context: Parkinson's disease is a type of movement disorder that can significantly impair driving skills, cause safety concerns, and force many people with the condition to stop driving a car. That's because the primary symptoms of Parkinson's disease can seriously interfere with the complex task of driving a car. These symptoms are: Tremor -- trembling in the hands, arms, legs, jaw, or head Rigidity -- stiffness of the limbs and trunk Bradykinesia -- slowness of movement Postural instability -- impaired balance In addition, some people with Parkinson's disease may develop cognitive impairment: defects in thinking, language, and problem-solving. Many people with early Parkinson's disease can safely continue driving, especially if symptoms are controlled. Because Parkinson's disease worsens over time, however, many people with Parkinson's disease eventually will need to give up driving a car and rely on other forms of transportation. In American culture, driving is strongly associated with self-reliance and freedom. Some people with the condition may recognize the safety risks and voluntarily agree to limit or stop driving a car. But others may be unable to acknowledge that their driving skills are seriously impaired and insist on driving despite the safety risks to themselves and others. Parkinson's disease symptoms vary from patient to patient. They can range from mild to severe. But even in mild cases, common symptoms such as shaking in the arms, hands, or legs, impaired balance, and slowed physical and mental responses can affect driving skills. Episodes of tremor, for example, often begin in a hand or a foot and can affect the ability to operate a car's controls. Rigidity can result in jerky motions while steering. Slow movement can interfere with braking in heavy traffic or ability to quickly react to road hazards. Postural instability often results in a stooped posture in which the head is bowed and shoulders are drooped, further reducing drivers' awareness of their surroundings. For many people with early Parkinson's disease, medications can reduce symptoms. But medications may have side effects, such as drowsiness, that can affect driving as well. It can be difficult for doctors to devise a medication plan that reduces the primary symptoms of Parkinson's disease and allows some patients to drive without causing side effects that make driving a car even more dangerous. If you have early-stage Parkinson's disease and hope to continue driving as long as possible, it's essential to keep up regular exercise that maintains the muscle strength you need to operate a vehicle. It's also essential to meet with your doctor and ask him or her about: Medications and other treatment, such as deep brain stimulation, that may treat your symptoms. Medication side effects that can interfere with driving safety. Referral to a center or specialist who can give you an off-road driving test. To find a local specialist, contact the Association for Driver Rehabilitation Specialists at 866-672-9466 or visit its website. Your local hospital or rehabilitation center may help you find an occupational therapist who can assess your driving skills. In addition, your state's department of motor vehicles ( DMV) may offer driver evaluations. If you have early-stage Parkinson's disease and early-stage or mild dementia -- and wish to continue driving -- you should seek an immediate evaluation of your driving skills. People with moderate-to-severe dementia should not drive. Some states automatically revoke the licenses of everyone diagnosed with moderate-to-severe dementia. If you pass a driving evaluation, it doesn't mean that you can continue driving indefinitely. Because symptoms of Parkinson's disease and dementia usually worsen over time, it's important to be re-evaluated every six months and stop driving if you do not pass the test. If a loved one has been diagnosed with Parkinson's disease -- with or without associated cognitive impairment -- certain day-to-day behavior can indicate an inability to drive safely. Watch carefully for the following signs: Poor coordination Difficulty judging distance and space Disorientation in familiar places Inability to handle multiple tasks Inattention to personal care Increased memory loss, especially short-term memory loss Frequent mood swings, confusion, and irritability Decreased ability to process information, solve problems, and make decisions Even if an independent evaluation shows that your loved one can drive safely, it's still important to continue monitoring his or her driving skills to detect problems that could lead to a serious accident. Warning signs include: Driving too slowly Stopping in traffic for no apparent reason Ignoring traffic signs Getting lost along a familiar route Difficulty executing turns and lane changes Drifting into other traffic lanes or driving on the wrong side of the street Forgetting to signal or signaling incorrectly Not noticing other vehicles, pedestrians, or road hazards Becoming drowsy or falling asleep behind the wheel Parking inappropriately Getting tickets for traffic violations Getting into near-miss situations, fender benders, or other accidents Any of these warning signs could indicate that it's time for your loved one to stop driving. It's important to discuss any concerns you have with your loved one and his or her doctor. Frank discussions with family members and doctors are often enough to convince people with Parkinson's disease to modify their driving. Some people may need additional input from a support group, lawyer, or financial planner to ease the transition. Some people with Parkinson's disease can continue driving under strict guidelines, although the long-term goal will still be to eventually stop driving. Guidelines for limited driving may include: Drive only on familiar roads Limit drives to short trips Avoid rush-hour traffic and heavily traveled roads Restrict drives to daylight hours during good weather It's important for family and friends to find ways to help their loved one reduce their need to drive. These include arranging for groceries, meals, and prescriptions to be delivered to the home, or for barbers or hairdressers to come to the home. It's also important to help your loved one become accustomed to using alternate methods of transportation, such as: Rides from family and friends Taxi cabs Shuttle vans and buses Public buses, trains, and subways Walking Your local Area Agency on Aging can help you find transportation services for a loved one. Eldercare Locator, a service of the U. S. Administration on Aging, can also assist. Its phone number is 800-677-1116, If your loved one refuses to voluntarily limit or stop driving, despite a demonstrated need to do so, you may need to take more aggressive steps, such as: Hiding the car keys Disabling the car Either selling the car or moving it out of sight Contacting your local DVM Make sure your loved one's doctor is aware of your concerns. He or she should be able to help.