Driving and Alzheimer's disease: the risk of crashes.

We designed this questionnaire-based study to determine the risk of auto crashes among Alzheimer's disease (AD) patients who continued to drive after the onset of AD, compared with normal age-matched control subjects and other drivers' statistical records. While ultimately all AD patients will become incapable of driving, it is not known whether, under current licensing regulations and self-imposed limitations, patients with AD present a definably increased risk of being involved in crashes, and if so, the relative magnitude of the risk and at what point in the course of the disease the risk may become significantly increased. We administered a brief questionnaire to the caregivers of 130 AD patients and to 112 age-matched, nondemented control subjects and their spouses. Annual rates of occurrence and severity of all crashes, and of crashes reported to the authorities, were determined from spousal or other caregiver responses. For all years of driving following the onset of dementia, AD patients had a mean of 0.091 reported crashes per year compared with matched controls, who had an average of 0.040 reported crashes per year in the same period of time. The average number of crashes per year changed with each year of driving following the onset of AD, with considerably lower reported crash rates during the initial years of dementia: in year 1, the crash rate was 0.068; in year 2, 0.097; in year 3, 0.093; in year 4, 0.159; in year 5 and beyond, 0.129.(ABSTRACT TRUNCATED AT 250 WORDS)