Driving Fitness in Different Forms of Dementia: An Update

Max Toepper, PhD; Michael Falkenstein, MD

Disclosures

J Am Geriatr Soc. 2019;67(10):2186-2192. 

In This Article

Abstract and Introduction

Abstract

Background/Objectives: Most forms of dementia are associated with progressive cognitive and noncognitive impairments that can severely affect fitness to drive. Whether safe driving is still possible in the single case, however, is often difficult to decide and may be dependent on both severity and type of the respective dementia syndrome. Particularly in early disease stages, Alzheimer disease dementia (ADD) and different types of non-Alzheimer dementias, such as vascular dementia (VaD), frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), and Parkinson disease dementia (PDD), might differentially affect fitness to drive.

Design: To examine the effects of severity and type of dementia on driving fitness, we conducted a systematic review with qualitative narrative synthesis, involving different driving outcomes in different forms and stages of dementia.

Setting: Literature research included MEDLINE and PsycINFO databases with a focus on the most relevant and recent publications on the topic.

Participants: The population of interest included older drivers in different stages of ADD and different forms of non-Alzheimer dementias (VaD, FTD, DLB, and PDD).

Measurements: Narrative description of driving outcomes in the population of interest.

Results: Overall, previous studies suggest that driving fitness is severely impaired in moderate and severe dementia, irrespective of the type of dementia. In milder disease stages, fitness to drive appears to be more severely impaired in non-Alzheimer dementias than in ADD, since the non-Alzheimer syndromes are not only associated with driving-relevant cognitive but noncognitive risk factors, such as behavioral or motor symptoms.

Conclusions: Based on these findings, practical recommendations are presented, including a risk evaluation for driving safety, depending on severity and type of different dementia syndromes.

Introduction

Worldwide, there are an estimated 40 million people experiencing dementia.[1] Due to demographic change, this number will further increase in the next decade and with that the number of drivers with dementia.[2] While dementia due to Alzheimer disease (ADD) is the most common cause of dementia, non-Alzheimer dementia syndromes include vascular dementia (VaD), frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), and Parkinson disease dementia (PDD). The different syndromes differ with respect to both cognitive and noncognitive impairments, such as deficits in attention, motor symptoms, fatigue, or behavioral changes. Some of these symptoms are closely related to driving skills and may, therefore, severely impair driving fitness in dementia. Nevertheless, 46% of men with very mild dementia (Clinical Dementia Rating Scale [CDR] score = 0.5) and 22% with mild dementia (CDR score = 1) still drive,[3] probably because these drivers are not aware of their deficits or just need to drive due to limited transportation alternatives. However, driving performance is frequently impaired in older drivers with dementia;[4,5] meta-analytical evidence suggests a more than 10-fold increased risk in demented drivers to fail an on-road assessment.[6] The analysis of specific driving errors shows that demented drivers forget to fasten their seatbelt, have difficulties with the identification of landmarks and traffic signs, and get lost more often.[6] They show more severe traffic violations, drive more frequently at daytime, and prefer familiar routes (avoidance behavior). Driving speed and mileage are significantly decreased.[6] Moreover, demented drivers who fail an on-road driving test show enhanced difficulties during left and right turns, in lane positioning and usage, in stopping the vehicle appropriately, and in following traffic regulations.[7] Accident risk in patients with dementia is 1.77-fold increased within the 3 years before diagnosis.[8] After diagnosis, it appears to decrease, probably due to protective interventions limiting driving in older people diagnosed with dementia.[4,8]

Together, the above results indicate that driving fitness is frequently impaired in dementia. Whether a driver with dementia is still able to drive in the individual case, however, is often hard to decide and leaves a great deal of uncertainty among practitioners. Empirical studies, therefore, get increasingly important. In the last couple of years, a great number of relevant studies were published, providing new, important, and valid data on driving fitness in dementia. The current article provides an overview of the most recent and relevant earlier findings, resulting in an evaluation of driving safety dependent on the severity and type of dementia. Particularly in early disease stages, ADD and different types of non-Alzheimer dementia might differentially affect fitness to drive.[9] Due to early driving-relevant cognitive and noncognitive risk factors, we expect that fitness to drive is impaired more severely in the non-Alzheimer syndromes than in ADD.

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