Driving tests with patients.

Mental illness and the use of psychotropic drugs are considered to influence driving skills of patients. However, studies which indicate the relative contributions of these factors are rare. It is emphasized that for measuring the effects of psychotropic drugs on driving performance of patients, real driving tests are needed. Actual driving and psychomotor performance of patients receiving diazepam, and patients and healthy volunteers receiving mebhydrolin were measured to illustrate the use of real driving tests. The results of both studies are discussed in terms of problems associated with the application of these tests. Patient recruitment is considered to be a major problem. To draw conclusions under these circumstances is extremely difficult, but still acceptable in comparison with the limitations and methodological difficulties of the more commonly used laboratory tests. Some guidelines for driving tests with patients are given.