Air pollution may promote onset, progression of motor neuron disease

Exposure to air pollution may put people at risk of developing motor neuron disease or progression for those who already have the disease, according to a study from Sweden.

The study included 1,463 patients (mean age 67.3 years, 55.6 percent male) with motor neuron disease, 7,310 population controls (mean age 67.3 years, 55.6 percent male), and 1,768 sibling controls (mean age 65.5 years, 48.3 percent male).

In the population comparison, both short-term and long-term air pollution were associated with an increased risk of motor neuron disease. The odds ratios (ORs) per interquartile range (IQR)-increment in the 1-year average exposure were 1.12 (95 percent confidence interval [CI], 1.02–1.23) with PM_2.5, 1.25 (95 percent CI, 1.15–1.36) with PM_2.5-10, 1.25 (95 percent CI, 1.14–1.36) with PM₁₀, and 1.20 (95 percent CI, 1.12–1.29) for NO₂. The corresponding ORs per IQR-increment in the 10-year average exposure were 1.21 (95 percent CI, 1.09–1.34) with PM_2.5, 1.30 (95 percent CI, 1.19–1.42) with PM_2.5-10, 1.29 (95 percent CI, 1.18–1.42) with PM₁₀, and 1.20 (95 percent CI, 1.12–1.29) with NO₂.

Among patients with motor neuron disease, a higher concentration of PM₁₀ or NO₂ was associated with an increased risk of mortality (per IQR increment in the 1-year average exposure: hazard ratio [HR], 1.30, 95 percent CI, 1.12–1.50 and HR, 1.23, 95 percent CI, 1.10–1.36, respectively).

A higher level of 10-year average exposure to PMs was associated with greater odds of fast progression, as indicated by the total ALS Functional Rating Scale-Revised (ALSFRS-R) score being in the upper 25th percentile (per IQR increment in PM_2.5: OR, 1.34, 95 percent CI, 1.02–1.77; PM_2.5-10: OR, 1.31, 95 percent CI, 1.06–1.61; PM₁₀: OR, 1.30, 95 percent CI, 1.03–1.66).