Transport disadvantage and dementia: a longitudinal study of trajectories, impacts, and interventions

The National Institute on Aging awarded the University of Memphis $389,999 under the Aging Research program (CFDA 93.866) on September 1, 2026, to conduct a longitudinal study examining how transportation disadvantage affects cognitive decline and dementia risk in older adults.

The study uses data from the National Health and Aging Trends Study, an ongoing nationally representative panel of U.S. Medicare enrollees aged 65 and older, to accomplish three objectives: identify distinct trajectories of transportation disadvantage over time and their determinants; examine the longitudinal relationship between transportation disadvantage and incident dementia, quantifying how much transportation disadvantage contributes to dementia risk; and evaluate how personal transportation choices influence transportation disadvantage and dementia risk through scenario analyses. Transportation disadvantage is defined as unmet transportation needs and inadequate access to transportation due to barriers including distance, cost, physical limitations, or social and environmental factors.

The award period runs through June 30, 2030, with work performed in Memphis, Tennessee.

Abstract

Cognitive decline and maintaining transportation are two linked issues for older adults, and each one affects the other. However, we DON't fully understand how transport disadvantage impact cognitive health. Here transport disadvantage is defined as unmet transport needs and inadequate access to transportation due to barriers such as distance, cost, physical limitations, or social/environmental factors. This study has three aims. First, to understand how transport disadvantages change over time among older adults, identifying distinct trajectories of transport disadvantages and the determinants of these patterns. Second, to examine the longitudinal relationship between transport disadvantages and incident dementia, exploring how much transport disadvantages contribute to incident dementia. The third aim is to evaluate how personal transportation choices may influence transport disadvantages and dementia risk, using various scenario analyses. We will use the national health and aging trends study (nhats), an ongoing longitudinal, nationally representative panel study of U.S. Medicare enrollees aged 65 and older. Among the first to establish transport disadvantages as a modifiable dementia risk, the study will provide critical insights for mitigating transport disadvantages and dementia risk.