[Cognitive functions and driving ability of older drivers]. 
The aim of the study was to test older drivers applying for a renewal of their driver's license for cognitive impairment and to examine the outcome of a subsequent driving test.  Patients registered with general practitioners (GPs) in the County of Southern Jutland, who applied for a renewal of their driver's license because of age, participated in the study.  Data were collected from a questionnaire sent to GPs and from driving license certificates.  The test used m-mini mental state (m-MMSE) for registration of cognitive functioning was a short version of MMSE.  The number of recommended driving tests and the results of the driving test were compared during a period before and after the test was used, and compared with the result of the m-MMSE.  A total of 6,091 elderly participated in the study, 2,631 before and 3,460 after the introduction of the test.  In addition a semi-structured telephone interview with a random sample of the participating GPs was carried out.  The use of m-MMSE resulted in significantly more older drivers being recommended a driving test and significantly fewer having their driver's license renewed.  Of the older drivers who were recommended a driving test and did not have their driver's license renewed, 83% and 60% had impaired cognitive functioning.  The majority (95%) of the GPs considered the test to be a useful tool in general practice.  The results show that the use of m-MMSE when older drivers apply for renewal of their driver's license because of age, led to fewer older drivers having their driver's license renewed, and that most of them have impaired cognitive functioning.  The test is suitable for general practice.