The impact of cognitive impairments on driver safety

Cognitive impairment is defined as a decline in one or more of the following domains of cognitive function: perceptual-motor functions (including vision and coordination), language, learning and memory, executive function (such as planning and decision-making), complex attention, and social cognition (like recognition of emotions).[1],[2],[3] The 5th edition of the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM-5) has a new framework for the diagnosis of neurocognitive disorders divided into delirium, mild neurocognitive disorder, and major neurocognitive disorder (dementia).[1],[2] While major neurocognitive disorder corresponds to dementia, the criteria have changed where impairments in learning and memory are not necessary for diagnosis. The diagnostic categories of mild and major neurocognitive disorders mirror one another as a continuum of cognitive impairment and are identified based on severity. In major neurocognitive disorder (dementia) patients show evidence of significant decline in one or more of the cognitive domains, the cognitive deficits interfere with independence in everyday activities and are not explained by delirium or another mental disorder.[1],[2],[3] For more information or more on the changes to the neurocognitive disorders criteria refer to the DSM-5 or the Nature article written by the DSM Neurocognitive Disorders Work Group.[1],[2]

Normal cognitive changes related to aging drivers include: [1],[2],[4]

  • Working memory: decline of ability to retain certain information while simultaneously processing other information.
  • Speed of processing: decrease in speed to organize information into usable patterns and use.
  • Speed of information retrieval: decrease in speed in locating and retrieving previously learned information.
  • Decline in ability to focus on selective attention (important information only) and divided attention (ability to divide attention between multiple stimuli at once).
  • Executive function, insight often involves knowing what action to take in any given situation, such as planning routes, and age is not always a factor. Insight is essential for self-monitoring personal driving ability.

 These domains are evaluated for skills essential in a driving environment.

Cognitive Impairment and Medical Problems

Medical problems can affect the ability of older adults to drive safely. Cognitive impairment, such as dementia, can increase this risk. Medical professionals can screen for risky driving behaviors among older drivers with cognition problems. During an office visit, you can use the following brief tests to determine the level of driving risk before counseling patients and their family members or caregivers about driving tests or other transportation options.

Review Patient's Driving Status
  1. Check-in with family and caregivers about driving history. A clinician can ask a family member or caregiver what they have observed about the patient’s driving skills, including abnormal driving behaviors, such as crashes, dents on the car, difficulty understanding traffic signs, driving too fast or too slow, getting lost in familiar places, and “near misses.”
  2. Review medical history and review of systems. Check for medical conditions that may directly affect cognition, such as Parkinson’s disease, sleep apnea, substance abuse or depression, or a history of falls.
  3. Review medication list. There are medications that may cause cognitive impairment, for example, antidepressants, benzodiazepines, and narcotic analgesics.[5] The American Geriatric Society (AGS) 2019 Beers Criteria update can be useful as a starting point for detecting medications or medication classes to avoid or use with caution for some or all older adults, as many of these medications are relevant to safe driving.[6] In addition, the AAA LongROAD Study identified potentially inappropriate medications (PIMs) most commonly used by older drivers that have been linked to driving impairment and increased crash risk, including benzodiazepines (Diazepam or Valium, typically used to treat anxiety, insomnia, seizures, and to relax the muscles), nonbenzodiazepine, hypnotics, antidepressants, and first-generation antihistamines.[7]
  4. Identify medical conditions that may indirectly affect cognition, such as diabetes, congestive heart failure, cardiac arrhythmia, syncope/orthostatic hypotension, and valvular disease.[5]
Administer Tests to Measure Cognitive Skills

Several screening tools (see Appendix to the Clinician’s Guide, p. 262) measure cognitive skills and can be administered by a clinical team member:[8]

  • Montreal Cognitive Assessment (MoCA) detects mild cognitive impairment and is available in multiple languages. MoCA takes only 10-15 minutes to administer.
  • Trails B assesses working memory, visual processing, visuospatial skills, selected and divided attention, and psychomotor coordination. Poor performance on this test is associated with poor driving performance.
  • Clock drawing assesses long-term memory, short-term memory, visual perception, visuospatial skills, selective attention, abstract thinking, and executive functioning.
  • Maze assesses visual perception, visuospatial skills, abstract thinking, and executive skills. The Snellgrove Maze, a one-page cognitive screen for driving competence, was validated with older adults with mild cognitive impairment or early dementia.

Poor performance on these tests correlates with poor driving outcomes in older adults with dementia, including increased crash rates and impaired performance in driving simulations and on-the-road tests.

Assess Level of Major Neurocognitive Disorder (Dementia)

Medical professionals tend to base their decisions about safe driving on the severity of neurocognitive disorder rather than on the presence of neurocognitive disorder or dementia itself. The Clinical Dementia Rating (CDR) is an evidence-based tool that can be used to assess the level of major neurocognitive disorder (dementia) of the patient. In addition, the Alzheimer’s Association assists families with education and counseling about driving issues.

Next Steps for Medical Professionals

Identify any medical conditions and medications causing increased risk of cognitive impairment; treat or reduce medical risks and/or refer for additional evaluation and treatment from clinical specialists. Below are some suggestions for next steps depending on the findings of your examination of the individual.

  • Referral: If driving deficits continue to exist after medical conditions have been treated, refer the older driver to
    • an occupational therapist for assessment of functional abilities and mobility support
    • a driving rehabilitation specialist for further evaluation and treatment
    • a social worker for assessment of transportation needs, caregiver support, and training recommendations
  • Resources: Provide patients and caregivers with information and referrals to local and national resources that support continued older adult mobility, such as the National Highway Traffic Safety Administration and others listed on page 176 of the Clinician’s Guide.[9]
  • Restriction: For the older adult with persistent driving deficits, recommend restricted driving, cessation of driving until further recovery, or permanent license restriction if recovery is unlikely. Review your state’s licensing and license renewal criteria and any mandates for healthcare professionals to report unsafe drivers or those with specific medical conditions. A database of driver licensing policies and practices can be found at 

[1] American Psychiatric Association. (2022). Neurocognitive disorders. In Diagnostic and statistical manual of mental disorders (5th ed., text rev.).

[2] Sachdev, P. S., Blacker, D., Blazer, D. G., Ganguli, M., Jeste, D. V., Paulsen, J. S., & Petersen, R. C. (2014). Classifying neurocognitive disorders: the DSM-5 approach. Nature Reviews Neurology10(11), 634–642.

[3] Hugo, J., & Ganguli, M. (2014). Dementia and cognitive impairment: epidemiology, diagnosis, and treatment. Clinics in Geriatric Medicine30(3), 421–442.

[4] Karthaus, M., & Falkenstein, M. (2016). Functional Changes and Driving Performance in Older Drivers: Assessment and Interventions. Geriatrics1(2), 12.

[5] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition). The American Geriatrics Society.

[6] 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.

[7] Andrews, H.F., Betz, M.E., Chihuri, S., DiGuiseppi, C., Eby, D.W., Gordon, A., Hill, L.L., Jones, V.C., Lang, B.H., Leu, C.S., Li, G., Merle, D.P., Mielenz, T.J., Molnar, L.J. & Strogatz, D.S. (2018). Prevalence of Potentially Inappropriate Medication Use in Older Drivers: AAA LongROAD Study (Research Brief). AAA Foundation for Traffic Safety.

[8] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.262). The American Geriatrics Society.

[9] Pomidor, A. (2019). Clinician’s guide to assessing and counseling older drivers (4th edition, pp.176). The American Geriatrics Society.