How to investigate fitness to drive of patients with Alzheimer’s dementia

Introduction In early stages of Alzheimer’s dementia, some patients are still fit to drive, but others are not (Ernst et al., 2010). Therefore, fitness to drive should be evaluated when people have been diagnosed with dementia. The gold standard to determine fitness to drive is an on-road assessment (Freund et al., 2002), but it remains difficult to decide which patients should be advised to do such a time and effort demanding on-road driving assessment and which not (Kay et al., 2012), as sensitive alternative instruments are lacking. The goal of the present study is to develop a validated fitness-to-drive test battery for drivers with Alzheimer’s dementia in a clinical setting. MethodPatients with Alzheimer’s disease (n=81) were screened on fitness-to-drive using interviews with the patient and an informant, a neuropsychological assessment and rides in a driving simulator. All participants also completed an on-road assessment. The validity of the fitness-to-drive assessment procedure was examined, in particular regarding its accuracy in predicting on-road driving performance (gold standard).ResultsWith information from the clinical interviews only, 83.5% of the patients were classified correctly as fit or unfit to drive. The best predictors from the clinical interviews were two sub-scores of the Clinical Dementia Rating (Morris, 1993), the patients’ judgements about their own driving safety and recent driving experience. When using neuropsychological tests or driving simulator rides, respectively 90.5% and 86.1% of the patients were classified correctly. Four neuropsychological tests were most predictive, i.e. the Mini-Mental State Examination (Folstein et al., 1975), an auditory reaction time test (Prieler, 2008), a hazard perception test (Vlakveld, 2011), and a test for knowledge of traffic rules. In the driving simulator, slowing down for intersections, the number of collisions and a merging manoeuvre provided predictive information. A combination of the predictions based on the interviews, neuropsychological tests, and driving simulator rides resulted in a correct classification of 97.4% of cases.DiscussionMeasures from clinical interviews, neuropsychological assessment and driving simulator rides were found to be predictive of on-road driving. The best prediction of fitness to drive was achieved when combining all three types of assessments. The screening instrument will serve both patients affected as well as the assessors and others involved in the decision making process. ReferencesErnst J, Krapp S, Schuster T, Förstl H, Kurz A, Diehl-Schmid J. (2010). Car driving ability of patients with frontotemporal lobar degeneration and Alzheimer's disease. Nervenarzt. 81(1):79-85.Folstein MF, Folstein SE, McHugh PR. (1975). "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 12(3):189-98.Freund B, Gravenstein S, Ferris R, Shaheen E. (2002). Evaluating driving performance of cognitively impaired and healthy older adults: a pilot study comparing on-road testing and driving simulation. J Am Geriatr Soc. 50(7):1309-10. Kay LG, Bundy AC, Clemson L, Cheal B, Glendenning T. (2012). Contribution of off-road tests to predicting on-road performance: a critical review of tests. Aust Occup Ther J. 59(1):89-97. Morris JC. (1993). The Clinical Dementia Rating (CDR): current version and scoring rules. Neurology. 43(11):2412-4.Prieler J. (2008). Manual RT: Reaction test. Version 31. Schuhfried GmbH, Mödling.Vlakveld WP. (2011). Hazard anticipation of young novice drivers; assessing and enhancing the capabilities of young novice drivers to anticipate latent hazards in road and traffic situations. PhD thesis. University of Groningen. SWOV Institute for Road Safety Research, Leidschendam