Dementia risk may increase as air quality worsens

Exposure to particulate matter (PM) less than 2.5 microns in diameter_2.5) was associated with an increased risk of dementia, a meta-analysis suggested.

14 studies that assessed PM_2.5the overall risk of dementia was increased by 4% for every 2 μg/m (HR 1.04, 95% CI 0.99-1.09).³ Increase in annual average PM_2.5 According to Marc Weisskopf, PhD, ScD, and colleagues at the Harvard TH Chan School of Public Health in Boston:

However, of the seven studies that used active case ascertainment, a method that included face-to-face assessments of people who did not have dementia at baseline, dementia risk was elevated by 42% (HR 1.42, 95% CI 1.00-2.02), co-authors reported in Weisskopf and BMJMoreAfter excluding four studies due to possible concerns about time trend bias and causal timeframes, the more conservative estimate is HR 1.17 (95% 0.96-1.43), the researchers said. says.

Among seven studies that used passive monitoring methods such as electronic health records, the HR was 1.03 (95% 0.98-1.07).

“This is a big step forward in providing actionable data for regulators and clinicians in terms of understanding the state of the literature on this very important health topic,” Weiskopf said in a statement.

“The results can be used by organizations such as the Environmental Protection Agency. [EPA]Considering tightening PM regulations_2.5 “Our findings support the public health importance of such measures.”

This study is the first systematic review and meta-analysis using active case ascertainment. It is also the first study to use a new risk of bias in non-randomized studies of exposure (Robbins-E) This tool provides a structured approach for assessing bias in observational epidemiological studies.

“Evidence that reduced air pollution is associated with lower rates of dementia is still emerging,” said Dr Andrew Sommerlad, both of University College London and Kathy Liu of MRCPsych. I’m here. Accompanying editorial.

The editors observe that this new systematic review highlights that many uncertainties remain about the link between air pollution and dementia. “The risk factors for dementia are clustered together, many of them driven by socioeconomic status, and the interactions between risk factors are likely to be complex,” they noted.

“Many studies have attempted to address this issue by controlling for potential confounding factors, but manipulation has revealed complex interrelationships between socioeconomic status, ethnic groups, air pollution, and dementia.” This adjustment may not be appropriate, as it may obscure the ,” write Sommerlad and Liu. .

air pollution Modifiable risk factors for dementia Global, PM_2.5 Concentrations in major cities vary widely from 10 µg/m3.³ Over 100 µg/m2 in Toronto, Canada³ In Delhi, India, they added.

In January, the EPA tighten national annual limits About particulate pollution from Suggest an update Meets national ambient air quality standards for fine particulate matter with the goal of lowering major (health-based) annual PM._2.5 standard ~ 9.0 ~ 10.0 µg/m³down from the current cutoff of 12.0 µg/m³.

In their review, Weisskopf and co-authors identified 51 studies that assessed the association between ambient air pollution and clinical dementia. Most studies were from North America or Europe. Some were from Asia or Australia. All publications are from the last ten years.

Researchers used ROBINS-E to assess study bias and included 16 studies in the meta-analysis. Highest rated PM_2.5Some saw nitrogen dioxide, nitrogen oxides, or ozone.

Nine studies found that overall HR per 10 μg/m2³ Nitrogen dioxide was 1.02 (95% CI 0.98-1.06). HR per 10 μg/m in five studies³ Nitric oxide was 1.05 (95% CI 0.98-1.13). No clear association between ozone and dementia was shown.

prime minister_2.5 Findings show that the association between ambient air pollution and clinical dementia is consistent and likely to be consistent even below the EPA annual limit of 12 μg/m3. is showing³ or UK (20 μg/m³) and European Union (25 μg/m³) limitation, the researchers suggested.

“Given the sheer number of dementia cases, identifying actionable and modifiable risk factors to reduce the burden of the disease would have enormous personal and societal impact.” PM exposure_2.5 Other air pollutants can be modified to some extent by individual actions, but more importantly by regulation. ”