This is a longitudinal research project which examined changes in on-road driving performance and changes in cognition among actively driving subjects with mild Alzheimer's disease. It is well recognized that dementia is a risk factor among the elderly for motor vehicle crashes and fatalities. Degenerative dementias such as Alzheimer's disease, because of their progressive nature, eventually lead to driving incompetence in all cases. A critical question that faces clinicians in everyday practice is when to advise patients with early disease to abstain from driving.

Because patients with Alzheimer's disease may still be competent to drive if their dementia is in its earliest and mildest stage, and because driving is an important factor in maintaining autonomy for elders, licenses should not be revoked based on arbitrary decisions about one's memory ability. Annual road testing for driving competence of all elders or even all elders with dementia is neither practical nor economical. Therefore, an effective screening instrument is badly needed. Knowledge about the actual driving impairments that occur in dementia patients that lead to hazardous driving and how they relate to changes in neuropsychological function over time is critical to the development of a valid screening tool.

Drivers with early stage Alzheimer's disease were enrolled in this study and followed every six months over two to three years. A validated road test protocol was administered by a professional driving instructor. Computerized neuropsychological tests of visual perception, visual attention, and executive function were administered concurrently. It was predicted that the earliest evidence of driving impairment would be associated with disturbances in visual perception and attention. In more advanced stages of dementia, when subjects are most likely to be judged as incompetent drivers, there would be prominent deficits in executive function as well.

The longitudinal design of this study has given important insights into the evolution of driving impairment among Alzheimer's disease patients and will assist in the future development of screening tests to identify hazardous drivers who would be likely to fail a performance based road test.

Funded by the National Institute on Aging

Naturalistic Assessment of the Driving Ability of Cognitively Impaired Elders

Principal Investigator: Brian R. Ott, MD

This research that will examine the driving abilities of elderly drivers with and without cognitive impairment related to probable or possible Alzheimer’s disease. It will expand our knowledge about cognitively impaired older drivers and extend the observations made during our prior research studies from RO1#AG16335, entitled “A Longitudinal Study of Hazardous Drivers With Dementia.” Specifically, we will examine 150 older drivers with mild Alzheimer’s disease (N=50), questionable or mild dementia (N=50), and no cognitive impairment (N=50). We will compare performance on specific computerized measures of visual attention and executive function to digital camera recordings of subjects in their own cars, driving in their natural environments. We will perform a similar analysis of the computerized measures for the same subjects completing an extended version of the Rhode Island adaptation of the Washington University Road Test. Driving outcomes will be scored on continuous rating scales as well as global assessments of safety. These assessments will be done at baseline and repeated at one year.

This will be the first study of its kind to directly examine cognitively impaired elders in their natural driving environments. We will compare driving performance in the structured road test setting to performance in the unstructured natural setting. This comparison will help us to understand the validity of the road test as a ”gold standard” for driving assessment in this population. Furthermore, we will characterize and quantify the types of errors made in driving, by use of a reliable rating scale of the video recordings in both familiar and unfamiliar driving environments. We predict that video recordings in the natural environment will be more sensitive for detection of driver errors.

Secondary goals of this research will include examination of the accuracy of family members and caregivers in predicting driving performance ratings by a professional driving instructor in the natural and road test settings.

Ultimately, this research seeks to develop selected computerized measures for pilot testing as a screening measure in the clinician’s office practice or in a department of motor vehicles. Also, we will gain much needed insight into the relevance of formal road tests to actual day to day driving performance by cognitively impaired older drivers. In this way, knowledge gained from the longitudinal study will further advance our understanding of the very important and vexing problem of drivers with early dementia, producing some potential solution to the identification of those at greatest risk for hazardous driving. Contact Lindsay Miller at 444-0789.

Funded by the National Institute on Aging