: 1087-1091.

5.          Gilley DW, Wilson RS, Bennett DA, et al. Cessation of driving and unsafe motor vehicle operation by dementia patients. Arch Intern Med 1991; 151: 941-946.

6.          Johansson K, Bogdanovic H, Kalimo H, et al. Alzheimer’s disease and apolipo- protein E e 4 allele in older drivers who died in automobile accidents. Lancet 1997; 349: 1143-1144.

7.          Trobe JD, Waller PF, Cook-Flanagan CA, et al. Crashes and violations among drivers with Alzheimer disease. Arch Neurol 1996; 53: 411-416.

8.          Drachman DA, Swearer JM. Driving and Alzheimer’s disease: the risk of crashes. Neurology 1993; 43: 2448-2456.

9.          Fitten LJ, Perryman KM, Wilkinson CJ, et al. Alzheimer and vascular dementias and driving. JAMA 1995; 272: 1360-1365.

10.        Hunt L, Morris JC, Edwards D, Wilson BS. Driving performance in persons with mild senile dementia of the Alzheimer type. J Am Geriatr Soc 1993; 41: 747-53.

11.        Fox GK, Bowden SC, Bashford GM, Smith DS. Alzheimer’s disease and driving: prediction and assessment of driving performance. J Am Geriatr Soc 1997; 45: 949-953.

12.        Shua-Haim JR, Gross JS. The “co-pilot” driver syndrome. J Am Geriatr Soc 1996; 44: 815-817.

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