When do problems with memory and decision-making affect older adults' ability to drive?

Car crashes can be devastating or even deadly for anyone, including older adults and other road users. However, the fatal crash rate based on the distance someone travels in a vehicle begins to rise at age 65. At the same time, when older adults stop driving due to health issues or other concerns, they may experience isolation and depression. They also may be more likely to enter long-term care facilities earlier than they otherwise would.

Researchers have a history of studying driver safety in older adults after they've been diagnosed with dementia, a decline in memory and other mental abilities that make daily living difficult. However, we have limited knowledge about the effects on older drivers whose problems with mental abilities are less severe than those associated with dementia.

Recently, a team of researchers designed a study to learn more about cognitive health and older drivers' crash risks. The study was published in the Journal of the American Geriatrics Society. In this study, the researchers focused on links between levels of cognitive function and crash risk among older drivers without dementia over a 14-year study period. They also assessed the link between changes in cognitive function over time and later risks of crashes.

The researchers used information from the Adult Changes in Thought (ACT) study, an ongoing study of adults aged 65 and older. The researchers linked ACT data from 2002 to 2015 to the Washington State crash database and to information from the Washington State Department of Licensing.

ACT participants were tested for their ability to think and make decisions. Researchers followed 2,615 participants for an average of 6.7 years or until they dropped out of ACT, died, were diagnosed with dementia, or failed to renew their license. The researchers then looked at motor vehicle crashes involving ACT participants. They included all crashes resulting in injury, death, or property damage totaling at least $1,000.

For older licensed drivers without dementia, lower levels of cognitive function were linked to a higher risk of motor vehicle crashes. Depression also was linked to a higher risk for crashes in older licensed drivers without dementia.

The researchers noted that, unfortunately, there is not yet a widely accepted specific clinical exam, procedure, or lab test that can evaluate driving and crash risk related to cognitive function. The researchers concluded that older drivers with lower levels of cognitive function were somewhat more likely to be involved in a crash. These older drivers, their family members, and their healthcare providers must balance the benefits of independence, mobility, and social engagement with the potential for car crashes as they make decisions about whether an older person should continue to drive.