Practical Experience-Based Approaches to Assessing Fitness to Drive in Dementia

Frank J. Molnar, MSc, MDCM, FRCPC; Anna M. Byszewski, MD, FRCPC; Mark Rapoport, MD, FRCPC; William B. Dalziel, MD, FRCPC


Geriatrics and Aging. 2009;12(2):83-92. 

In This Article

Assessment of Fitness to Drive in Dementia

When caring for persons with dementia, it is necessary to ask if they drive. A lack of knowledge of patients' driving status does not legally protect physicians should these patients become involved in at-fault motor vehicle crashes. To the contrary, a precedent has been set as physicians have been successfully sued when their patients were involved in crashes due to neurological conditions, even when the physicians were unaware that the patients were active drivers.[23,24]

Moderate-to-Severe Dementia

When cognitive impairment is so severe or obvious that it is clearly unsafe for the patient to continue driving, in-depth testing is not needed.

Mild-to-Moderate Dementia

The diagnosis of dementia does not, however, automatically mean that a person cannot drive. Some people with mild dementia may still be able to drive safely for a limited period of time, but require individualized assessment and periodic follow-up.[3,6] Attempts to mandate that all persons with dementia should be forced to cease driving regardless of whether they are still safe or not, aside from being legally unsupportable, could inadvertently increase the risk to the general public. Such draconian measures could result in more people with dementia avoiding a diagnostic assessment which might thereby result in more people with undiagnosed dementia continuing to drive (i.e., patients whose unfitness to drive might have been detected during the diagnostic assessment).

For less severe cases, clinicians need to decide if they have enough information to make a clinical decision regarding fitness to drive. The Canadian Medical Association driving guidelines[3] and the Canadian Consensus Conference on Dementia guidelines[25] indicate that persons with moderate to severe dementia should not drive, and they employ an opinion-based definition of moderate to severe dementia as demonstrating new impairments (relative to the patient's baseline) due to cognition in one or more personal activities of daily living and/or two or more instrumental activities of daily living (see Table 1 ).

The assessment of fitness to drive in persons with mild dementia is complex and should take into account not only cognitive issues but also other medical and physical reasons indicating that they are unfit to drive. Driving cessation is often more acceptable or palatable to such patients if the decision is also based on physical (i.e., noncognitive) findings. We propose two different methods to organize the complex array of factors impacting on driving (see Table 2 and Table 3 ). The approaches are not as lengthy to apply as they may first appear. Primary care physicians with an in-depth longitudinal knowledge of a patient will be able to answer many of the questions listed in these approaches before meeting with the patient for a more focused examination of fitness to drive. The initial elements of such a focused examination, for example, points 1-5 in Table 3 , may answer the question of fitness to drive; in this case, further assessment (e.g., points 6-10, Table 3 ) may not be necessary. In many instances, the approach suggested in Table 3 may only take 10 minutes to complete.

These approaches are heavily based on history and physical examination. Many clinicians may prefer to start with cognitive tests. When physicians employ cognitive tests such as the MMSE, clock-drawing test and/or Trails A and B, they should keep in mind that none of these tests have well-validated cut-off scores for persons with dementia (and when validated, such cut-off scores will likely be averages and may vary by individual). It is, therefore, recommended that clinicians use their judgment to trichotomize the results of these tests into categories of "clearly safe," "unclear--needs more testing," or "clearly unsafe" by asking themselves if they would get into or allow a loved one in a car that the patient is driving, given the tests results.[5] As presented in point 8 of Table 3 (Trails B) and Figures 1 and 2, the unclear category may be further evaluated by considering qualitative dynamic information regarding how the test was performed (e.g., observations such as slowness, hesitation, multiple corrections, anxiety, impulsive or perseverative behaviour, lack of focus, forgetting instructions, inability to understand test, etc., may facilitate more precise judgment of this category). Given the lack of research on validated cut-off scores, and on trichotomization in general, where to set the cut-off scores remains dependent on physician judgement pending further research.[5] The trichotomization approach essentially asks, "Which patients are obviously unfit to drive, which are clearly safe, and which require further evaluation?"

Figure 1.

Serial Trichotomization

Figure 2.

Trichotomization Approach to Interpretation of Cognitive Test Results With Respect to Fitness to Drive

What to Do if Fitness to Drive Remains Unclear

If fitness to drive remains unclear after performing assessments such as those described in Table 2 - Table 3 and Figures 1-2, then physicians should refer for further evaluation. Referral to a centre specializing in the diagnosis and treatment of dementia should be considered if there are dementia-related issues other than driving to also consider (i.e., there are insufficient resources in dementia clinics to handle large numbers of referrals purely for assessment of fitness to drive). If fitness to drive is the only issue to be addressed then referral to a centre providing specialized on-road testing would be more appropriate (in regions where such centres exist).

This recommendation comes with a caveat. In some provinces the ministry of transportation will not accept their own on-road tests as being sufficient to assess persons with cognitive impairment. Rather, the ministry of transportation requires that a more comprehensive on-road evaluation be performed at specialized ministry certified centers that are often run by occupational therapists. The high costs of these specialized comprehensive on-road tests ($500-800 to be paid by the patient in some provinces) create a barrier to the assessment and reporting of fitness to drive as they place physicians in the position of presenting patients with an ultimatum; pay for such expensive on-road tests or stop driving.

This type of interaction is destructive to the physician-patient relationship and is unfair to patients of limited financial means. Systems in which patients have to pay for on-road testing discourage physicians from assessing and reporting fitness to drive and may thereby unintentionally create a risk to public safety. Some provinces such as British Columbia have addressed this by funding comprehensive on-road testing for patients with dementia if the physician recommends such on-road testing to the ministry of transportation and the ministry agrees with this recommendation. In Quebec on-road testing only costs patients $80. Ideally all provincial and territorial ministries of transportation should fund comprehensive on-road testing for persons with dementia in the way British Columbia and Quebec do. Regrettably, most ministries of transportation are not themselves adequately funded by their province to undertake this responsibility. If we, as a society, want to have safer roads then we must ask our provincial governments to better fund our ministries of transportation so they, in turn, can fund comprehensive on-road testing.

Another approach would be to consider which organizations would benefit financially from better funded comprehensive on-road testing. When people are involved in car crashes (as drivers, passengers, pedestrians, or drivers and passengers of other cars), it is the ministries of health and the insurance industry that pay the extremely high immediate and long-term costs of care and disability. The health care system and the insurance industry could potentially save tax payers and investors millions of dollars by funding comprehensive on-road testing or by sharing the costs with the ministries of transportation (i.e., a tripartite payer system including the insurance industry, ministries of health, and ministries of transportation). Such forward thinking could save both lives and money.

After the Assessment: Approaching a Person with Mild Dementia who Is Still Temporarily Safe to Drive

If a person with mild dementia is found to be able to continue to drive safely, physicians should still broach the subject of eventual driving cessation when the dementia progresses (as it inevitably will). Fitness to drive must then be re-evaluated every 6-12 months.[3,29] If the clinician is concerned that the patient may not return for re-evaluation, then it would be prudent to report the patient to the ministry of transportation as "having mild dementia, but being deemed still safe to drive with re-evaluation required in 6-12 months (period for re-evaluation dependent on physician judgment)." The physician also has the option of specifying the type of follow-up required (e.g., in the physician's office, by a specialist, or via comprehensive on-road assessment) when completing this form.


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