What is the magnitude of the risk associated with driving and dementia?

Facts on Normal Aging and Motor Vehicle Crashes (MVCs):

Older drivers in general have the highest risk of MVC per distance driven compared with the general population. (CMA)

Older drivers have a higher risk of injury and death after MVC compared with younger drivers. (Wang & Carr, 2004)

  • Drivers over 85 have 9 times the MVC fatality rate compared with those less than 70 years. (Wang & Carr, 2004)
  • Older drivers tend to experience a slower and less complete recovery from MVCs. (Molnar)

MVCs in older drivers have a higher risk of injuries to passengers. This may be related to the age and frailty of the person in the passenger seat.

  • MVCs in older drives have a higher risk of injuries to third parties. (Braver & Trempel, 2004).
  • 75% of MVC’s in older drivers involve more than one vehicle. (Molnar)

Dementia and MVCs

When we add dementia to this scenario, the risk is further increased.

Most people with dementia are older adults.

˜People with frontotemporal dementia or dementia with Lewy Bodies of even mild stage, may be at increased risk of MVC. The 3rd Canadian Consensus national guidelines recommend an individualized assessment of driving risk for those with Alzheimer’s dementia or dementia associated with vascular disease (Vascular Cognitive Impairment). (CCCDTD, 2007)

˜ In one study following older adults for 5 years, almost half of individuals with dementia experienced an MVC while only 10% of those without dementia experienced an MVC. (Friedland et al., 1988)

˜ Those with mild to moderate Alzheimer’s disease show a risk of MVC that is up to 8 times that of their non-demented counterparts. Reports of exact risk vary as a function of variability in study parameters such as:

  • Self report vs proxy report vs database
  • Definition of MVC
  • Population studied

Risk doubles beyond the third year of disease (Drachman et al., 1993) but there is considerable variability in the rate of progression of dementia both between and within dementia subtypes.