Longitudinal changes in driving behaviours among older adults with different A/T/N biomarker profiles

Abstract

AbstractBackgroundThe pathophysiological process of Alzheimer’s disease (AD) spans approximately 10‐15 years. To define AD by its pathologic processes, the A/T/N classification framework was proposed constituting β‐amyloid (A), tau (T), and neurodegeneration (N) biomarkers derived from cerebrospinal fluid (CSF) or imaging. With these biomarkers, individuals can be divided into four categories: normal (A‐T‐N‐), AD pathologic change (A+T‐N‐), AD (A+T+N‐, A+T‐N+, A+T+N+), and suspected non‐AD pathology (SNAP) (A‐T+N‐, A‐T‐N+, A‐T+N+). Recent evidence indicates that daily driving behaviours can identify preclinical AD, solely based on CSF β‐amyloid (A), with high accuracy. This study aims to determine the extent to which longitudinal changes in driving behaviour vary between individuals with different A/T/N profile categories.MethodParticipants were enrolled in a longitudinal study on driving and preclinical AD biomarkers from Washington University School of Medicine. Temporospatial driving behaviours were collected with a data logger installed in participant vehicles over a period between January 2015 and March 2020. CSF collected within three years of each driving event was used to assign A/T/N categories. The cohort included 132 cognitively normal (Clinical Dementia Rating of 0) older adults (>65). Changes in driving behaviours over time were modelled for each group using linear mixed‐effects models. A Z‐test was used to determine if the slopes significantly differed between individuals with normal biomarkers and the remaining groups.ResultParticipants were classified as 59 individuals with normal biomarkers, 9 with AD pathologic change biomarkers, 45 with AD biomarkers, and 19 with SNAP biomarkers. Compared to normal aging, the AD pathology group had a statistically significantly higher increase in average occurrences of under‐speeding (p = 0.001), a significant decrease in average trip duration (p = 0.021), and a significant decrease in the average standard deviation of vehicle speed (p = 0.029). The AD group had no significant differences from the normally aging group. The SNAP group showed a significantly higher increase in the average occurrences of over‐speeding (p<0.001) than normal aging.ConclusionDriving behaviours and their rate of change over time vary between individuals with different A/T/N profile categories. These differences provide an opportunity to strengthen our understanding of the disease trajectory.