Traffic noise and depressive disorders: results of a secondary data-based case control study

Abstract

Introduction: The purpose of this study is to clarify the relation between depressive disorders and traffic noise separately as well as combined for aircraft, road, and railway traffic noise, in a large secondary-data based case-control study. Methods: The study population consisted of individuals that were insured by three large statutory health insurance funds in the Rhine-Main area (administrative region Darmstadt and Rhine Hesse) of Germany. Address-specific exposure to aircraft, road and railway traffic noise in 2005 was estimated. Based on insurance claims and prescription data, 77,295 cases with an incident depressive episode diagnosed between 2006 and 2010 were identified and compared with 578,246 control subjects. Results: For road traffic noise, a linear exposure-risk relationship was found with an odds ratio (OR) of 1.19 (95 % CI 1.12-1.27) for ≥ 70 dB continuous sound levels. For aircraft noise the risk estimates reached a maximum OR of 1.17 (95 % CI 1.13-1.21) at 50 to 55 dB and decreased at higher exposure categories. For railway noise, risk estimates peaked at 60 to 65 dB (OR = 1.13, 95% CI 1.06-1.19). The highest OR of 1.34 (95 % CI 1.25-1.43) was found for a combined exposure to noise above 50 dB from each of these three sources (reference category: individuals without any traffic noise exposure ≥ 40 dB). Conclusion: The results suggest that traffic noise exposure might lead to depression. As a potential explanation for the decreasing risks at high traffic noise levels, vulnerable people might actively cope with noise (e.g. insulate or move away). Given the high proportion of the population that is exposed to traffic noise and the clinical importance of depression, the results are of high public health relevance.