BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) SERUM LEVELS POST EXPOSURE TO TRAFFIC RELATED AIR POLLUTION AND INTERDEPENDENCIES WITH PHYSICAL ACTIVITY

Abstract

Background: BDNF is assumed to improve cognitive function. Traffic related air pollution has been shown to reduce the exercise induced BDNF release. Aims:We aimed to study the BDNF levels in a healthy population in Barcelona following short term exposures to traffic air pollution under real world conditions and the role of moderate physical activity as a potential effect modifier. Methods: Well controlled crossover study design comparing serum BDNF levels pre- and 40 minutes post-exposure to traffic related air pollution. Thirty-one healthy non-smoking subjects were exposed for 2 hours to contrasting pollution levels while either cycling or resting. Each volunteer was to undergo all four conditions (high vs. low exposure; moderate physical activity vs. resting). On-site exposure monitoring included particulate matters, nitric oxides (NOx), and elemental carbon (EC). Results: Concentrations of ultrafine particles, EC, and NOx levels at the high exposure site on average 5, 7, and 10 times higher than the low exposure site, respectively. 28 volunteers completed all 4 exposure combinations (53,6% females; mean age 34,4 years). Mean BDNF comparisons showed a decrease from baseline in cycling subjects (-10.7% in low air pollution vs. -4.3% in high) compared with those in rest (0.7% in low air pollution vs. 6.9% in high). ANOVA comparing percent change from baselines between the four exposure conditions were non-significant (p=0.195).Mixed effect analysis showed a significant decrease from baseline in BDNF post physical activity when adjusted for covariates (Coef. -13.39, 95%CI -25.64 to -1.15, p=0.032). Single pollutant mixed effect models were non-significant for elemental carbon, ultrafine particles, nitric oxides, and particulate matter < 10 and 2.5 micrometers in diameter. Conclusions: In contrast to previous findings our study suggests that short term moderate physical activity in both, low and high levels of traffic related air pollution, decreases serum BDNF levels.