Cognitive Challenges

Driving is a complex activity that requires a variety of high-level cognitive skills, including memory, visual processing, attention, and decision making. Dementia and side effects from a variety of medications commonly used by older adults, such as pain medications used for arthritis,³⁹ can affect cognition and increase crash risk.⁴⁰

Memory

Older adults become more easily distracted and therefore find difficulty paying attention to incoming information and storing it appropriately.⁴¹

Aging also slows the ability to retrieve memories. When driving, this affects both their ability to quickly interpret the distance to oncoming traffic and their response time.⁴²

Attention

Attention-switching

Drivers must quickly transfer attention from one traffic situation to another. Attention switching requires rapidly processing a number of events while paying attention to steering a course. Vision, hearing or cognitive impairments can influence attention switching.⁴³

Divided Attention ("Multitasking")

Older drivers can experience more difficulty in dividing their attention among multiple tasks and in switching rapidly from one task to another. Difficulty in switching rapidly from one task to another makes using cellular phones or navigation systems, tuning the radio or even listening to conversations among passengers disruptive to driving concentration.⁴⁴

Completion of Missing Information

Drivers continually fill in missing information from cues around them. Fast-moving traffic, diminished visibility or missing traffic signs may give only partial information that drivers must complete. With cognitive slowing, the ability to fill in missing information correctly diminishes, putting the driver at risk by forcing a dangerously slow speed on the road, and causing confusion and disorientation at traffic detours or significant turns.

Dementia

Older adults who do not suffer from dementia are often able to assess their driving and make appropriate changes in driving behavior without help from family, partner or professionals. Dementia affects cognitive functions critical to driving such as judgment, reaction time and problem-solving abilities, and causes physical and sensory problems that increase driving risk.⁴⁵

Once a doctor diagnoses dementia, the question is not "if" a person should stop driving, but rather "when." In Alzheimer's disease, early and clear warning signs that indicate the disease is affecting driving can include:

• Needing more help than in the past with directions or learning a new driving route
• Trouble remembering the destination of the trip or locating one's parked car
• Getting lost in familiar places
• Trouble making turns, especially left turns
• Feeling confused when exiting a highway or by traffic signs such as a four-way stop
• Stopping at green lights or braking inappropriately
• Drifting out of one's road lane
• Causing damage to one's car without the ability to explain what happened
• Finding others questioning driving safety
• Difficulty controlling anger, sadness or other emotions while driving

Dementia occurs when there is a progressive loss of cognitive function. It is characterized by impairments in memory, abstract thinking, and judgment. Dementia sufferers are less able to recognize their limitations as drivers and make adjustments to their driving accordingly.⁴⁶

A dementia diagnosis should not be the sole basis for the decision to revoke an older adult's license. Some demented drivers are able to function safely by driving only in areas they are familiar with. The severity of the dementia should be considered before recommending that a driver's license be revoked.⁴⁷

In addition to dementia, other conditions may result in similar types of cognitive impairment, including stroke, Parkinson's disease, diabetes, cardiovascular damage, and the side effects of medications^48,49 or alcohol. In some of these cases, a change in medications or dosage may be sufficient to restore memory and attention functions.

Conditions Affecting Cognition and Driving⁵⁰

Condition	Effect on Driving	Risk of Developing Condition with Aging	Crash Risk (Summary of Research Findings)
Dementia51	Disorientation, resulting in driving at dangerously slow speeds, inappropriate turns or stopping Loss of internal "map" and points of reference, possibly causing weaving in traffic lanes, disorientation, and getting lost in familiar places Perception of own driving ability that usually does not match others' perceptions or the actual driving performance	11.6 percent for those ages 65-84 47.8 percent for those ages 85+	Up to 3-4 times higher than older adults with no cognitive impairment
Medications52	Possible effects of: Antidepressants, antihistamines, and benzodiazepenes: blurred vision (affecting how the driver sees traffic), drowsiness (affecting driving response) and motor coordination (affecting the physical response to traffic situations) High blood pressure: impaired response due to dizziness and fatigue. Beta blockers may cause confusion and insomnia (resulting in poor driving response time or falling asleep at the wheel) Pain killers (even some nonsteroidal anti-inflammatory drugs (NSAID): confusion, causing dangerously slowed driving, and poor response time to traffic situations. Muscle relaxants and narcotics increase this effect.	Increased crash risk shown by drivers who take tricyclic antidepressant

³⁹ Carr, "The older adult driver."

⁴⁰ AMA, "Why are older drivers at risk?"

⁴¹ NHTSA, "Attention." Older Road User Research Plan.

⁴² Ibid.

⁴³ Ibid.

⁴⁴ Meyer and Coughlin, p. 3.

⁴⁵ The Hartford (2000) "Why Dementia and Driving Is a Difficult Issue." Retrieved from The Hartford on the World Wide Web: www.thehartford.com/alzheimers/why_dementia.html.

⁴⁶ NHTSA, "Attention."

⁴⁷ Ibid.

⁴⁸ Ibid.

⁴⁹ Ibid.

⁵⁰ NHTSA, Safe Mobility for Older People Notebook.

⁵¹ MEDLINEplus. Medical Encyclopedia "Dementia." Retrieved from National Library of Medicine on the World Wide Web: www.nlm.nih.gov/medlineplus/ency/article/000739.htm.

⁵² American Medical Association (2003) Physician's Guide to Assessing and Counseling Older Drivers. Retrieved from AMA on the World Wide Web: www.ama-assn.org/ama/pub/category/10791.html.