Background

There is growing evidence for a negative impact of traffic-related air pollution on risk of dementia. However, the contribution of noise exposure to this association has been rarely examined.

Objective

We aimed to investigate the individual and combined effect of noise and air pollution on risk of dementia.

Methods

Data on dementia incidence over a 15 year period was obtained from the Betula project, a longitudinal study on health and ageing. Estimates of annual mean levels of nitrogen oxides (NO_x) at the participants’ residential address were obtained using a land-use regression model. Modelled data provided road traffic noise levels (Leq. 24 h) at the participants’ residential address at baseline. Cox proportional hazard regression was used to calculate hazard ratios (HR).

Results

Of 1721 participants at baseline, 302 developed dementia during the follow up period. Exposure to noise levels (Leq. 24 h) > 55 dB had no significant effect on dementia risk (HR 0.95; CI: 0.57, 1.57). Residing in the two highest quartiles of NO_x exposure was associated with an increased risk of dementia. The risk associated with NO_x was not modified by adjusting for noise. Moreover, we found no significant interaction effects between NO_x and road traffic noise on dementia risk.

Conclusion

We found no evidence that exposure to road traffic noise, either independently or in combination with traffic air pollution, was associated with risk of dementia in our study area. Our results suggest that pollution should be considered the main component in the association between traffic related exposures and dementia.

中文翻译：

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道路交通噪音，空气污染和痴呆症风险– Betula项目的结果

背景

越来越多的证据表明，与交通有关的空气污染对痴呆症的危害有负面影响。但是，很少研究噪声对这种关联的影响。

客观的

我们旨在调查噪声和空气污染对痴呆症风险的个体和综合影响。

方法

从Betula项目获得了15年期间痴呆症发病率的数据，该项目是一项有关健康和老龄化的纵向研究。使用土地利用回归模型获得参与者住所地址的年平均氮氧化物（NO _x）的估算值。建模数据提供了参与者在基线时的住宅地址处的道路交通噪声水平（Leq。24小时）。使用Cox比例风险回归来计算风险比（HR）。

结果

在基线时的1721名参与者中，有302名在随访期内发展为痴呆。暴露于噪声水平（Leq。24小时）> 55 dB对痴呆风险没有显着影响（HR 0.95； CI：0.57、1.57）。在NO的两个最高四分居住_X暴露与老年痴呆症的风险增加有关。与NO有关的风险_X不是通过调整噪声修改。此外，我们没有发现之间没有显著交互效应_X和痴呆的危险道路交通噪声。

结论

我们没有发现证据表明，在我们的研究区域，暴露于道路交通噪声（独立或与交通空气污染的组合）与痴呆症的风险有关。我们的结果表明，污染应被视为与交通相关的暴露与痴呆症之间联系的主要组成部分。