An amazingly naive study below. Some researchers into this topic have absorbed the lesson that they must control for social class variables if they are to be taken seriously but the guys below have just reinvented the wheel.

The study is in a “pay to publish” journal so it’s what one has to expect, I guess. The journal concerned is also a government one so that is a second reason for expecting poor quality.

The authors found that people who lived near busy roads were dumber. But only dumb people would live near busy roads!

Traffic-Related Air Pollution and Cognitive Function in a Cohort of Older Men

By Melinda C. Power et al.

Abstract

Background: Traffic-related particles induce oxidative stress and may exert adverse effects on central nervous system function, which could manifest as cognitive impairment.

Objective: We assessed the association between black carbon (BC), a marker of traffic-related air pollution, and cognition in older men.

Methods: A total of 680 men (mean ± SD, 71 ± 7 years of age) from the U.S. Department of Veterans Affairs Normative Aging Study completed a battery of seven cognitive tests at least once between 1996 and 2007. We assessed long-term exposure to traffic-related air pollution using a validated spatiotemporal land-use regression model for BC.

Results: The association between BC and cognition was nonlinear, and we log-transformed BC estimates for all analyses [ln(BC)]. In a multivariable-adjusted model, for each doubling in BC on the natural scale, the odds of having a Mini-Mental State Examination (MMSE) score ≤ 25 was 1.3 times higher [95% confidence interval (CI), 1.1 to 1.6]. In a multivariable-adjusted model for global cognitive function, which combined scores from the remaining six tests, a doubling of BC was associated with a 0.054 SD lower test score (95% CI, –0.103 to –0.006), an effect size similar to that observed with a difference in age of 1.9 years in our data. We found no evidence of heterogeneity by cognitive test. In sensitivity analyses adjusting for past lead exposure, the association with MMSE scores was similar (odds ratio = 1.3; 95% CI, 1.1 to 1.7), but the association with global cognition was somewhat attenuated (–0.038 per doubling in BC; 95% CI, –0.089 to 0.012).

Conclusions: Ambient traffic-related air pollution was associated with decreased cognitive function in older men.

SOURCE

There was actually something interesting in their data which they promptly “ironed out”: The relationship was non-linear. That may suggest that a medium level of proximity to busy roads was beneficial to IQ! They actually did have something interesting to report but were too fixed onto their mental train-tracks to see it! They threw out the baby and kept the afterbirth

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