As the population ages, more and more of America's elderly face the agonizing decision of when to stop driving. "In a culture that relies heavily on the automobile, this is a difficult decision," says Dr. Samuel Chirman, a general medicine physician at the UC Davis Medical Center. California law requires physicians to report patients with Alzheimer's disease and related disorders to health department officials who also notify the Department of Motor Vehicles. "Basically any condition that impairs a person's ability to drive safely must be reported," Chirman says, "but a problem of increasing concern is dementia in connection with Alzheimer's disease." Other reportable conditions include alcoholism, epileptic seizures, multiple sclerosis, strokes, severe arthritis, problems associated with balance or confusion, and medications with side effects. Not all reportable conditions result in an automatic loss of driving privileges. Some problems fluctuate, requiring periodic reassessment.