Don't tell me I can't drive A JOKE courtesy of “Car Talk”, National Public Radio’s hilarious motoring-advice and agony-aunt show... Two little old ladies are driving down the road. The passenger becomes alarmed when she senses her friend behind the wheel has just run through a red light. But not entirely sure, she hesitates to mention it. At the next intersection, the driver definitely goes through on red without slowing. After the third such instance, the now petrified passenger turns to her friend and says: “Mildred, you just ran three red lights!” “Heck,” exclaims an aghast Mildred. “Am I driving?” The way a person’s cognitive ability deteriorates with age is no laughing matter. Back in 1995, the National Highway Traffic Safety Administration found that, though motorists aged 70 and older accounted for only 9% of the American population, they were responsible for 14% of all traffic fatalities—and 17% of pedestrian deaths. Since then, the number of old-folk behind the wheel has risen as baby boomers edge closer to becoming septuagenarians. That is rather worrying. It could even reverse (or, at least, slow) the long-term trend towards safer motoring. The overall death rate among motorists in America has fallen steadily since 1975 (from 15 per 100,000 licensed drivers to 12 per 100,000) as a result of seat-belt laws, the crackdown on drunken driving, better infrastructure and safer vehicles all round. In contrast, the death rate among 16-year-old drivers has nearly doubled (from 19 to 35 per 100,000) over the same period. The main reasons are thought to be the heavier traffic, moving at higher speeds, and the way inexperienced teenagers have access to far more powerful vehicles than their parents had. Fortunately, teenagers mature, gain experience and put their risky behaviour behind them. Not so the elderly, who may not realise how much skill, judgment and reaction time they have lost, along with their deteriorating vision and physical strength.

With age, the brain begins to shrink, causing some of its nerve cells to lose their connections with others. At the same time, the blood flow in the brain slows down. These changes are believed to lie behind the deterioration in cognitive function—the ability to process thoughts—in elderly people.



After retirement, two out of three people suffer from some form of cognitive impairment. It starts with “senior moments”—the inability to recall the name of an acquaintance, a word on the tip of the tongue, or where the keys were put. Most compensate by making notes and relying more on calendars.



As the years roll by, such memory lapses become more frequent, and the tendency to misplace things increases. Those with mild cognitive impairment usually retain their capacity to learn, read, speak and write, but their attention span deteriorates along with their short-term memory. This can lead, eventually, to Alzheimer’s disease or other causes of dementia.



Cognitive skills are, of course, crucial for driving. So, too, is co-ordination between eyes and feet as well as eyes and hands. It is what allows the driver to steer smoothly, gauge braking distances and slot into fast-moving traffic safely. Other motor skills are necessary for depressing the pedals in the correct order, operating hand controls and turning the head to check blind spots. Most important of all is reaction time—especially the time needed to take the foot off the accelerator pedal and hit the brakes, or to jerk the steering wheel to avoid a sudden obstacle.



In a young person, reaction times can vary from 0.7 second for something expected to 1.5 seconds for a total surprise. In the latter case, extra time is needed for the brain to work out what is going on, and then to decide on a response. Though reaction times increase with age, older motorists’ greater experience and tendency to drive more slowly help compensate for the decline in motor skills.



There are no clear-cut guidelines to say when motorists should surrender their car keys. It depends so much on the individual. That said, there are some general statistics that offer assistance. For instance, drivers in their 60s are among the safest on the road—with no more fatal accidents, on average, than motorists half their age. But once they enter their 70s, their statistical chance of being killed in a car crash rises steadily.



Apart from deteriorating cognitive and motor skills, older drivers become more frail and vulnerable, which increases their likelihood of breaking bones, damaging organs and dying as a result of a crash. From their 80s onward, they start having an increasing number of more serious accidents. The Insurance Institute for Highway Safety, an industry research organisation based in Virginia that studies road accidents, reckons that octogenarians and up have higher collision rates than any other age group except teenagers. The fatality rate for drivers who are 85 and older is nine times greater than for those under 70.



Three factors contribute to age-related motoring accidents. The first is poor judgment in making turns across oncoming traffic. The second is drifting out of lane. The third is an inability to cope effectively with unexpected events. By and large, septuagenarians involved in crashes at intersections—where half tend to occur—often misjudged whether it was safe to cross or turn; octogenarians usually failed to see the vehicle they hit.



On average, then, motorists approaching their 80th year should think seriously about giving up driving. The very least they should do is discuss the matter with their family doctor, especially if they are taking drugs for chronic conditions (as is often the case with elderly people). Even over-the-counter medicines can have active ingredients—such as the antihistamines in allergy pills, or codeine in cold remedies and pain relievers—that dull motor skills and distort reaction times.



But doctors are often reluctant to tell patients to quit driving altogether—as much out of fear of alienating them, as out of concern for condemning them to a life of restricted mobility and loss of independence. Given the general lack of public transport in most parts of America, not being able to go shopping, meet friends, dine out, see a film or, indeed, visit the doctor can be a real hardship. Such activities are often the only things keeping the elderly active and alert.



In California, anyone over 70 who is renewing a driving licence is required to attend a local Department of Motor Vehicles (DMV) office every five years for both a written and a vision test. Also, doctors in California are obliged to report anyone with worrisome driving abilities to the DMV. A recent study in Canada, where similar reporting requirements exist, found that warning the licensing authority of an elderly patient’s fitness to drive resulted in a 45% drop in crashes serious enough to warrant hospital treatment.



But how do doctors identify unsafe drivers? The American Medical Association recommends a few simple tests. One is to ask a patient to walk ten feet (three metres) down a hallway, turn round and walk back. If this takes longer than nine seconds, the patient probably has a driving problem. Another test, which measures spatial processing and memory, requires a patient to connect a sequence of letters and numbers (A to 1, B to 2, C to 3, etc) scattered randomly on a piece of paper. A patient who does poorly is thought likely to cause an accident.



Unfortunately, such indirect screening procedures have had mixed results. In an ideal world, motorists over 70 would be tested directly for cognitive ability. One method that has gained favour abroad is the DriveABLE Cognitive Assessment Tool, which came out of research on fitness to drive at the University of Alberta. The test is administered by trained operatives and measures 22 variables while performing six specific tasks relevant to driving ability. The assessment is said to determine whether a driver is cognitively impaired with an accuracy of 93%.



Getting the elderly to take a test like the DriveABLE procedure in order to have their driving licences renewed is not going to happen—at least, not in the immediate future. State governments are too strapped for cash as it is. Adding a 40-minute procedure, conducted by specially trained staff using dedicated terminals, would make the whole licence-renewal process prohibitively expensive. But if, alternatively, taking the test led to the possibility of a lower car-insurance premium, your aging correspondent would be one of the first in line.