Air Pollution Linked to Dementia: Study Highlights Biological Underpinnings
A new study sheds light on the biological underpinnings that may explain the association between air pollution and the development of dementia.
Introduction
A study published in the journal Neurology has revealed that high levels of homocysteine and low levels of methionine are associated with an increased risk of dementia in the presence of air pollution. Homocysteine is an amino acid associated with an increased risk of cardiovascular disease (CVD) and dementia, while methionine is an amino acid that serves as a precursor of homocysteine.
Study investigator Giulia Grande, MD, PhD, a postdoctoral researcher at the Aging Research Center, Karolinska Institute, Stockholm, Sweden, stated that her team was able to establish the harmful effects of pollution on human health in Stockholm, a city with low levels of pollution. These effects were mediated by the levels of these amino acids. She emphasized the need to intensify the control of emissions in more polluted cities due to their known negative health effects.
A Known Dementia Risk Factor
“Air pollution is now acknowledged as a possible risk factor for dementia; however, we have a poor understanding of the biological underpinnings of the association between air pollution and dementia,” said Grande.
Animal and human studies have shown that polluted air can lead to higher brain amyloid-beta deposition and neurodegeneration. Previous research has also demonstrated that methionine is involved in normal brain function, and low levels have been linked to dementia and brain aging. On the other hand, high levels of homocysteine have been associated with vascular and cellular damage, which can lead to brain structure damage.
The mechanisms behind the association between high homocysteine levels, low methionine levels, and dementia are complex and not fully understood. While there has been limited research on the impact of air pollution on these amino acids, one recent study showed a positive association between high levels of particulate matter and homocysteine, as well as low levels of methionine.
The researchers aimed to investigate the possible mechanisms and determine whether altered blood concentrations of these two vitamin B-related amino acids could explain the link between air pollution and dementia. They also examined the role of cardiovascular diseases (CVDs) in this association and whether homocysteine and methionine have an independent mediating effect.
Study Design and Findings
The study used data from the ongoing SNAC-K study, a population-based longitudinal study of adults aged 60 years and older living in central Stockholm’s Kungsholmen district. The study followed 2512 dementia-free participants aged 60-78 years every 6 years, while those aged 78 and older were followed every 3 years.
Results showed a 70% increased hazard of dementia per unit of increased PM2.5 exposure during the 5 years before baseline. PM2.5 consists of pollutant particles of less than 2.5 microns in diameter suspended in the air. The dementia risk per unit increase of PM2.5 during the 5 years prior to baseline was also higher after adjusting for other factors.
Approximately 51.6% of the total effect of PM2.5 on dementia was due to mediation and/or interaction with homocysteine, with 6.6% attributable to mediation only and 47.8% attributable to interaction. Almost half of the association could be attributed to a direct effect.
High levels of methionine reduced the dementia hazard associated with PM2.5 exposure by 31%. Around 24.8% of this reduction was attributable to the interaction with methionine, while 25.9% was attributable to the direct effect of PM2.5.
The authors reported that no mediation effect was found through methionine. The impact of homocysteine on cardiovascular conditions partly explains the association, while alternative pathways other than cardiovascular mechanisms may be at play between methionine and dementia.
Implications and Conclusion
The findings of this study further strengthen the evidence that air pollution is detrimental to brain health. The fact that the increased risk is seen even in a country like Sweden, with relatively low levels of pollution, highlights the need for all countries to adhere to the World Health Organization’s strict air quality recommendations.
The study was funded by the Swedish Ministry of Health and Social Affairs, Swedish Research Council, Swedish Research Council for Health, Working Life and Welfare, and several Swedish foundations.
References:
Batya Swift Yasgur, MA, LSW is a freelance writer with a counseling practice in Teaneck, NJ. She is a regular contributor to numerous medical publications, including Medscape and WebMD, and is the author of several consumer-oriented health books as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoir of two brave Afghan sisters who told her their story).
For more Medscape Neurology news, join us on Facebook and Twitter.
SDGs, Targets, and Indicators
SDGs Addressed or Connected to the Issues Highlighted in the Article:
- SDG 3: Good Health and Well-being
- SDG 11: Sustainable Cities and Communities
Specific Targets Under Those SDGs Based on the Article’s Content:
- SDG 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination.
- SDG 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.
Indicators Mentioned or Implied in the Article:
- Air pollution levels (particulate matter PM2.5) as an indicator of environmental impact
- Levels of homocysteine and methionine as indicators of biological underpinnings and risk factors for dementia
The article discusses the association between air pollution and the development of dementia, highlighting the biological underpinnings that may explain this connection. The issues discussed are relevant to SDG 3 (Good Health and Well-being) as well as SDG 11 (Sustainable Cities and Communities).
Based on the article’s content, specific targets under these SDGs can be identified. SDG 3.9 aims to reduce the number of deaths and illnesses from air pollution, which is a hazardous chemical, by 2030. SDG 11.6 focuses on reducing the adverse environmental impact of cities, including air quality, by 2030.
The indicators mentioned or implied in the article include air pollution levels (particulate matter PM2.5) as an indicator of environmental impact, and the levels of homocysteine and methionine as indicators of the biological underpinnings and risk factors for dementia.
Table: SDGs, Targets, and Indicators
| SDGs | Targets | Indicators |
|---|---|---|
| SDG 3: Good Health and Well-being | Target 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination. | – Air pollution levels (particulate matter PM2.5) – Levels of homocysteine and methionine |
| SDG 11: Sustainable Cities and Communities | Target 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management. | – Air pollution levels (particulate matter PM2.5) |
The table summarizes the identified SDGs, targets, and indicators based on the analysis of the article. It provides a clear overview of how the issues discussed in the article align with specific SDGs, targets, and indicators.
Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.
Source: medscape.com
Join us, as fellow seekers of change, on a transformative journey at https://sdgtalks.ai/welcome, where you can become a member and actively contribute to shaping a brighter future.
