Driving behaviors in early stage dementia: A study using in-vehicle technology

Abstract

According to the Alzheimer's Association (2011), (1) in 8 people age 65 and older, and about one-half of people age 85 and older, have Alzheimer's disease in the United States (US). There is evidence that drivers with Alzheimer's disease and related dementias are at an increased risk for unsafe driving. Recent advances in sensor, computer, and telecommunication technologies provide a method for automatically collecting detailed, objective information about the driving performance of drivers, including those with early stage dementia. The objective of this project was to use in-vehicle technology to describe a set of driving behaviors that may be common in individuals with early stage dementia (i.e., a diagnosis of memory loss) and compare these behaviors to a group of drivers without cognitive impairment. Seventeen drivers with a diagnosis of early stage dementia, who had completed a comprehensive driving assessment and were cleared to drive, participated in the study. Participants had their vehicles instrumented with a suite of sensors and a data acquisition system, and drove 1–2 months as they would under normal circumstances. Data from the in-vehicle instrumentation were reduced and analyzed, using a set of algorithms/heuristics developed by the research team. Data from the early stage dementia group were compared to similar data from an existing dataset of 26 older drivers without dementia. The early stage dementia group was found to have significantly restricted driving space relative to the comparison group. At the same time, the early stage dementia group (which had been previously cleared by an occupational therapist as safe to drive) drove as safely as the comparison group. Few safety-related behavioral errors were found for either group. Wayfinding problems were rare among both groups, but the early stage dementia group was significantly more likely to get lost.

Introduction

According to the Alzheimer's Association (2011), (1) in 8 people aged 65 and older, and about one-half of people age 85 and older, have Alzheimer's disease (AD) in the United States (US). The number of people age 65 and older will more than double in the next 25 years, with a threefold increase for those age 80 and older (Herbel et al., 2006). In the next 4 decades, those age 80 and older are expected to increase from 15 percent of all older people in the United States to 24 percent of older Americans (Alzheimer's Association, 2011). This increase is projected to result in 15 million more oldest-old people living in the US and these individuals are the ones most at risk for developing Alzheimer's disease (Alzheimer's Association, 2011).

While it might be assumed that individuals with dementia would stop driving after onset of symptoms, it is estimated that around one-third of drivers with dementia continue to drive (Silverstein, 2008). Most drivers are early in the disease process when cognitive deficits are generally mild (Adler and Kuskowski, 2003) and changes to driving performance are minimal. Nonetheless, drivers with dementia are one of the groups considered at greatest risk for unsafe driving performance (Langford et al., 2007). Yet, decisions to enforce driving cessation are not straightforward and pose a difficult challenge to family members, licensing authorities, and health care professionals.

Compared to the general driving population, drivers with dementia are at an increased risk of unsafe motor vehicle operation (Man-Son-Hing et al., 2007). Problematic driving behaviors include becoming lost in familiar areas (Silverstein et al., 2002, Uc et al., 2004), incorrect turning (Uc et al., 2005), impaired signaling (Duchek et al., 2003), decreased comprehension of traffic signs (Carr et al., 1998), and lane deviation (Uc et al., 2005). Crashes, while infrequent, are also of concern for drivers with dementia, whose crash risk is two to five times that of unimpaired older drivers (Charlton et al., 2003). Furthermore, driving skills predictably worsen (Adler et al., 1999) and will ultimately require individuals with dementia to stop driving (Adler et al., 2005).

Driving decisions need to be made not on diagnosis but on an assessment of the dementia's progress and the disease's effects on functional abilities (Duchek et al., 2003, Eby et al., 2009a, Eby and Molnar, 2010). Unfortunately, there is little consensus on the means to make this assessment. A review of studies that measured driving competency of drivers with dementia found a wide array of different assessment approaches; even where common protocols were used, there were different conclusions about their usefulness and validity (Reger et al., 2004). Road tests seem essential to evaluating driving ability; however, on-road evaluations by themselves have not been able to fully answer questions of driving competency. Because driving is an over learned task, standard road tests with step-by-step instructions do not necessarily test the skills or expose errors commonly made by an experienced driver (Odenheimer, 1993). Another approach to assessing driving skills in individuals with dementia uses a driving simulator. Learning to use a simulator, however, can be difficult for drivers with dementia even when given time to adapt to the setting (Cox et al., 1998). An additional complication of using a simulator to assess driving skills is the fact that older adults, in general, are more likely than younger people to experience simulator sickness (Brooks et al., 2010). Furthermore, individuals with dementia retain abilities that are over learned and thus, actual driving skills may be better than those assessed under the artificial conditions of a simulator. Neuropsychological tests have frequently been used to predict fitness to drive, often in studies that incorporate on-road or simulator evaluation, although their association with driving impairment and crash risk is at best moderate. Such studies often report statistically significant associations, but their size and variability suggest that no single protocol can confidently indicate for a specific patient the impairment threshold for non-driving (Reger et al., 2004). As a result of current assessment inconsistencies and shortcomings, some drivers with dementia may remain on the road longer than is safe while other drivers may cease prematurely. Improved procedures for assessing driving risk are urgently needed (Reger et al., 2004).

Recent advances in sensor, computer, and telecommunication technologies provide a method for automatically collecting detailed, objective information about a person's driving performance (e.g., LeBlanc et al., 2006, LeBlanc et al., 2007). This technology, placed unobtrusively in a driver's vehicle, can be used to study the driving behavior of individuals diagnosed with early stage dementia. The objective of this project was to use in-vehicle technology to describe a set of driving behaviors that may be common in individuals with early stage dementia (i.e., a diagnosis of memory loss) and compare these behaviors to a group of drivers without a diagnosis of cognitive impairment.