There are myriad research papers evaluating the predictive validity of in-office cognitive assessments for the prediction of fitness to drive. A recent review of in-office cognitive assessments (Molnar, et al., 2006) showed that even the most commonly used assessments (such as the Mini Mental Status Examination, Clock Drawing, and Trails B) did not exhibit clear cut-off scores to predict on-road performance. It may be that a combination of several tests is needed but this too has yet to be validated.
Despite the absence of clear cut-off scores, information gathered during a routine office visit can help direct you as to what steps to take next. Try using this Decision Support Tool.
If you need to contact the Registry of Motor Vehciles this template letter can be used to report potentially unsafe drivers.