Assessing functional abilities for driving

You can take advantage of the comprehensive Clinical Assessment of Driving Related Skills (CADReS), a toolbox of evidence-based, practical, office-based assessment tools to screen for impairment in the key areas of vision, cognition, and motor/sensory function as they relate to driving. isthe This comprehensive toolbox is available in the Clinician’s Guide to Assessing and Counseling Older Drivers, 4th Edition, published by the American Geriatric Society (referred to as the Clinician’s Guide, Chapter 3, p. 28-47).[1] The following provides a step-by-step approach summarizing how you can integrate safe driving into ongoing office visits and patient encounters.

Step 1: Interview and Driving History

You can assess whether older adults are functionally able to continue safe driving using the Modified Driving Habits Questionnaire (MDHQ), a shorter version of the original Driving Habits Questionnaire (DHQ). The MDHQ comprises 30 questions and focuses on current driving history, accidents, citations, driving space, and other factors for detecting driving habits in the elderly population. (Soon). Both the patient and caregiver can answer questions about current driving practices. The modified version is available in Appendix C of the Clinician’s Guide, p. 228.[2]

You can also ask the patient about activities of daily living (ADLs) and Instrumental activities of daily living (IADLs). ADLs are basic tasks such as feeding, dressing, grooming, and bathing. IADLs are more complex tasks that include driving, using public transportation, financial management, housekeeping, and using the telephone. Medical professionals would ask: “Do you have difficulty or require assistance with any of the following?” A checklist of both types of activities and scoring guidelines are available from the National Library of Medicine: Activities of Daily Living.

Age-related declines may lead to the deterioration of either ADLs or IADLs. Driving uses the same underlying functions (such as visual processing, executive functioning, memory, and processing speed) as other IADLs, and any restrictions in IADLs may warrant further driving evaluation.

Step 2: Vision Screening

Driving demands strong visual acuity and skills. At the same time, vision is the most relevant age-related impairment for driving. Approximately 80 to 90 percent of information related to traffic is received visually. Visual factors, along with cognition, explain 83 to 95 percent of “age-related variance in the capacity to drive safely”.[3]

General visual acuity commonly declines with age due to increased eye changes and incidences of conditions such as cataracts, glaucoma, diabetic retinopathy, and age-related macular degeneration (ARMD). These conditions can be easily measured in office settings using tools such as the Snellen chart. Near visual acuity also can be measured by the Rosenbaum pocket chart or other methods to confirm the following:

  1. Visual Field is measured by confrontation testing (having the patient look directly at the clinician’s eye or nose to test each quadrant in a patient’s visual field and having them count the number of fingers shown). Each eye should be tested separately. If deficits are noted, formal visual field perimetry may be indicated, which may require referral to an ophthalmologist. Most problems related to visual field are the result of glaucoma, detached retina, and stroke. Loss of peripheral vision may cause problems in noticing traffic signs or cars, vehicles in adjacent lanes, or street crossings.4 
  2. Contrast sensitivity, measured by the Pelli Robson contrast sensitivity chart, decreases with aging and is often an issue during dawn and dusk hours, in foggy conditions, or during storms.5 A driver should be able to recognize objects at reasonable distances in a short time. Many studies show contrast sensitivity can help predict a driver’s ability to see an oncoming target or stationary object at the first possible moment.
  3. Cataracts are another major concern associated with vision and driving because their gradual development results in a slow change in vision that the older adult may not recognize. Cataract removal can effectively improve driving safety.
Step 3: Cognition Evaluation

Driving requires timely cognitive and visual processing to make appropriate decisions in a complex environment. Therefore, these skills are vital for safe driving. Cognition changes can decrease functions needed to solve problems and cope with challenging traffic situations.

Dementia deserves special emphasis because it presents a significant challenge to driving safety. As the disease progresses, individuals will lose the ability to drive safely. In addition, older adults with dementia often lack insight into their deficits. Therefore, older drivers with dementia may be more likely than drivers with visual or motor deficits (who tend to self-restrict their driving to accommodate their declining abilities) to drive even when it is unsafe. In this case, it becomes the responsibility of family members and other caregivers to protect the safety of older adult drivers with dementia by enforcing driving cessation when necessary.

The Dementia Screening Interview is an eight-item caregiver questionnaire that differentiates between dementia and normal aging. Preliminary data indicate that the interview can be used with other tools to decide whether an aging adult is fit to drive.

The Impact of Cognitive Impairments on Driver Safety provides more detailed information about cognitive skills assessment in older drivers and offers resources that address dementia. This fact sheet, available in the Appendix of the Clinician's Guide, pp. 233-238, describes tests for measuring cognition.[6] These screening tools include the Montreal Cognitive Assessment, the Trail-Making Tests A/B, the Snellgrove Maze test, and the clock-drawing test, all of which assess visuospatial ability, executive function, attention and psychomotor coordination, memory, and insight into one’s own driving abilities.

You may choose to take one or more of the following steps after conducting the in-office tests:

  • Review the older adult’s medications and assess for potential adverse effects of the medications on cognition.
  • Ask the older adult and caregivers about the onset of cognitive decline relative to new medications or changes in dosage.
  • Treat the underlying disorder and/or adjust medications. Refer the older adult for more extensive examination to a neurologist, psychiatrist, or neuropsychologist.
  • Recommend a comprehensive driving evaluation by a driving rehabilitation specialist to assess the older adult’s performance in the actual driving task. An initial, comprehensive on-road assessment with retesting at regular intervals is particularly useful for those with progressive dementing illnesses.
Step 4: Motor/Sensory Function Assessment

Aging causes decreases in muscle strength, reaction time, and mobility (particularly of the neck, shoulder, and wrists)—all of which can affect driving ability in addition to increasing the risk of falls and other complications. These declines restrict the field of view in traffic or the ability to control the steering wheel. Tasks such as fastening a seatbelt or modulating the pressure needed on the brake pedal may be impossible for some aging adults to complete if they lack motor and somatosensory abilities.

In an office setting, you can conduct three simple tests that measure overall lower extremity strength, coordination, and proprioception in a function task.

  • Rapid Pace Walk test measures ambulatory function, measures lower limb strength, endurance, and balance. The patient walks 10 feet and returns, using their normal assistive gait device, if necessary. Those adults requiring more than nine seconds are considered at increased risk for motor vehicle crashes. The clinician can review the causes of the slower pace and consider interventions, such as physical therapy.
  • Get Up and Go, a complementary test to Rapid Pace Walk that evaluates balance and gait, requires patients to stand up from a chair, walk 10 feet, turn around, return, and sit down again. The clinician can detect hesitancy, slowness, staggering, stumbling, and other abnormal movements of the trunk and upper and lower extremities. If a patient takes 12 seconds or longer to walk the distance, this may indicate a need for referral and treatment.[7] The results of the test conducted in conjunction with other assessments may be linked with a higher risk of falls, which are also a marker for poor driving outcomes.[8],[9]
  • Functional Strength and Range of Motion can be tested in-office, with the clinician asking the patient to perform the motions listed below bilaterally:
    • Neck rotation: “Look over your shoulder like you’re backing up or parking. Now do the same thing for the other side.”
    • Shoulder and elbow flexion: “Pretend you’re holding a steering wheel. Now pretend to make a wide right turn, then a wide left turn.”
    • Finger curl: “Make a fist with both of your hands.”
    • Ankle plantar flexion: “Pretend you’re stepping on the gas pedal. Now do the same for the other foot.”
    • Ankle dorsiflexion: “Point your toes toward your head.”

A clinician scores this test by evaluating the motion as either “within functional limits” or “not within functional limits.” The latter score indicates that range of motion is done with excessive hesitation, pain, or a very limited range of motion.[10]

A more comprehensive driver’s skills assessment of motor abilities is available from the University of Missouri Geriatric Toolkit.

After reviewing the results of the tests to measure motor skills, you may offer the following recommendations, along with required prescriptions and any restrictions:

  1. Begin or maintain a physical activity program, with a physician’s approval, that includes cardiovascular exercise, strengthening exercise, stretching, and balance exercises. Activities and information for older adults can be downloaded at the National Institutes of Health (NIH) Institute on Aging website.
  2. Make an appointment with a physical or occupational therapist to improve strength, flexibility, and range of motion.
  3. Learn about vehicle adaptation, such as hand controls, bigger mirrors, or adjustable foot pedals, that may compensate for a limited range of motion or other physical deficits that limit driving safety. Refer patients to ChORUS for additional information on vehicle safety features and adaptation and to CarFit, an educational program that allows older drivers to check how well their current vehicle “fits” them.
  4. Contact a local driving rehabilitation specialist (DRS) to provide a comprehensive assessment, help determine a driver’s medical fitness to drive, and recommend training or vehicle adaptations to assist drivers. Medical professionals may be able to locate a DRS through the Nationwide Database of Driving Evaluation Specialists, developed by the American Occupational Therapy Association (AOTA).
Step 5: Review of Medications

Older adults often take multiple medications concurrently, with approximately 36 percent using five or more prescription medications. In addition, older adults often take multiple central nervous system (CNS)-active medications, with 25 percent taking two or more classes of medication. A major cause of motor vehicle accidents and crashes that result in injury and fatality is impaired driving, which can be due to certain classes of medication. Medications associated with increased crash risk are referred to as potential driving-impaired (PDI) medications. These medications include those that impact the CNS, blood glucose levels, blood pressure, vision, or that pose risks to safe driving (for example, by affecting a driver’s cognition, judgment, and reaction time). Often, patients who take over-the-counter or prescription medications are not aware of the negative impact these medications can have on safe driving.

The most common PDI medications are:[11]

  • Anticholinergics
  • Anticonvulsant
  • Antidepressants
  • Antiemetics
  • Antihistamines
  • Antiparkinsonian agents
  • Antipsychotics
  • Benzodiazepines and nonbenzodiazepine hypnotics
  • Muscle relaxants
  • Narcotic analgesics

The Clinician’s Guide summarizes the common PDI medications and the adverse effects (cognitive, visual, and motor abilities) that may contribute to impaired driving.[4] For more detailed information about each class of medications, download a PowerPoint presentation and additional text provided by a medical expert.[12]

PDI effects include:

  • Sedation or drowsiness
  • Hypoglycemia
  • Blurred vision
  • Hypotension
  • Dizziness Fainting Mood changes
  • Loss of coordination (ataxia)[12],[13] Other substances, including alcohol, marijuana, cocaine, and amphetamines, also cause impaired driving, which can increase the risk of crashes. Marijuana use, for example, has increased among older drivers and a combination of the cognitive change and sedation effects can have harmful consequences for older drivers.[14]

Another resource that can be used as a starting point in reviewing an older patient’s medications is the American Geriatric Society (AGS) 2019 Beers Criteria © Update of Potentially Inappropriate Medication Use (PIMS).[15]

The 2019 AGS Beers Criteria® includes 30 individual criteria of medications or medication classes to be avoided in older adults and 16 criteria specific to more than 40 medications or medication classes that should be used with caution or avoided in certain diseases or conditions. These criteria are a valuable tool and can be part of a comprehensive approach to medication use in older adults. Used in conjunction with other tools and management strategies for improving medication safety and effectiveness, the criteria can be a relevant resource to ensure safe driving for older adults.

Medical professionals can take the following steps to ensure safe driving among patients who are taking medications, particularly PIMS:

  • Consider the risks and benefits of all medications taken by a patient in terms of driver safety, taking into consideration the patient’s existing regimen of prescription and non-prescription drugs.
  • Try to prescribe non-impairing medications and the safest drug/medication class when possible.
  • Introduce new medications at the lowest dosages; modify any changes in dosage with recommendations to the patient to refrain from driving until the patient believes that no adverse events will occur.
  • If medications are introduced while the older adult is hospitalized, adverse effects on driving performance should be discussed before discharge.
  • Document discussions with the patient/caregiver in the medical record about potential risks to driving safety. This is particularly important because clinicians, who have a duty to warn, can be held accountable for medication adverse effects on patients while driving.12

Another physician resource is Medscape’s Driver Safety Clinician’s Connection site. This site hosts CME/CE-associated learning activities to facilitate the clinicians’ ability to assess patient-driving challenges and risks. Activities include driving safety discussions with potentially at-risk drivers (those older and/or drug-impaired) and their families. Strategies are provided to enable clinicians to modify risk when appropriate and to address what to do if your patient is a potential safety risk to themselves and others because they continue to drive. To obtain credit, you first should register on Medscape and then take the free courses at Driver Safety: The Clinician’s Connection.

[1] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.28-47). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[2] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.228). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[3] Dattoma L. L. (2017). Evaluation of the older driver. Primary Care, 44(3), 457–467. https://pubmed.ncbi.nlm.nih.gov/28797372/

[4] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[5] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.50). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[6] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp. 233-238). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[7] Centers for Disease Control and Prevention. (2017). Assessment: Timed up and go (TUG). Retrieved March 27, 2023 from https://www.cdc.gov/steadi/pdf/TUG_test-print.pdf

[8] Barry, E., Galvin, R., Keogh, C., Horgan, F., & Fahey, T. (2014). Is the Timed Up and Go test a useful predictor of risk of falls in community dwelling older adults: a systematic review and meta-analysis. BMC Geriatrics, 14, 14. https://pubmed.ncbi.nlm.nih.gov/24484314/

[9] Scott, K.A., Rogers, E., Betz, M.E., Hoffecker, L., Li, G., & DiGuiseppi, C. (2016). Associations between falls and driving outcomes in older adults: A systematic review and meta-analysis: A LongROAD Study. AAA Foundation for Traffic Safety. https://aaafoundation.org/wp-content/uploads/2017/12/SeniorsAndFalls.pdf

[10] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.43). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[11] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.146). The American Geriatrics Society. https://geriatricscareonline.org/ProductAbstract/clinicians-guide-to-assessing-and-counseling-older-drivers-4th-edition/B047

[12] Marottoli, R. (2017). Medication risks for older drivers [Continuing Education Lecture, PowerPoint slides]. Medscape Education. https://www.medscape.org/viewarticle/876904_2

[13] Lococo, K. H. & Tyree, R. (2010). Module 5: Pharmacists' roles and responsibilities in counseling patients regarding medications and driving risk. Medscape Education. Retrieved March 27, 2023 from https://www.medscape.org/viewarticle/725023.

[14] Choi, N. G., DiNitto, D. M., & Marti, C. N. (2016). Risk Factors for Self-reported Driving Under the Influence of Alcohol and/or Illicit Drugs Among Older Adults. The Gerontologist, 56(2), 282–291. https://pubmed.ncbi.nlm.nih.gov/25063352/

[15] By the 2019 American Geriatrics Society Beers Criteria® Update Expert Panel (2019). American Geriatrics Society 2019 Updated AGS Beers Criteria® for Potentially Inappropriate Medication Use in Older Adults. Journal of the American Geriatrics Society, 67(4), 674–694.