Right: Although, at first glance, statistics seem to bear out the claims that elderly drivers are no more prone to road accidents than any other age group, some studies say that these statistics are misleading.
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Arguments in favour of greater restrictions being placed on elderly drivers
1. The relatively low incidence of accidents among elderly drivers is misleading
It has been claimed that although the absolute number of automobile crashes involving older drivers is low, these drivers have a high incidence of crashes per kilometre driven and a higher incidence of crashes involving serious injury or death.
Elderly drivers constitute a relatively small percentage of total road-users. They typically use their vehicles relatively infrequently and tend to drive in familiar areas and under better conditions, avoiding night driving and bad-weather driving. These factors help to account for their apparent safety. However, some studies have indicated that relative to the actual amount of driving elderly motorists do, they represent a major risk to themselves and all road users.
A 1986 United States study showed that 16- to 19-year-old drivers had 28.6 crashes per million miles and 5.6 fatalities per 100 million miles, 45- to 49-year-old drivers had 3.7 crashes and 0.9 fatalities, and drivers aged 85 years and older had 38.8 crashes and 30.7 fatalities. Using data such as this it appears that relative to distance travelled, elderly drivers are the group most likely to be involved in a crash and that the accidents in which they are a part are most likely to result in fatalities.
Another United States study has claimed, 'On the basis of estimated annual travel, the fatality rate for drivers 85 and over is nine times as high as the rate for drivers 25 through 69 years old.'
Statistics for South Australia issued in December 2011 indicate that repeat driving offenders and elderly motorists were most likely to have died or contributed to a death on the state's roads in 2011. Drivers over the age of 60 accounted for 23 of the 102 road fatalities in 2011 - one more than 2010 and the second year in a row for which the age group led the road toll.
After the age of 75, the risk of driver fatality increases sharply, because older drivers are more vulnerable to both crash-related injury and death. Three behavioural factors in particular may contribute to these statistics: poor judgement in making right-hand turns; drifting within the traffic lane; and decreased ability to change behaviour in response to an unexpected or rapidly changing situation.
2. Older drivers are at greater risk of cognitive impairment
Age increases the likelihood of cognitive impairment and cognitive impairment reduces driving competence. In 2009 the number of Australians with dementia was estimated to be 245,000 (over 1.0% of the population). This group is of concern because of the adverse effect the condition has upon driving competence. It has also been noted that in the early stages of the disease neither elderly drivers nor their families may be aware that there is a problem. In 2005 there were nearly 52,000 Australians newly diagnosed with dementia. The group undiagnosed could be just as large or even larger.
An article published in the Lancet in 1997 reported on a postmortem study of the brains of drivers aged 65 years and older who were killed in car accidents which found that over 50% had the neuropathological changes of Alzheimer's disease.
This study has been used to suggest that many drivers over 65 are likely to have some degree of dementia.
The high percentage of these drivers involved in fatal accidents has also been used to support the view that dementia reduces driving capacity.
A 1997 study published in the Medical Journal of Australia noted, '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. When traffic conditions become complex and stressful (e.g., at intersections and roundabouts), demands on drivers with dementia may exceed their driving capabilities. 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.'
It has also been found that some of the medications older drivers take to address conditions such as depression may impair their driving performance. This was suggested in a wide-ranging United States study published in 1992. There were 16,262 persons in the study cohort with 38,701 person-years of follow-up and involvement in 495 crashes resulting in injury. The study suggested a substantial connection between the use of anti-depressives in the elderly and automobile accidents.
3. Elderly drivers are more likely to have a range of physical impairments that reduce their competence
Several studies have found associations between visual acuity, visual field loss, or visual attention and motor vehicle crashes. Medical conditions that have been linked to driving ability or crashes include cardiac disease, diabetes, seizure disorders, Parkinson disease, and stroke.
It has also been demonstrated that lower extremity dysfunction, that is, conditions such as arthritis, which may affect the driver's ability to use the brake and the accelerator may also be implicated in an increased likelihood of car accidents.
Visual attention has been found to be a more reliable predictor of crash occurrence than other measures of visual function. That is, the driver's capacity for sustained visual attention has been suggested as a major determiner of their risk of being involved in a motor vehicle accident. Older drivers typically have a reduced capacity for visual attention.
Although none of these physiological conditions is found exclusively among the elderly, they are most commonly so. It is also the case that many of these conditions can be found in combination in some elderly drivers, dramatically reducing their driving competence.
4. There are no adequate measures in place to monitor the competence of elderly drivers
There are no generally recognised tests for measuring the extent to which driving capacity may have been reduced. It has also been noted that even when an elderly person is known to have a cognitive impairment that would reduce their driving competence there is no automatic requirement that they surrender their licence.
A report published in the Medical Journal of Australia in 1997 noted, '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), 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.'
Routine medical examinations often fail to identify elderly drivers with poor driving habits or those at higher crash risk. Increased crash risk may be associated with a lower score on standard mental competence tests; however, this is not always the case. Also, a spouse or other family member cannot be relied upon to predict the safety of continued driving.
It has been found that persons with borderline cognitive impairment were more likely to be involved in motor vehicle accidents than were those with higher or lower scores. This seems to indicate that in the early stages of a cognitive impairment, the sufferer and his or her family is less likely to recognise the condition and limit the affected person's driving.
It has been suggested that a multidisciplinary approach involving an occupational therapist and neuropsychologist can help identify unsafe drivers when there is still doubt after a medical assessment. 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 are likely to result in impaired driving. It has been suggested that compulsory testing for all drivers over 70 would be the only way of ensuring compliance in screening.
A 1997 study published in the Medical Journal of Australia recommended, 'Doctors should use a recognised form of cognitive screening to assess all their patients over 70 years who drive. Doctors also need better training in medical driving assessments and diagnosis of early Alzheimer's disease.
A number of expert studies have suggested that more funding is needed for on-road assessment of cognitively impaired drivers and that there needs to be more research into the reliability of medical driver assessments, crash risks and cognitive screening measures, particularly for the very early stages of Alzheimer's disease. Future research may also involve interactive computer-based simulations to evaluate on-road driving skills.'
5. The restrictions placed on elderly impaired drivers are inadequate
It has been claimed that the restrictions placed on elderly drivers known to be impaired are not adequate.
Restricted licences are commonly issued for known impaired drivers in Australia. However, critics claim that 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 false expectation that people with dementia will not have problems if they remain in familiar surroundings.
Some authorities have claimed that the increased crash risk for drivers with dementia remains even though they may restrict their driving. 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.
It has been claimed that this situation will not simply resolve itself because currently 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.