NEW DELHI, Aug 24: The pervasive health consequences of air pollution in the national capital may extend beyond respiratory and cardiovascular ailments, with a comprehensive review by Delhi University professors indicating a potential link between prolonged exposure to fine particulate matter (PM2.5) and adverse effects on the brain.
Information was available with The Chenab Times that the review of 129 peer-reviewed studies suggests that long-term exposure to PM2.5 can trigger inflammation and oxidative stress within the brain. These processes can disrupt the function of brain cells, interfere with the protective blood-brain barrier, and potentially allow the smallest particles to infiltrate the central nervous system via the olfactory pathway.
According to the research, conducted by academics from the Department of Environmental Studies at Delhi University, a substantial body of evidence now connects chronic exposure to air pollutants with cognitive impairment and detectable structural and functional changes in the brain. These alterations span across various life stages, from development to aging.
Vandana Mishra, a researcher involved in the study, stated that air pollution is increasingly recognised not just as a threat to lung and heart health, but also as a significant concern for brain health. She noted that research is now linking long-term particulate matter exposure to cognitive decline, impaired neurodevelopment, and biological processes associated with neurodegenerative conditions like Alzheimer’s and Parkinson’s diseases.
The review highlights that fine particulate matter has been observed to breach the blood-brain barrier, a critical concern arising from pollution exposure. Studies cited in the review have reported region-specific structural and functional alterations in the human brain due to chronic exposure to ambient air pollution, particularly PM.
Neuroimaging and other investigative studies have documented reductions in brain volume and cortical thickness, with particular attention paid to the frontal and temporal lobes, which are crucial for cognitive functions. These observed structural changes have been associated with difficulties in memory, attention span, and executive functions such as planning and decision-making.
Furthermore, the review points to evidence of changes within the hippocampus, a brain region vital for memory formation and consolidation, as well as disruptions in the neural connections between different parts of the brain. In older adults, this long-term exposure has been linked to reduced brain volume and impaired hippocampal function, alongside changes in the prefrontal cortex and increased white-matter abnormalities.
The researchers have cautioned against interpreting these findings as definitive proof that air pollution alone causes neurological diseases. The existing evidence primarily focuses on structural and cognitive changes rather than confirmed diagnoses of conditions like Alzheimer’s or Parkinson’s. Nevertheless, the findings raise significant concerns for the developing brains of children and young people.
Studies reviewed have reported reduced grey and white matter volumes in children exposed to air pollution, with potential impacts on IQ, attention, and behavioural regulation. Research into prenatal and early-life exposure has also suggested a correlation between pollution exposure and impaired cognitive development, as well as lower intelligence scores in children. Early-life exposure is noted to affect biological pathways essential for brain development and synaptic plasticity, the process by which brain cell connections are formed and strengthened.
The concern is not confined to younger demographics. The review indicates evidence of subclinical neurodegenerative changes in otherwise healthy young adults, suggesting that prolonged pollution exposure could potentially contribute to premature brain aging. The review posits that multiple biological processes may interact to produce these neurological effects.
Exposure to PM2.5 can activate microglia, the brain’s resident immune cells, leading to neuroinflammation, which can negatively impact nerve cells and their interconnections. Air pollution can also induce oxidative stress, causing damage to cellular components like proteins, fats, and DNA, and affecting mitochondria, the powerhouses of brain cells. The hippocampus and prefrontal cortex, areas with high energy demands and critical roles in learning and decision-making, may be particularly vulnerable.
The review also draws attention to the role of metals and other toxic substances carried by particulate matter. These elements can interfere with intercellular communication and impact white matter development, especially in the developing brain. For residents of Delhi, where exposure to particulate pollution is a persistent daily reality, this research adds a critical dimension to the understanding of the city’s air quality crisis, suggesting that the effects of polluted air may be insidious and extend to neurological health over time.
The Chenab Times News Desk