Vision, Cognition, and Mobility Challenges for Elderly Drivers

US Pharm. 2007;1:36-40.

Compared with younger drivers, older drivers are less likely to drink and drive and to cause an accident resulting in a fatality.¹ However, the safety of older drivers is a public health concern, since motor vehicle accidents are a leading cause of injury-related deaths in adults 65 and older. ^2,3 Furthermore, the fatality rate for drivers 85 and older is nine times higher than that of drivers ages 25 to 69.³ Older drivers are considerably more fragile than their younger counterparts and are therefore more likely to suffer a fatal injury in the event of a crash.

Many older adults report that maintaining the ability to drive represents independence, freedom, competence, control, and even safety, since public transportation options are often thought to be less safe.⁴ Pharmacists can attest, however, to encountering community-dwelling seniors who continue to drive despite being physically limited or cognitively impaired as a result of medications or medical conditions (Table 1 ). For example, polypharmacy, which is a frequent occurrence among seniors, is associated with increased rates of potentially inappropriate medication use and dangerous drug interactions, which in turn are associated with worse physical function and pain in elderly patients.⁵ Many medications commonly used by geriatric patients may cause cognitive and/or visual impairment. In addition, alcohol consumption can alter the body's reaction to medications, thereby altering a variety of functions in the body.⁶ While family members and caregivers may feel relief when an elderly loved one is no longer driving, many seniors may experience mixed emotions, such as a loss of independence and embarrassment, upon relinquishing this privilege.

Physicians play an important role in the safe mobility of their older patients. The American Medical Association encourages physicians to make driver safety a routine part of their geriatric medical services. Other health care professionals who serve seniors, including pharmacists, should educate the public about available resources and programs that assist with this issue. Pharmacists' skills and access to seniors leave them particularly well positioned to broach this subject with these individuals, their families, and their caregivers and to participate in risk assessment.

Driving Skill
In the United States, the possession and renewal of a driver's license by an older individual is regulated by laws that vary from state to state, often differing in areas of renewal intervals (i.e., shorter vs. longer periods), renewal process (i.e., in person vs. via mail or electronic renewal), and requirements (e.g., routine vision and road tests).⁷ Older adults are expected to make appropriate decisions about when to stop driving; however, the hardships imposed on seniors by not driving are not widely recognized.⁸ One study assessed whether not driving is an independent risk factor for entering long-term care institutions. Results indicated that having no other drivers in the house was an independent risk factor for long-term care entry. ⁸ The researchers suggested that innovative strategies aimed at improving existing transportation options for older adults be considered.⁸

Driving is a complicated skill that can be affected by multiple factors, including physical and mental health and the quality of the driving environment, such as road conditions and signage.⁶ Drivers need to be able to visually interpret traffic and road conditions, cognitively recognize images and decide how to react to a situation, and perform the physical movement required to control the vehicle. ⁹ While age alone is not a good indicator of driving skill, changes that take place during the aging process commonly affect sensory perception, cognition, and physical and psychomotor functions, thereby impairing a senior's ability to drive. Medical conditions and medications (Table 1 ) can impair one or more of these functions.⁶ Usually, these changes occur slowly over a prolonged period of time, and a senior is often capable to compensate for minor deficits. If, however, several skill areas are affected, or if there is a sudden change in abilities due to illness or disease, driving skill may become impaired. The Association for Driver Rehabilitation Specialists recommends an evaluation if the driver or the passenger(s) notice any warning signs of impaired driving ability (Table 2 ).

Vision
Driving is a highly visual task, and visual impairments, such as declines in night vision, may occur as early as age 40.⁹

Elderly individuals tend to experience a decline in adequate visual acuity and field of vision due to an increase in the incidence of conditions such as cataract, glaucoma, macular degeneration, and stroke.³ Additionally, impaired contrast sensitivity, glare, and an increase in time to adjust to changes in lightness and darkness are commonly experienced by senior drivers.³ When visual function has been compromised, older adults might place restrictions on their driving (e.g., reducing mileage and avoiding certain high-risk driving situations) in an effort to improve safety.^10,11 One prospective study demonstrated that older adults with worse scores in multiple measures of vision (e.g., acuity, contrast sensitivity, central or lower peripheral visual fields) are more likely to stop driving. ¹⁰ Researchers noted that impairments of contrast sensitivity and visual fields are most associated with driving cessation.¹⁰ Another study found that severe contrast sensitivity impairment due to cataract elevates at-fault crash risk among older drivers, even when present in only one eye.¹²

Cataract is a leading cause of vision impairment in older adults, affecting almost half of those older than 75. One study found that compared with older drivers without cataract, those with cataract were (1) approximately two times more likely to report reductions in number of days driven and destinations per week, a slower driving speed compared with general flow of traffic, and a preference for having someone else drive; (2) five times more likely to have received advice about limiting their driving; (3) four times more likely to report difficulty with challenging driving situations, and thus two times more likely to reduce their driving exposure; and (4) 2.5 times more likely to have a history of at-fault crash involvement in the previous five years.¹³ The researchers concluded that older drivers with cataract experience not only a restriction in their driving mobility but also a decrease in their road safety. ¹³

A reduction in the size of the visual field has been implicated as a major cause of automobile accidents involving drivers of advanced age.¹⁴ Drivers with deficits of peripheral vision have collision rates twice as high as those with normal peripheral visual fields.¹⁵ Age-related reduction in visual acuity in the periphery is attributed to neuron loss in the peripheral retina, presenting with difficulty in driving at twilight due to the peripheral retina's sensitivity to decreased light.

Age-related macular degeneration is the leading cause of severe and irreversible vision loss in the Western world. More specifically, it is the leading cause of vision loss in Americans 60 and older.¹⁵ According to one study, while some seniors with poor vision secondary to age-related maculopathy continue to drive, their driving exposure tends to be low, and they report avoiding challenging on-road situations. Findings suggest that their driving status is related to better eye visual acuity and vision-specific health-related quality of life.¹⁶ More than 50% of the drivers in the study reported that due to their vision, they had difficulty driving or did not drive at all at night, during rush hour or in heavy traffic areas, in the rain, or on freeways or interstate highways.¹⁶

Cognition

Driving requires a variety of high-level cognitive skills, including memory, visual processing, attention, and executive skills.³ Certain medical conditions (e.g., dementia) and medications (e.g,. benzodiazepines, antipsychotics) commonly impact cognition in the elderly (Table 1).^3,17 While individuals with early dementia may be able to continue driving, they can easily become lost or confused in congested traffic.⁷ The ability to make quick decisions and coordinate driving skills may become more difficult as dementia progresses.⁷ These individuals may become unable to interpret visual or auditory sensory input. Patients with dementia reach a point at which it is no longer safe to drive. While some individuals stop driving on their own, others may require intervention (e.g., persuasion, convincing, removal of car keys) to prevent the continuation of driving.

Mobility

Prior to the act of driving, motor abilities are needed to enter the car safely and fasten the seatbelt.³ Muscle strength, endurance, flexibility, and proprioception are examples of motor abilities that are necessary for controlling a vehicle and turning the body to view traffic.³ Age-related changes and musculoskeletal diseases (e.g., arthritis) can decrease an individual's ability to drive comfortably and safely.³ Functional declines render senior drivers vulnerable to crashes in complex situations that require good visual perception, attention, and rapid response. This has resulted in elderly drivers being more likely to experience crashes at intersections, particularly when left-hand turns are involved.³

A stroke can affect the necessary skills for driving independently. The majority of stroke survivors, however, can return to independent driving.¹⁸ To assist with physical problems, adaptive equipment is available, such as a spinner knob (i.e., a device that is attached to the steering wheel to allow controlled steering with the use of one hand) and a left gas pedal (for those unable to use the right foot).¹⁸ To safely use these types of equipment and adapt to new driving methods, training is essential. 

Driver Evaluation and Assistance
Age alone should not determine one's ability to drive. It is capacity, not age, which determines driving fitness.¹⁹ Driving ability, however, is not simple to assess. An evaluation by a driver rehabilitation specialist can be of great value in helping to make the difficult decision as to whether or not a senior should continue driving. A driver evaluation will assess the components of driving that may be compromised in the case of a progressive condition and focuses on the areas of memory, attention, processing speed, visuospatial functioning, decision making, judgment, planning, and behavior. The comprehensive assessment would address factors such as medical and medication history (Table 2) that aid in determining a senior's ability to drive. Following the evaluation, the driver rehabilitation specialist makes specific recommendations regarding driving.

Since it is important to plan for the future, discussing driver ability and safety is recommended while an individual has the insight needed to participate in the decision-making process.²⁰ Therefore, experts recommend that an evaluation be sought when a diagnosis or problems first arise to ensure that compensatory modalities are utilized to help maintain safe driving and to set limits in preparation for discontinuation of driving.²⁰

The Automobile Association of America hosts an informative Web site that is dedicated to helping seniors and their family members cope with the inability to drive and to ensuring that seniors are able to remain active and mobile.²¹ The site addresses the transition to "giving up the keys," supplemental transportation programs, and assistance with locating programs. It also discusses how to use mass transit and options for "Paratransit" for people with disabilities. The American Medical Association, in cooperation with the National Highway Traffic Safety Administration, developed the Physician's Guide to Assessing and Counseling Older Drivers, which includes continuing medical education self-study and evaluation.

Summary

Driving is a complex activity that requires skill and adequate function of vision, cognition, and mobility. Age-related changes in perception, processing abilities, and physical functioning can make driving unsafe. When seniors drive beyond their physical or cognitive ability, public safety is jeopardized. Pharmacists can take an active role in this important public safety issue by assessing the risk of impaired driving ability due to certain medications. Furthermore, due to their accessibility to seniors, pharmacists are well positioned to point out the availability of driver assessment, adaptive devices, and resources that provide education and guidance to seniors and their caregivers.

References

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2. National Center for Injury Prevention and Control. Falls and Hip Fractures Among Older Adults. [fact sheet]. Office of Statistics and Programming. Available at: www.cdc.gov/ncipc/factsheets/falls.htm. Accessed April 11, 2006. 

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9. Kaplan W. The occupation of driving: legal and ethical issues. Physical Disabilities Special Interest Section Quarterly. Bethesda, MD: American Occupational Therapy Association; 1999:22(3):1.

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11. Freeman EE, Munoz B, Turano KA, et al. Measures of visual function and their association with driving modification in older adults. Invest Ophthalmol Vis Sci. 2006 Feb;47(2):514-20.

12. Owsley C, Stalvey BT, Wells J, et al. Visual risk factors for crash involvement in older drivers with cataract. Arch Ophthalmol. 2001;119(6):881-887.

13. Owsley C, Stalvey B, Wells J, et al. Older drivers and cataract: driving habits and crash risk. J Gerontol A Biol Sci Med Sci. 1999;54(4):M203-M211.

14. Zagaria ME. Visual consequences of the aging eye. US Pharmacist. 2002;27(8):33-36.

15. Five Vision Topics Added to NIHSeniorHealth Web Site. National Institutes of Health (NIH). Available at: www.nih.gov/news/pr/jun2005/nia-20.htm. Accessed September 26, 2005.

16. DeCarlo DK, Scilley K, Wells J, et al. Driving habits and health-related quality of life in patients with age-related maculopathy. Optom Vis Sci. 2003;80(3):207-213.

17. Semla TP, Beizer JL, Higbee MD. Geriatric Dosage Handbook. 10th ed. Cleveland: Lexi-Comp, Inc.; 2005:1466-1470.

18. Driving and Stroke. The Association for Driver Rehabilitation Specialists. Available at: www.aded.net/i4a/pages/index.cfm?pageid=310. Accessed November 29, 2006.

19. Fitzpatrick, C. To Drive or Not to Drive. Safe at Home: A Multidiciplinary Approach to Keeping Seniors in the Community. American Society of Consultant Pharmacists 37th Annual Meeting, Phoenix Arizona, November 16, 2006. 

20. Driving and Alzheimer's. The Association for Driver Rehabilitation Specialists. Available at: http://www.aded.net/i4a/pages/index.cfm?pageid=301. Accessed November 29, 2006.

21. For Families and Individuals. American Automobile Association Foundation for Traffic Safety. Available at: www.seniordrivers.org. Accessed November 29, 2006.   

22. Martin S. Common Medications Can Impair Driving. WebMD Medical News. Available at: www.webmd.com/content/article/21/1728_54310. Accessed December 6, 2006.

23. Aging and Driving Fact Sheet. The Association for Driver Rehabilitation Specialists. Available at: www.aded.net/i4a/pages/index.cfm?pageid=1. Accessed November 29, 2006.

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