Effects of acute diesel exhaust exposure on brain health: a controlled, blinded crossover study

摘要

Background: Although the effects of prolonged exposure to traffic-related air pollution are well-characterized with respect to respiratory and cardiovascular outcomes, comparatively little is known about the impact of particulate matter on affective, cognitive, and neurodegenerative effects, particularly after short-term exposures.Aims: To establish that acute inhalation of moderate-dose diesel exhaust, typical of occupational or high-ambient concentrations, alters cognitive function in humans through an in vivo, controlled crossover experiment.Methods: We recruited 10 healthy adult subjects and exposed them to two exposure conditions: filtered air and carefully controlled levels of diesel exhaust (300μg PM2.5/m3) for 120 minutes. Prior to and following each blinded condition we measured cognitive outcomes including reaction time, working memory, attention-switching, and executive function tasks using the Cambridge Neuropsychological Test Automated Battery (CANTAB). As well, using functional magnetic resonance imaging (fMRI), we assessed changes in the network of active brain regions attributable to diesel exhaust inhalation and characterized changes in those regions specifically associated with a task of working memory. An array of peripheral blood markers related to neurodegenerative processes were also collected and analyzed at selected time points pre- and post-exposure. Each exposure condition was separated by a 4-week washout period. Repeated measures ANOVA was used to evaluate the main effects of exposure on changes in cognitive endpoints.Results: Preliminary data demonstrates impairment, 1-hour following diesel exhaust exposure, in reaction time (4% [Δ20.3 ms] mean decrease post-DE exposure) and attention-switching (an executive function task). Changes return to baseline over the subsequent 24 hours, post-diesel exhaust exposure.Conclusion: Exposure to acute diesel exhaust exposure may have a deleterious effect on a variety of cognitive endpoints in healthy adult subjects.