(See also Overview of the Older Driver.)
Older adults are likely to have multiple comorbidities and may be taking several drugs. A significant number of drugs, typically those affecting the central nervous system (eg, causing confusion, sedation) can potentially impair driving. Many have been shown to impair actual driving in road tests, driving simulators, and have been associated with an increase in motor vehicle crash (MVC) risk. Despite these risks, many of these drugs should not be stopped abruptly and may need to be tapered. Obtaining input from the prescribing physician or pharmacist is important before discontinuing them.
Drugs that have been shown to increase driving risk include
Antihistamines, benzodiazepines, opioids, anticholinergics, hypnotics, antihypertensives, and tricyclic antidepressants, which can cause drowsiness, hypotension, or arrhythmias
Antiparkinsonian dopamine agonists (eg, pergolide, pramipexole, ropinirole), which can occasionally cause acute sleep attacks
Antiemetics (eg, prochlorperazine) and muscle relaxants (eg, cyclobenzaprine), which can alter sensory perception
Antiseizure drugs, which can cause sedation (alternatives may need to be considered)
When starting a new drug that could affect visual, physical, or cognitive function, patients should refrain from driving for several days (depending on the time required to reach a steady state) to be sure no adverse effects occur.
Falls and MVCs share common causative factors (eg, impaired vision, muscle strength, cognition). A history of falls in the past indicates increased risk of MVCs in older adults and should prompt further evaluation for intrinsic factors that can impair mobility and driving (eg, visual, cognitive, motor skills). (See Functional Assessment of the Older Driver.)
The presence of a cardiac disorder may increase driving risk, particularly disorders that may impair consciousness or cause syncope (eg, arrhythmias). Patients who have had cardiac procedures (eg, coronary artery stents or bypass grafts, placement of internal defibrillator/pacemakers) or certain acute events (eg, unstable angina, myocardial infarction) need to refrain from driving for a brief time during recovery; the length of time depends on the procedure and the patient's clinical condition. Clinicians should consult national guidelines and resources (National Highway Traffic Safety Administration's Clinician's Guide to Assessing and Counseling Older Drivers, 4th edition). Cardiac disorders can cause chronic cognitive impairment (eg, sedation, drowsy driving) or acute impairment in consciousness (eg, dizziness, syncope).
Patients with severe heart failure (eg, class IV heart failure, dyspnea at rest or while driving) should refrain from driving until they can be evaluated with on-road testing and have the approval of their clinicians.
Neurologic disorders also increase driving risk. Specific disorders include
Stroke or transient ischemic attack (TIA): Drivers with a single TIA should wait 1 month before resuming driving; those with recurrent TIAs or a stroke should be event-free for at least 3 to 6 months before resuming driving and be cleared by their neurologist or primary care physician. Physical examination should be done to assess how residual disability due to stroke may affect driving ability. Consider referring those with persistent visual, motor, or cognitive deficits to an occupational therapist-based driving assessment clinic.
Seizures: Regulations for drivers who have seizures are state-specific, but most states require a seizure-free interval (often 6 months) before they reinstate driving privileges. Antiseizure drugs can adequately control seizures in about 70% of patients, although relapses may occur when these drugs are withdrawn. State-specific information regarding driver's license eligibility for people who have seizures should be sought along with advice from a neurologist (see also Epilepsy Foundation State Driving Laws Database).
Alzheimer disease or progressive dementing disorders will eventually impair key functional abilities, including those required for driving. Monitoring patients for new driving errors that can be attributed to changes in cognition or identifying significant impairments in psychometric tests may be useful in determining referrals for on-road evaluation and/or possibly driving cessation. Several states presently require physicians to report significant cognitive impairment to the state's Department of Motor Vehicles.
Many other neurologic disorders (eg, Parkinson disease, multiple sclerosis) cause disability and should be monitored by functional assessment and, when appropriate, an on-road evaluation.
Diabetes mellitus poses a risk because patients may become hypoglycemic while driving. Patients who have had a recent hypoglycemic episode with unawareness should not drive for 3 months or until factors contributing to the episode (eg, diet, activity, timing and dose of insulin or antihyperglycemic drug) have been assessed and managed. Sensory changes in the extremities due to neuropathy, retinopathy, or both caused by diabetes can also impair driving ability.
Severe hyperglycemia is associated with cognitive impairment, and patients should not drive until their blood glucose and symptoms are under better control.
Sleep disorders, most notably obstructive sleep apnea syndrome, can cause drowsiness leading to MVCs, and patients should refrain from driving until they are adequately treated. Use of a continuous positive airway pressure (CPAP) device has been shown to improve performance in a driving simulator and reduce MVCs.
United Kingdom Driving & Dementia Working Group (2018). Driving with dementia or mild cognitive impairment: Consensus guidelines for clinicians.