Use of Self-Reporting

Studies looking at self-reports of crashes and abnormal driving behaviour have found problems with recall bias. Holland showed that most drivers perceived their own chance of having a road accident to be significantly lower, and their own skill to be greater, than that of their peers.² When this is enhanced by the forgetfulness and lack of insight found in dementia, there are obvious shortcomings with using self-report alone as a method of risk assessment.

Use of Carer Reporting

A commonly used source of information on a patient’s fitness to drive is an interview with carers, but Johnson noted that friends and relatives do not always give a true picture.³ This may be because they do not wish to take away the patient’s independence, or because they do not wish to become burdened by a relative who can no longer drive but wishes to remain sociable. Partners may overestimate driving ability if they rely on their loved one to get around or have memory impairment themselves. Informants are also wary of being blamed for a patient’s licence being taken away.

Adler et al. found drivers with dementia had a greater risk than controls of crashes and getting lost, and relatives often took over responsibility for the transportation needs of older family members.⁴ They also found that concerned relatives tried to stop individuals with dementia from driving, but long-standing family dynamics often interfered with the sensitive negotiation required. Older people are more likely to accept a recommendation to stop driving from a doctor or authority figure than from a relative or friend.

A study by Brown et al. suggested that both patient and informant perception of driving ability did not relate well to actual driving ability.⁵ Participants (with mild, very mild or no dementia), informants and an experienced neurologist were asked to rate participants’ driving ability as safe, marginal or unsafe. The participants then underwent an on-road driving assessment with a professional driving instructor. Only the neurologist’s ratings correlated with the on-road driving assessment.

However, Croston et al. reported that informants often observed drivers with Alzheimer’s dementia (AD) having difficulty with traffic awareness, maintaining appropriate speeds and staying in their own lane.⁶ This suggests informants may be reliable sources of information if asked appropriate and relevant questions about driving safety.

Use of Other Collateral Information

It may be useful to enquire whether the patient has been involved in any recent accidents, or indeed a community psychiatric nurse may report seeing dents and scratches appearing on the car. Collecting data from police records and insurance companies poses difficulties as diagnoses of dementia may be unknown, especially in the early stages, and minor bumps and offences often go unnoticed or unreported.

Two studies from the United States have looked at state-recorded crash details and found that the crash and violation rates of individuals with dementia were not significantly different to those of age-matched controls.^{7, 8} Both studies found, however, that patients with dementia did not drive as frequently or as far as controls and the crash characteristics between the two groups differed, with the dementia group having more at-fault crashes.

The Importance of the Clinical Presentation

It is really important to consider the nature of the symptom profile and natural history of the patient’s specific dementia. Establishing the dementia subtype is important, as some subtypes are associated with higher risk than others. DLB (dementia with Lewy bodies) and FTD (frontotemporal dementia) are the riskiest dementias in relation to driving.⁹ The hallucinations associated with DLB are likely to have an impact on attention when driving, and any parkinsonian symptoms will affect reaction times.¹⁰ The changes in impulsivity, forward planning and shifting attention found in FTD mean driving skills can be affected very early in the disease.

Studies looking at specific types of dementia have mostly focused on people with AD. Most individuals with moderate to severe AD are unsafe or unable to drive, so studies have focused on the mild to very mild end of the spectrum, ^{5, 11} with very mild dementia being equivalent to MCI.

Drivers with a mild dementia were found to have an increased risk of crashes and abnormal driving behaviours and a faster rate of decline than those with very mild dementia.¹¹ It has been suggested, therefore, that those individuals with mild AD have their driving status reviewed every six months, while those with MCI should be reviewed every year.

The general consensus is that it is usually safe to continue driving for around 3 years after the onset of AD.^{7, 12, 13} Other dementias, such as the vascular type, may remain stable for longer, although the cognitive decline is far more unpredictable. As discussed earlier, FTD and DLB usually require individuals to stop driving much earlier. Sleep disturbance, anxiety and low mood associated with dementia may also affect driving ability by reducing concentration.¹⁴

Consider Comorbidities

Older people with dementia often have multiple physical comorbidities that can affect driving ability and may require the individual to stop driving. Medications prescribed for physical comorbidities, as well as antidepressants and antipsychotics, can affect sensorimotor and perceptual abilities that might have a further detrimental effect on driving ability.

Modification of Driving Behaviour

It is important to appreciate that many older people begin to modify their driving behaviour with time, avoiding busy roads at busy times, using familiar routes and not driving in bad weather or at night. When comparing driving safety statistics and age, this needs to be taken into account. Previous perceived wisdom that older people as a group have more crashes has been disproven, as studies have established this is on account of low mileage and not increasing age.¹⁵ Evidence suggests that patients with AD usually modify their driving behaviour, but this is often not enough to reduce their crash risk completely.^{4, 16}

Impact of Available Alternative Transport

Around the world there are clear differences in vehicle use between rural and urban areas. Across all age groups, people are less likely to drive in cities than in the country, because of readily available public transport systems and overcrowded roads. In rural areas, a car can be a lifeline for individuals where alternative transport is non-existent and travel is required to access food and other services.³

Declining mobility and physical disability associated with ageing has been shown to lead to a reliance on private vehicles, as other forms of transport such as walking and public transport are no longer realistic options.¹⁷ There is also evidence that older people do not feel public transport is adequate, efficient or safe enough for their needs.¹³

Driving Cessation

A number of studies have looked at driving retirement and found that very few people even consider making plans for when they are no longer able to drive.^{4, 6} This is an inevitable stage of life for most people, Foley et al. showed that men tend to outlive their driving ability by 6 years and women by 10 years.¹⁸ Even when given a diagnosis of dementia, many individuals do not make plans for complete driving cessation.^{3, 13} This may in part be caused by individuals not recognizing they have impairment as a result of their cognitive state, which is quite different to people with physical illnesses such as epilepsy or visual problems when insight is not impaired.

Making the decision to retire from driving will have significant psychosocial consequences that may have a negative impact on people with dementia. Marottoli et al. have shown that cessation of driving leads to a significant reduction in out-of-home activity levels, as well as an increase in depressive symptoms.^{17, 19} It is increasingly clear that to stop driving is a life-altering decision, reducing independence and limiting access to family, friends and services.¹³

DVLA and the Law

In the UK, driving licences are provided by the DVLA. Since the agency was set up in 1972, it has developed medical guidance for many illnesses that can adversely affect driving ability. Dementia has only been recognized as a specific condition in recent years. Prior to this, dementia and cognitive impairment were grouped under ‘neurological conditions’. Over time, guidelines for many medical conditions have become clearer and tighter; however, the current guidance for drivers with dementia remains necessarily nebulous (see Box 10.1).²¹

Box 10.1 DVLA guidance

(This applies to Group 1 – car and motorcycle licences. Dementia precludes drivers from holding a Group 2 – bus and lorry licence – and such licences should be surrendered or will be revoked when a diagnosis is made.)

‘It is difficult to assess driving ability in people with dementia. The DVLA acknowledges that there are varied presentations and rates of progression, and the decision on licensing is usually based on medical reports.

Considerations include:

• 
  

  poor short-term memory, disorientation, and lack of insight and judgement almost certainly mean no fitness to drive

  
  
• 
  

  disorders of attention cause impairment

  
  
• 
  

  in early dementia, when sufficient skills are retained and progression is slow, a licence may be issued subject to annual review.

A formal driving assessment may be necessary’

Driver and Vehicle Licensing Agency. Assessing Fitness to Drive: A Guide for Medical Professionals. DVLA, 2019.

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Related posts:

Chapter 3 – Young-Onset Dementias Chapter 7 – Drug Misuse in Older People Chapter 13 – To Scan or Not to Scan Chapter 15 – What Can Person-Centred Care in Dementia Learn from the Recovery Movement? Chapter 22 – Deprivation of Liberty Chapter 19 – Reducing the Healthcare Burden of Delirium

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