For patients who have moderate cognitive problems or sharp declines in mental performance, the practitioner should recommend on-road testing only when necessary. Unnecessary testing due to injudicious screening can lead to excessive costs. Furthermore, because no evaluation is perfect, unfounded restrictions for capable elderly drivers may result, and such limitations can induce functional decline. The three major types of attention are selective, divided, and sustained. The driver must selectively disregard noise or other contaminating influences.
Divided attention is the ability to process two or more stimuli at once and respond appropriately.
For example, when the driver is approaching an intersection or merging onto a freeway, he must divide his attention between signaling the turn and accelerating into traffic. Divided attention and sustained attention are clinically important, yet no reliable test is available for either measure. Although functional assessment is usually considered more relevant than a medical diagnosis, certain medical conditions and the use of certain drugs should be considered when a person's ability to drive is evaluated. When beginning treatment with a new drug that could affect motor, visual, or cognitive function, patients should avoid driving for 1 to 2 days to be sure no adverse effects occur. Patients should refrain from driving for about 1 month after an uncomplicated myocardial infarction or a coronary artery bypass graft operation or for 3 to 4 days after angioplasty.