Impaired Drivers

White Paper on Impaired Drivers 


The Physician's Dilemma 


The preferred method of transportation for Americans continues to be the private automobile. In many instances, public transit and private transportation services are either unavailable, unaffordable, or unacceptable for reasons of convenience, accessibility, or perceived lack of security. More than 70 percent of persons age 75+, the fastest growing segment of our population, live in suburbs and small towns that have been designed to accommodate automobile use. Housing areas are typically not close to shops and services, so walking is not often possible.

As we grow older, we each are at increasingly greater risk of experiencing impairment in the various functional capabilities needed to drive safely, whether because of medication, disease, or ultimately, the normal aging process. These include the visual abilities needed to detect hazards, while effectively directing attention to critical driving tasks in the face of mounting distractions.


Also essential are the perceptual skills needed to accurately judge gaps in traffic, and the cognitive functions necessary to make rapid and appropriate maneuver decisions. Also important are physical abilities, including head and neck flexibility to scan for safety threats before turning, backing up, changing lanes, or merging, as well as arm and leg strength and stamina needed to effectively control the vehicle under normal and emergency response situations. To safely operate a motor vehicle demands a higher level of functional ability and functional integration than any other activity of daily living. (7)

Whether an impairment results from normal aging, or from diabetes, dementia, vision loss, hearing loss, medication, or any of a number of diseases that become more prevalent as we grow older, there is reason for serious concern that the result will lead to increased crash risk.

Department of Motor Vehicle studies have found that unrestricted drivers with certain medical conditions have significantly higher crash and conviction rates than control groups without impairments. Given current practices and demographic trends, analysts project a sharp increase in both the number and proportion of traffic fatalities related to the frailties of aging over the first quarter of the 21 st century – even to an extent that exceeds alcohol-related fatalities. Therefore, as background for this paper, it may be asserted that driving while impaired due to functional loss deserves the same recognition as a public health concern as other types of impaired driving.

A number of medical conditions may have an impact upon the ability of an individual to drive.

In some instances age is used as a determinant to trigger medical examinations and re-examinations in the licensing process. There are a number of reasons for singling out older drivers as high risk groups. First, in normal aging, there is frequently some psychomotor slowing that may affect driving ability. Second, age-related decreases in reaction time, divided attention (performing two or more simultaneous tasks), and selective attention (filtering out irrelevant information) have been documented. Third, older adults may be at increased risk for medical conditions that may compromise their ability to drive safely. Even though there is some deterioration of mental, motor, and sensory functions with increasing age, it is not known to what.extent this affects driving performance, and elderly persons usually drive safely. Reviews of theresearch, in fact, show that little data support the assumption that older drivers are, per se, unsafe drivers. According to current statistical trends, the crash rate per miles driven among older adults is not as high as it is among drivers less than 25 years of age. Furthermore, there is some limited research to suggest that healthy older drivers pose less of a threat to others and commit fewer errors on standardized road tests compared to younger drivers. Many older drivers also avoid serious driving problems because they recognize their limitations and adjust their driving by avoiding driving at night, in heavy traffic, and in bad weather. On the other hand, even if self-regulation is a common practice among older drivers, it is not a foolproof method of protecting public safety, especially if one considers that aging drivers with disorders affecting mental functioning (e.g. dementia), for example, may lack insight into their driving difficulties.

Another factor to consider is that older drivers show the greatest variability of any age group, with some older drivers possessing adequate driving skills until a very late age, and others singled out relatively early as being high-risk drivers. Performance is impaired only after a significant loss of function, perhaps because of the onset of a significant medical condition combined with age-associated inefficiencies that interact to significantly impair driving performance. The legal requirements for driver licenses may need updating to ensure that only those adults, of any age, who are at high risk for unsafe driving are required to undergo re-evaluation.

High risk factors might include the presence of vision, psychological, physical or other medical problems. While specific conditions might affect driving skills regardless of age, many are more common and prevalent with increasing age.


Full text: MSSNY White Paper on Impaired Drivers.