RT Journal Article SR Electronic T1 Public transit and depression among older adults: using agent-based models to examine plausible impacts of a free bus policy JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 875 OP 881 DO 10.1136/jech-2019-213317 VO 74 IS 11 A1 Yong Yang A1 Brent A Langellier A1 Ivana Stankov A1 Jonathan Purtle A1 Katherine L Nelson A1 Erica Reinhard A1 Frank J Van Lenthe A1 Ana V Diez Roux YR 2020 UL http://jech.bmj.com/content/74/11/875.abstract AB Background Daily transport is associated with mental health. A free bus policy (FBP) may be effective in promoting the use of public transit in older adults and be associated with reductions in depressive symptoms.Methods We developed an agent-based model and grounded it using empirical data from England to examine the impact of an FBP on public transit use and depression among older adults. We also used the model to explore whether the impact of the FBP bus use and depression is modified by the type of income segregation or by simultaneous efforts to improve attitudes towards the bus, to reduce waiting times or to increase the cost of driving via parking fees or fuel price.Results Our model suggests that improving attitudes towards the bus (eg, campaigns that promote bus use) could enhance the effect of the FBP, especially for those in proximity to public transit. Reducing wait times could also significantly magnify FPB impacts, especially in those who live in proximity to public transit. Contrary to expectation, neither fuel costs nor parking fees significantly enhanced the impact of the FBP. The impact of improving attitudes towards the bus and increasing bus frequency was more pronounced in the lower-income groups in an income segregation scenario in which destination and public transit are denser in the city centre.Conclusion Our results suggest that the beneficial mental health effects of an FBP for older adults can be magnified when combined with initiatives that reduce bus waiting times and increased spatial access to transit.