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Progressive dementia (most often Alzheimer’s disease) is a major concern in an aging population. The most common deficits seen in dementia are impairments in memory, concentration (vigilance), judgement, and eventually, motor function. The impact of these and other cooccurring losses on everyday activities is devastating. One activity of particular importance is driving. In our society, driving has a special status among activities as it is considered a necessity, a right, and a symbol of independence (1–3). However, this “right” must be balanced by the need for public safety. While driving is a common activity across all age groups and is not without risk, there are age-related changes owing to dementia that create specific risks. Other studies have examined the deficits among drivers with dementia. This paper determines a quantitative estimate of the size of the problem that we are currently experiencing and are likely to experience in the next 25 years in Ontario. To our knowledge, this has not yet been done. Developing this estimate is a considerable challenge that involves addressing the dynamic nature of dementia while logically combining such unrelated data sets as Ontario census data, Canadian dementia prevalence data, Ontario driver licensing statistics, motor vehicle crash data in cognitively impaired older adults, and morbidity data for persons diagnosed with dementia. Many studies have demonstrated shifts in our population demographics that show people are surviving into their senior years and seniors are living longer (4–7). Age is known to be a major risk factor for the development of dementia, and as individuals age, their probability of developing dementia increases sharply (8). It is also known that the proportion of seniors who drive is increasing (Table 1; 9). The consequence of these demographic trends is that there will be a greatly increased number of potentially dangerous drivers. Available data show that the problem is significant now and will grow substantially in coming years. Using census data (10), driver licensing data (9), and dementia projections (11), this paper calculates the size of the problem of driving and dementia in Ontario over the next 25 years.
Though popular media increasingly present reports related to driving and the elderly, the problems of normal aging (for example, reductions in vision and dexterity) are often confused with the problems of pathology in general and dementia in particular. Although normal aging and various medical conditions can each result in legitimate and significant problems for drivers, these are separate issues. This paper refers only to the increasing problems created by the high prevalence of dementia among the population aged 65 years and over. Size of the ProblemSeveral factors must be considered when estimating the number of drivers in Ontario with dementia, including the population and driving rate of persons aged 65 years and over, dementia prevalence rates, and the effects of the progression of dementia. The number of persons aged 65 years and over has grown substantially in recent years and is projected to continue growing in the next 25 years. Some of the earliest dementia projections emerged following the 1986 census (12). Regarding population data, persons aged 65 years and over increased from just under 1 million in 1986 to over 1.5 million in 2000 and are projected to increase to nearly 3.25 million in 2028 (10). This would represent an increase of more than 225% since 1986 (Table 1). In 1994, nearly 60% of persons aged 65 years and over had a driver’s license (Table 1; 9). In 1999, this increased to 67%, probably reflecting generational aspects of driving. Until the 1960s, most drivers were men and most had above-average income levels (13,14), but since then, driving has become almost universal. The current driving rates for persons aged between 20 and 50 years is just over 90%. Allowing for some attrition in this rate, we estimated that at least 85% of persons aged over 65 years will hold a driver’s license in 2028. Therefore, the estimated number of drivers aged 65 years and over will have increased from just under 500 000 in 1986 to nearly 2.5 million in 2028 (Table 1). The overall dementia prevalence rate for those aged 65 years and over in 2000 was 8.7% (11). This rate is slowly increasing as a greater proportion of the population lives longer. However, since institutionalization is almost synonymous with the later stages of dementia, and because patients entering long-term care facilities are usually too debilitated to drive, it is estimated that only one-half of all dementia patients present a concern regarding driving. Therefore, the rate of concern for dementia patients is approximately one-half that of the overall rate of dementia, which we refer to as the “community dementia rate” (Table 1). According to this logic, multiplying the 1986 community dementia rate by the population aged 65 years and over for that same year yields an estimated 40 000 dementia patients of concern in Ontario in 1986. In 2000, the estimated number of dementia patients will have risen to nearly 70 000, representing a 70% increase since 1986. Projecting forward to the year 2028, it is estimated that there will be over 150 000 dementia patients of concern potentially driving in Ontario (Table 1; 11). We assessed the number of drivers with dementia by multiplying the number of drivers aged 65 years and over by the average community dementia rate for a given year (see Table 1). For example, to calculate this number for the year 2000, we multiplied the number of drivers for that year (1 026 177) by the corresponding community dementia rate (4.43%), for a total of 45 473 drivers with dementia. In 2028, we multiplied the estimated drivers (2 428 028) by the community dementia rate (4.75%), for a total of 130 709 drivers with dementia. We refer to this value as a maximum number because it assumes the independence of 2 variables, holding a driver’s license and suffering from dementia, which may not be the case. Although these figures represent the total pool of estimated drivers with dementia, one must consider how many of these individuals are actually driving. Studies that examine the interval between the onset of symptoms and driving cessation are informative in this regard. Lucas-Blaustein and colleagues reported that 30% of their sample subjects had at least 1 accident since the onset of dementia symptoms, and an additional 11% were reported to have caused an accident (15). At the time of the study, 30% of the sample subjects continued to drive for 3.6 years following diagnosis. Fox and others reported that their study subjects were driving an average of 4 years (SD 2.0) following diagnosis (16). In a study by Bedard and colleagues, the mean interval between the onset of symptoms and a clinical assessment that included information about patients’ driving history was 5.5 years (95%CI, 5.2 to 5.8 years) (17). Many of these subjects were still driving at the time of the assessment. In a review paper by Carr, the author concludes from the cited literature that only 50% of drivers with dementia of the Alzheimer type stop driving within 3 years of disease onset (18). Generally, the literature shows that individuals with dementia continue to drive for approximately 4 years after the onset of symptoms. Because the average duration of dementia, at least of the Alzheimer’s type, is about 8 to 10 years after the onset of symptoms, it appears that persons with dementia continue driving well into the disease. Individuals typically spend 4 to 5 years in the community before placement, suggesting that perhaps 80% of the estimated maximum number of drivers with dementia are still driving (19–21). Allowing for some additional attrition, we argue that a rate of 75% is more realistic and is what we have termed the best estimate of drivers with dementia (Table 1). This group has increased from nearly 15 000 in 1986 to more than 34 000 in 2000 and is projected to increase to nearly 100 000 by 2028 (Table 1). In Ontario, the population cohort aged 80 years and over is of particular interest to the Ministry of Transportation (the issuer of motor vehicle licenses in the province). This group is currently screened every 2 years. The screening process consists of a road-sign test and a vision test and requires attendance at a 90-minute information session. In the past, a road test was also included. It is unclear why the process has changed, but it may be a result of significant increases of drivers aged 80 years and over and associated costs. Initiating the current screening process only after an individual’s 80th birthday has important implications. First, a significant proportion of potentially dangerous drivers with dementia will be overlooked: those aged under 80 years. As shown in Table 1, there may be over 98 000 drivers with dementia by 2028. Approximately 60 000 (62%) drivers within this total are aged 80 years and over; over 37 000 (38%) drivers with potential dementia are unscreened (Table 2). Second, the screening process itself is not designed to detect drivers with dementia, and persons in the earlier stages of dementia may not be detected in the screening process. Ideally, a screening process would target individuals in the early stages of the disease.
DiscussionThe problem of drivers with dementia has grown significantly, creating a dangerous situation on our increasingly busy roads and highways. Drivers in the earliest stage of dementia may pose relatively little risk, but with disease progression, they will become increasingly dangerous to themselves and others, until they are no longer capable of driving. Crash data studies have demonstrated that drivers with dementia are 2 to 5 times more likely to be involved in a collision, compared with drivers with no dementia (18,22). Further, several studies have shown that individuals with dementia are most likely to be involved in crashes at intersections, (23,24) suggesting that more than one vehicle is involved. Therefore, when one considers the potential number of crash victims, it is clear that this is becoming a major public health issue. Prior to 1996, Ontario’s Ministry of Transportation required that drivers aged 80 years and over undergo an annual relicensing procedure consisting of a vision test, a written test, and a road test (25). When the number of drivers aged 80 years and over was relatively small, this procedure worked reasonably well. Since 1996, the relicensing process has changed: the road test is no longer a standard component, and the Ministry mandates participation in a 90-minute information session. License renewal now occurs every 2 years. While the vision and road-sign tests have obvious value in assessing basic driving abilities, they do not address drivers with dementia. It remains unclear what the 90-minute information session accomplishes. The need for assessing older drivers is greater now than ever. While the old systems of manual screening with road tests may have detected the more obvious instances of drivers with dementia, its effectiveness in identifying dangerous drivers at earlier stages of the disorder is uncertain. A system of practical and effective screening for potentially dangerous drivers with dementia must be developed. Another effect of the current screening process is that it has shifted the burden of detecting potentially dangerous drivers onto the medical profession. According to Section 203 of the Ontario Highway Traffic Act, physicians must report any patient who is suffering from a medical condition that may adversely affect his or her ability to drive, including dementia. However, the health care system was not designed and physicians are not trained to screen for individuals who may be a safety hazard on the road. Further, placing the responsibility of identifying at-risk individuals on physicians can be detrimental to the patient– physician relationship (26,27). While these projections are drawn from Ontario data, similar trends can be seen in national statistics, both in Canada (28) and in the US (29). Thus it is reasonable to conclude that these projections have significance across North America. An implication of these projections is an ever-increasing number of drivers who are dangerous by reason of dementia. There is currently no effective means of identifying these individuals. Limitations and Future Directions AcknowledgementsThe authors gratefully acknowledge the assistance of Tom Brazier of the Ontario Ministry of Transportation. References1. Marottoli RA, Mendes de Leon CF, Glass TA, Williams CS, Cooney LM, Berkman LF, and others. Driving cessation and increased depressive symptoms: prospective evidence from the New Haven EPESE. J Am Geriatr Soc 1997;45:202–6. 2. Mack R, Salmoni A, Viverais-Dressler G, Porter E, Garg R. Perceived risks to independent living: the views of older, community-dwelling adults. Gerontologist 1997;37:729–36. 3. Campbell MK, Bush TL, Hale WE. Medical conditions associated with driving cessation in community-dwelling, ambulatory elders. J Gerontol 1993;48:S230–S234. 4. Jeune B. Living longer but better? Aging (Milano) 2002;14:72–93. 5. Liao Y, McGee DL, Cao G, Cooper RS. Quality of the last year of life of older adults: 1986 vs 1993. JAMA 2000;283:512–8. 6. Spillman BC, Lubitz J. The effect of longevity on spending for acute and long-term care. N Engl J Med 2000;342:1409 15. 7. Wilmoth JR. Demography of longevity: past, present, and future trends. Exp Gerontol 2000;35:1111–29. 8. Canadian Study of Health and Aging Working Group. Canadian Study of Health and Aging: study methods and prevalence of dementia. CMAJ 1994;150:899–913. 9. Ontario Ministry of Transportation. Driver Licensing Statistics. Toronto: Ontario Ministry of Transportation; 1992, 1994, 1998–2000. 10. Ontario Ministry of Finance. Ontario population projections, 1999–2028. Toronto: Ontario Ministry of Finance; 2000. 11. Hopkins RW, Hopkins JF. Dementia Projections for the Counties, Regional Municipalities and Districts of Ontario. (incorporating CSHA Prevalence Data) Geriatric Psychiatry Unit Clinical/Research Bulletin number 13. Kingston (ON): Providence Continuing Care Centre Mental Health Services; 2002. 12. Hopkins RW. Dementia projections for Canada and Ontario, and The Greater Kingston Area, 1986 - 2031. Psychogeriatric Unit Clinical/Research Bulletin number 2. Kingston (ON): Providence Continuing Care Centre Mental Health Services; 1989. 13. Hess KL. The growth of automotive transportation [essay online]; 1996. Available: http://www.klhess.com/car_essy.html. Accessed 2003 Aug. 14. AUTOSHOP-Online. Automotive history. Available: http://www.autoshop-online.com/auto101/histtext.html. Accessed 2003 Aug. 15. Lucas-Blaustein MJ, Filipp CL, Dungan C, Tune L. Driving in patients with dementia. J Am Geriatr Soc 1988;36:1087–91. 16. Fox GK, Bowden SC, Bashford GM, Smith DS. Alzheimer’s disease and driving: prediction and assessment of driving performance. JAGS 1997;45:949–53. 17. Bedard M, Molloy DW, Lever JA. Factors associated with motor vehicle crashes in cognitively impaired older adults. Alzheimer Dis Assoc Disord 1998;12:135–9. 18. Carr DB. Motor vehicle crashes and drivers with DAT. Alzheimer Dis Assoc Disord 1997;11(Suppl 1):38–41. 19. Bianchetti A, Trabucch M. Clinical aspects of Alzheimer’s disease. Aging (Milano) 2001;13:221–30. 20. Kay DW, Forster DP, Newens AJ. Long-term survival, place of death, and death certification in clinically diagnosed pre-senile dementia in northern England. Follow-up after 8 to 12 years. Br J Psychiatry 2000;177:156–62. 21. Chaussalet TJ, Thompson WA. Data requirements in a model of the natural history of Alzheimer’s disease. Health Care Manag Sci 2001;4:13–19. 22. Friedland RP, Koss E, Kumar A, Gaine S, Metzler D, Haxby JV, and others. Motor vehicle crashes in dementia of the Alzheimer type. Ann Neurol 1988;24:782–6. 23. Rizzo M, McGehee DV, Dawson JD, Anderson SN. Simulated car crashes at intersections in drivers with Alzheimer disease. Alzheimer Dis Assoc Disord 2001;15:10–20. 24. Carr DB, Duchek J, Morris JC. Characteristics of motor vehicle crashes of drivers with dementia of the Alzheimer type. J Am Geriatr Soc 2000;48:18–22. 25. Saunders P. Provincial driving regulations for seniors. Toronto: CBC News Online 2002. Available: http://www.cbc.ca/news/features/elderly_drivers.html. Accessed 2003 Aug. 26. Lloyd S, Cormack CN, Blais K, Messeri G, McCallum MA, Spicer K, and others. Driving and dementia: a review of the literature. Can J Occup Ther 2001;68:149–56. 27. Fitten JL The demented driver: the doctor’s dilemma. Alzheimer Dis Assoc Disord 1997;11(Suppl 1):57–61. 28. Statistics Canada population projections for Canada, provinces and territories 2000–2026. Ottawa: Statistics Canada; 2001. Available: http://www.statcan.ca/english/IPS/Data/91–520–XIB.htm. Accessed 2003 Aug. 29. United States Census Bureau. The older population in the United States. Washington (DC): Population Division, United States Census Bureau; 1999. Available: http://www.census.gov/prod/2000pubs/p20–532.pdf. Accessed 2003 Aug. Author(s)Manuscript received and accepted January 2004. 1. Neuropsychologist, Providence Continuing Care Centre Mental Health Services, Kingston, Ontario; Adjunct Professor, Department of Psychiatry and Clinical Supervisor, Department of Psychology, Queen’s University, Kingston, Ontario. 2. Research Assistant, Providence Continuing Care Centre Mental Health Services, Kingston, Ontario. 3. BSc Candidate, Queen’s University, Kingston, Ontario. Address for correspondence: Dr RW Hopkins, Geriatric Psychiatry Program, PCCC Mental Health Services, PO Bag 603, Kingston, ON K7L 4X3 e-mail: hopkinsr@post.queensu.ca
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