By Ingrid Fadelli
Credit: Unsplash.com, Neda Vidakovic.
Driving is a complex skill that involves a wide range of mental processes and abilities. Drivers need to pay close attention to what is happening around them, remember the meaning of road signs, respond quickly to unexpected situations and make decisions that often involve the safety of others.
Some cognitive abilities, including memory and processing speed, tend to decline with age, although the extent of these changes varies considerably among individuals. People with tau pathology, the abnormal accumulation of a protein called tau inside brain cells, often experience more pronounced cognitive difficulties. Tau pathology is associated with Alzheimer's disease (AD) and other conditions characterized by the progressive damage or loss of nerve cells.
Mental health disorders can also affect cognitive functioning. For instance, people with major depressive disorder (MDD), a psychiatric condition characterized by persistent low mood or loss of interest in everyday activities, can experience difficulties with concentration, memory, decision-making and planning.
Both memory problems and other cognitive difficulties can affect people's ability to complete everyday tasks, including driving. However, little is known about how MDD and biological signs of Alzheimer's disease might jointly influence changes in the driving behavior of older adults.
Researchers at Washington University School of Medicine and Adelphi University recently investigated whether MDD and biological markers of Alzheimer's disease (AD) are associated with changes in the driving patterns of older adults. Their findings, published in Molecular Psychiatry, suggest that the driving behaviors of older adults with both MDD and tau pathology could become riskier more quickly than those of healthy older adults without these conditions.
"Driving is a complex task that can be compromised by mood disorders and neurodegenerative conditions," wrote Yiqi Zhu, David C. Brown and their colleagues in their paper. "MDD and AD increase in prevalence with older age. Preclinical AD, identified through protein biomarkers, is strongly associated with an increased risk of developing AD."
Monitoring how older adults drive for over four years
Zhu, Brown and their colleagues recruited 269 adults ages 65 and older, 61 of whom had been diagnosed with MDD. Using brain scans collected with an imaging technique called positron emission tomography (PET), they identified participants who exhibited an abnormal accumulation of amyloid or tau. Notably, the abnormal accumulations of amyloid and tau are known biological markers of AD and some other neurodegenerative conditions.
The researchers installed devices in the study participants' vehicles that recorded vehicle movements and GPS data. Participants also carried Bluetooth beacons, small wireless devices that transmitted identifying signals to the system in the car, helping researchers confirm that the participant was present during each recorded journey.
The team monitored the older adults' driving for an average of four and a half years. They then analyzed the collected data to calculate the number of journeys participants made, their maximum travel distance, incidents of hard braking and hard cornering, sudden acceleration, speeding, the number of unique destinations visited, the geographical area covered and the predictability of travel patterns.
"This study tracked the daily driving behaviors of older adults over an average period of 54 months and found participants with MDD and PET biomarker tau had a faster increase in risky driving behaviors, such as hard braking, and a slower decline in randomness of driving patterns, compared to healthy controls," wrote the authors. "Notably, participants with MDD were more likely to exhibit PET tau positivity than PET
amyloid positivity, suggesting a potential interaction between MDD and tau pathology."
How these findings could inform monitoring and interventions
The researchers found that participants with both MDD and tau positivity showed a faster increase in some risky driving behaviors over time. Specifically, they exhibited a faster increase in hard braking than older adults with no known diagnoses and a faster increase in hard cornering than participants with MDD alone.
Their driving patterns also remained comparatively unpredictable over time. However, participants with MDD alone did not exhibit significantly more risky driving behaviors than healthy participants.
Participants with Alzheimer's biomarkers but without MDD, on the other hand, were found to sometimes display more cautious driving patterns. The findings therefore hint at a possible combined association between MDD, tau pathology and certain changes in driving, rather than a general decline caused independently by either condition.
"These findings highlight the importance of monitoring older drivers for emerging functional vulnerability associated with mood disorders and neurodegeneration at an early stage," wrote Zhu, Brown and their colleagues.
In the future, the study could inform research into tools for identifying subtle changes in the everyday functioning of older adults. If the team's findings are confirmed in future studies, long-term driving data might eventually complement clinical evaluations and formal driving assessments, helping professionals identify people who could benefit from additional support or monitoring.
More information: Yiqi Zhu et al, Tau pathology and depression interact to accelerate driving decline in cognitively normal older adults, Molecular Psychiatry (2026). DOI: 10.1038/s41380-026-03761-7.
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