Medical Conditions and Driving

According to the National Highway Traffic Safety Administration (NHTSA), human error causes as many as nine out of every 10 highway car accidents. Many different medical conditions can affect driving. Patients and their families should be aware of what issues can create unsafe driving conditions and discuss any concerns with their doctor. The connection between some medical issues and driving difficulties is surprising.

Blood Pressure

• Numerous studies indicate hypertension, or high blood pressure (>140/90), affects cognitive performance, especially the ability to concentrate and pay attention to drive safely. The NHTSA refers to the American Heart Association numbers indicating one in four American adults suffer from hypertension and yet 40 percent of them receive inadequate treatment or no treatment at all. Drivers who don't have their hypertension under control should avoid driving due to the difficulties in concentration and reasoning that often accompany high blood pressure.

Seizures

• Doctors treating patients experiencing seizures and similar neurological events such as transient ischemic attacks typically must report such information to the motor vehicle department. Because such events usually occur very suddenly and create complete loss of control in the patient, neurological events like these cause concern when the patient is driving. Epileptics and others experiencing such events can drive if their medication is effective, however. The American Medical Association (AMA) recommends patients remain seizure-free for at least three months before driving.

Psychiatric Disorders

• Psychiatric illnesses including depression, bipolar disorder and anxiety disorders affect concentration levels and the ability to react quickly and appropriately while driving. Patients should avoid driving until their physicians feel they have been stabilized, never driving when they feel suicidal or manic.

  Psychosis presents a particular danger. The NHTSA compiled studies regarding schizophrenics and car accidents, and when the amount of time such patients spend driving is correlated to crashes, statistics show that schizophrenics are twice as likely to be involved in accidents (See Reference 1).

Sleep Disorders

• Two sleep disorders, apnea and narcolepsy, may have significant impact on driving ability. Apnea affects the airway during sleep, disrupting the cycle and creating excessive daytime sleepiness and cognitive impairment. Narcolepsy is sometimes characterized by such fatigue but also hallucinations and cataplexy, the sudden loss of muscle control. The NHTSA compilation indicates a clear relationship between these sleep disorders and an increased chance for impairment while driving, which may lead to an accident.

Medications

• Rather than the medical condition itself, the prescription may sometimes interfere with driving. Many drugs including antidepressants, antihistamines for allergies, blood pressure medications and sedatives such as sleep aids sometimes cause drowsiness, deccreasing reaction time behind the wheel. The AMA suggests patients refrain from driving during initial use of a new prescription until they are sure how they react to the drug. Narcotic analgesics and painkillers, such as codeine and Darvon, may impair judgment even when the patient experiences no noticeable side effects, so the AMA suggests refraining from driving while using them.