Driving and dementia

Crash data

The risk of crashes in patients with dementia has been extensively studied (table⇓). Over the course of the disease evidence suggests that the risk of a crash is significantly increased. As a general rule, however, the risk seems to remain acceptably low for up to three years after the onset of dementia, by which time most patients have stopped driving. A more detailed analysis of data on crash risk in dementia is provided on bmj.com.

Who decides on medical fitness to drive?

Although the Driver and Vehicle Licensing Agency in the United Kingdom has the legal responsibility of deciding on medical fitness to drive, general practitioners and specialists have important parts to play (figure⇓). The Royal College of Psychiatrists13 and the General Medical Council14 have gone to considerable efforts to clarify their expectations of reasonable practice. The council is clear that for several conditions (including dementia), doctors should not only advise patients of the possibility of stopping driving but also take steps to ensure that the relevant statutory authorities are informed of breaches of regulation if there is reasonable concern about public safety. Studies have found that psychiatrists have a poor knowledge of the guidelines issued by the Driver and Vehicle Licensing Agency and that relatively few patients are advised that they should not drive, although the reasons for this pattern of advice may be complex.^{w17 w18}

Clinical pathway for advice on driving after a diagnosis of dementia

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What should I do in the clinic?

Whenever dementia is diagnosed it is vital to inquire about the driving status of the patient and to maximise traffic related health (for example, checking visual acuity, ensuring arthritis does not affect ability, and reviewing medications). The Driver and Vehicle Licensing Agency states that anyone holding a driving licence must, by law, inform the agency when given a diagnosis of any medical condition that might affect safe driving (box 1).15 Providing a patient with a pro forma can help with provision of information to the Driver and Vehicle Licensing Agency. Providing written information and advice (such as the leaflet on driving and dementia produced by the Alzheimer's Society16) is also advisable. Clinicians must make an immediate decision on whether the patient is fit to continue driving while further assessment is arranged. All decisions and actions should be documented in the patient's notes.

It is important to advise patients and their families on an individual basis of the predicted decline in driving ability, although three years from when the disease becomes clinically obvious may be reasonable. This allows patients to plan for when they stop driving and to look for alternative transport options. This in itself is a compelling reason to share the diagnosis of dementia with a patient who drives. Many older people do not, however, consider public transport to be adequate or efficient and often see it as a threat to their security.^w19

Clinicians should ask family and friends about specific incompetent driving behaviours such as driving the wrong way round roundabouts, getting lost in familiar areas, miscalculating speed and distances, and poor judgment. It has been shown that knowledgeable informants can detect dementia reliably and accurately, even in its early stages.^{w20 w21} Family members can help patients realise that it is no longer safe for them to drive, but family may also have ulterior motives for maximising or, more usually, minimising driving difficulties, of which clinicians should be aware.

A doctor has a duty to inform the licensing authority if there is a reasonable likelihood of danger to other road users when patients will not or cannot inform the agency and continue to drive. Doctors should also check that patients are adhering to the guidelines.

How does the Driver and Vehicle Licensing Agency make its decision?

When the Driver and Vehicle Licensing Agency is informed of a diagnosis of dementia a medical adviser requests a report from the relevant doctor. The completion of the report may be aided by input from a specialist in old age psychiatry, geriatrician, or neurologist. For this reason many general practitioners refer patients to specialists in the early stages of disease. Some psychiatrists believe that the forms provided by the Driver and Vehicle Licensing Agency are unsatisfactory.^w23 Difficulties can also arise because completion of the form usually takes place at the time of diagnosis and before the effects of treatment have been established. Depending on the information received, the agency may issue a new licence valid for one year (subject to annual review) or revoke the licence (with the possibility for appeal). A slow response from the agency may mean that patients continue to drive for months before the decision is made.

The agency's medical adviser may request an on-road driving assessment of the patient. This is generally seen as the ideal means for assessing an ageing driver.^w24 The patient is assessed on a predetermined test route in a vehicle with dual controls. Among other things, the patient is graded on sense about road position, response to road signals, and awareness of other road users (Scottish Driving Assessment Centre, personal communication, 2006). Although drivers with dementia tend to perform at significantly lower levels in this type of test,^w25 a significant minority will perform at an acceptable level. The main drawback of on-road testing is the geographical spread of the 17 testing centres in the United Kingdom, although the numbers are increasing (Driver and Vehicle Licensing Agency, 2006).

Patients with dementia must also inform their insurance company of their diagnosis. Failure to disclose this information may invalidate their policy. The Association of British Insurers has advised that, provided the Driver and Vehicle Licensing Agency is satisfied that someone with a diagnosis of dementia is fit to hold a licence, then he or she should be treated no differently from an applicant without a disability or disease (Association of British Insurers, personal communication, 2006). This situation may change with the accumulation of actuarial data.

What is the role of cognitive function testing?

Clinicians can carry out a variety of clinical, cognitive, behavioural, and activities of daily living tests to accurately complete the Driver and Vehicle Licensing Agency report, and these tests are well described in the literature.17 18 Although statistically significant differences in cognitive function testing have been shown between dementia groups and controls, overlap between group scores make these tests unusable. This reflects in part the differences in the cognitive deficits between dementia subtypes, a failure to observe and examine these separately in research studies, and great variability in the presentation and course of the dementias. Indeed it is reasonable to say that few, if any, of the tests have any congruence with modern thinking on models of driving behaviour.^{w28 w29} For these reasons the British Psychological Society has stated that “no one test, or sets of tests, can as yet be recommended for off-road assessment.”19 A recent systematic review of cognitive tests that might be used in clinical settings found that no tests (not even clock drawing or trails B tests recommended by the American Medical Association20) are robust enough to be used in clinical practice other than to assist in determining the need for further evaluation of driving.18 Even the mini-mental state examination is of little value in drawing fine distinctions between patients with early Alzheimer's disease for capacity to drive safely.5

Relicensing for drivers with dementia in the European Union and North America

The European Council directive 91/439/EEC sets out the minimum standards of physical and mental fitness to drive at any age. It makes no specific reference to dementia and so interpretation varies significantly between member states. The subject of relicensing was comprehensively investigated in 2000, with all 15 contemporary EU members surveyed.21 The United Kingdom was the only EU country in which patients had an obligation to inform their driving authority when an illness was diagnosed that may affect driving ability. A system that relies heavily on self reporting can face difficulties in conditions such as dementia where patients are unaware of their compromised driving ability.

State governments in the United States have a variety of methods for increasing the stringency of the licensing process for older people, including the adoption of in-person renewal requirements, vision tests, road tests, and a shorter renewal period.^{w36 w37} In Canada most states have mandatory reporting requirements.^w22

Conclusions

Some patients with early dementia are capable of driving safely. The three year rule, which broadly states that with regular review the risk of crashes in patients with Alzheimer's disease is acceptably low for up to three years after the disease becomes clinically apparent, has been proposed as a means of guiding relicensing policy. Whatever the relicensing rules, doctors in the United Kingdom must ensure that the Driver and Vehicle Licensing Agency is informed of all new diagnoses of dementia. They must also adequately complete a medical report, on which the licensing agency will base its decision on fitness to drive. The challenge for doctors and the licensing agency is to balance mobility and safety in the growing proportion of older people in the population. To this end the UK Department of Transport is to launch a public consultation to consider changes to relicensing. Current evidence from Scandinavia, Australia, and the United States, however, suggests that mass medical screening or cognitive screening of older drivers has negative consequences for public health.22 23 24 Therefore the main thrust of future measures should focus on opportunistic screening of high risk populations, such as those attending memory clinics, and the refinement of effective pathways for clinicians and the Driver and Vehicle Licensing Agency to manage mobility and safety,^w35 a position recently adopted by the House of Lords Science and Technology Committee.^w38