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Massachusetts Medical Society's
Physician Focus

May 2011

Medical Perspectives On Impaired Driving


  • Impaired driving can affect anyone at any time and result from different factors: alcohol, distracted driving, diminished physical and mental abilities, reduced vision, taking medications – or combinations of those.

  • Fatigue plays a big role in impaired driving: a Centers for Disease Control (CDC) study says one in 20 drivers reported ‘driving drowsy’ – dozing off while behind the wheel.

  • Every day, 32 people in the United States die in motor vehicle crashes that involve an alcohol-impaired driver.

  • The cost of medical care and lost productivity associated with injuries from motor vehicle crashes exceeds $99 billion a year, with direct medical care amounting to $17 billion, according to the CDC.

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Massachusetts Medical Society

Centers for Disease Control

National Highway Traffic Safety Administration


AAA Foundation for Traffic Safety

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Impaired Driving PSA

From left: Bruce Karlin, M.D., Janet Jankowiak, M.D., Elizabeth Roaf, M.D
hi-res photo
promo slide

Prompted by an increasing incidence of “distracted driving” and renewed questions about the abilities of older drivers, the topic of impaired driving has reached the forefront of discussions about public health and safety. Yet impaired driving is not a new topic. Physicians have recognized it for more than a decade – but from a medical perspective.

Driving a motor vehicle is something that most people take for granted. Yet many fail to remember that operating a motor vehicle is a complicated task requiring skill, attentiveness, and physical, mental and cognitive abilities, as well as knowledge of the rules of the road.

“Driving has become deceptively easy,” says Janet Jankowiak, M.D., a geriatric and behavioral neurologist. “It really is an example of multi-tasking. It’s not just knowing the rules of the road, but being able to cope with the unexpected things that may happen.”

Dr. Jankowiak and Elizabeth Roaf, M.D., a physical medicine and rehabilitation specialist, were guests on Medical Perspectives on Impaired Driving, the May edition of the Massachusetts Medical Society’s Physician Focus health care program. The two physicians were members of the Massachusetts Medical Society’s Working Group on Impaired Drivers, with Dr. Roaf chairing the group. They discussed the topic in detail with host Bruce Karlin, M.D., a primary care physician.

“There are medical conditions that can impact your ability to drive safely,” says Dr. Roaf, “and there are factors you have control over that aren’t necessarily medical. Then there’s the interplay of the two.”

Indeed, medical conditions like arthritis, seizures, cardiovascular or respiratory disease, or sleep disorders can reduce one’s ability to operate a vehicle. Medications can have an effect as well.

A leading cause of impaired driving, of course, is alcohol, which alters judgment and reaction time. Nearly one-third of all traffic-related deaths result from alcohol-impaired driving crashes. It doesn’t take much to become impaired: less than one drink an hour can put you over the legal limit. Older people can be particularly susceptible, as changes in metabolism from aging reduce the body’s ability to process alcohol.

Dr. Roaf expresses increasing concern with the interplay of alcohol with other conditions, like fatigue, use of medications, or medical conditions. “The combination of these,” she says, “really could cause catastrophic consequences.”

Some medications, for example, can lead to muscle weakness or drowsiness, restricting reaction time. Combine that with fatigue, bad weather, or a weakened physical condition, and one has the potential for a serious, if not deadly, outcome. Conditions like back or neck pain or muscular-skeleton problems can also affect driving ability by reducing reaction time, peripheral vision (which naturally declines with age), and physical abilities.

Dr. Jankowiak says part of the issue regarding impaired driving relates to a person’s “executive function” – the ability to plan, organize, initiative behavior, be mentally flexible, and problem solve.” This “executive function” begins to decline as people age, a reason why older drivers tend to have more accidents. The concept also applies to teenage drivers, except in reverse: with teens, “executive function” isn’t fully developed yet, one reason why teen accident statistics are similar to those of the older driver.

“Patients have the responsibility to make sure they’re medically fit to drive,” says Dr. Roaf. “Talk with your doctor if you have concerns. Get your routine health screenings for vision, heart, lungs, neurological and muscular systems. And take care when you’re driving. It’s much more dangerous than you realize.”

Watch the accompanying video for the complete conversation, including more details on older drivers, peripheral vision, distracted driving, and medical conditions that can affect operation of motor vehicles.

MMS/Richard Gulla