Driving and dementia: A delicate balance

Mary Beth Wightonof Southampton, Ont.,remembers the day four years ago when her doctor delivered her a devastating one-two combination of bad news.

"She said, 'I am sorry to tell you but you have probable frontotemporal dementia.' She explained what it was and then she said, 'and there is another thing that I need to do immediately, which is to revoke your driver's licence ... effective immediately.'"

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Wighton, who was then 44,was still in the early stages of dementia.

But research is increasingly showing that even mildcognitiveimpairments (MCI), short of dementia,have the potential tobea problem on the road.

MeganHird, a researcher at St. Michael's Hospital in Toronto, carried outtests on 22 patients with MCI and 17 healthy individuals, using driving simulators and brain scans.

"The results of our study showed that patients with mild cognitive impairment ... exhibited increased risky driving errors, such ascollisionsand lane deviations, compared to cognitively healthy drivers," she told CBC News.

"This was particularly the case during morecognitivelydemanding aspects of driving, such as left-hand turns at a busy intersection."

3 times more driving errors

Her study, presentedThursday at the Alzheimer's Association International Conference in Toronto, suggeststhat drivers with mild impairmentin their cognitive ability but who haven't been diagnosed with Alzheimer's disease or any other kind of dementia weremuch more likely to commit majordriving mistakesthan healthy drivers. In some cases, the error rate was triple.

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While people with MCI are at an increased risk of laterdeveloping Alzheimer's disease or another form of dementia, their current impairments indaily behaviour are moresubtle so people with MCI often continue to carry out all of their routine daily activities, like working, managing their finances, cooking ... and driving.

The problem, researchers say, is that driving is an especially complex task, involving attention, memory, executive functioning and the processing of visual information about where objects are.

Currently, doctors are required in manyprovinces to report the medical condition of someone they think shouldn't be driving to the relevant transportation ministry. But if the cognitive deficits are minor, thatmay nothappen.

Hirdsays many doctors don't feel comfortable assessing the driving fitness of their patients. "It's a very difficultconversation to have with someone," sheacknowledges.

Senior drivers

Most provinces require senior drivers,usually those 75 or 80 or over,to undergo some kind of visionand/or written test every two years to assess their driving ability. Depending on the outcome of that initial assessment, a road test may be required.

While driving is not a right, losing one'slicence can be a major life-changer.For instance, someone with a mild cognitive impairment or in the early stages of Alzheimer's disease may not qualify for door-to-doormunicipaltransitservices, because they're not recognized as disabled.

Screening tools

The Canadian Medical Association publishesa "driver's guide" for its membersthat doctors canuseto detect and assess health conditions that can affect their patients' ability to drive, including dementia and mild cognitive impairment.

Hirdsays the ultimate goal of her research is tohelpdeveloptools that doctors can use to screenpeople who may be at risk, because she says there are currently "no validtools" to help them assess the driving fitness ofpatients with mild cognitive impairment.

"Because [driving] is such an important source of independence, you don't want to be taking away someone's licence when they are still able to drive safely," Hird says.

"We need to achieve a balance between maintaining patient independence [and] the safety of the driver and the general public."