If you are concerned about an Alzheimer’s patient’s ability to drive, look for signs of unsafe driving such as forgetting how to locate familiar places, failing to observe traffic signs, making slow or poor decisions in traffic, driving at an inappropriate speed, or becoming angry or confused while driving. Write your observations down and share them with the person, other family members, and healthcare professionals. It is also a good idea to check driving regulations in your state. In some areas, such as California, the physician must report a diagnosis of Alzheimer’s to the health department, which in turn notifies the department of motor vehicles, who may then revoke the person’s license. Your local chapter may have information available on state driving regulations.
(Source: Alzheimer's Association)