Summary: New mouse study shows woodsmoke causes lasting brain inflammation and chemical changes, which may explain long-term effects seen in humans after smoke exposure.
Major Findings:
- Woodsmoke triggered prolonged brain immune cell activation
- Brain chemical alterations gradually increased over a month
- Findings match reports of lasting brain impacts in smoke-exposed people
- Results suggest potential targets to protect the brain from smoke damage
Source: Journal of Neuroinflammation
Woodsmoke Causes Lasting Brain Inflammation & Chemical Changes in Mice
Smoke from wildfires and wood-burning stoves may have lingering effects on the brain, according to new research in mice.
Scientists found that woodsmoke caused immune cells in the brain to remain activated for weeks.
It also gradually altered brain chemistry over a month-long timeframe.
The findings help explain why wildfire smoke has been linked to lasting cognitive and mood problems in humans.
They also suggest new avenues to mitigate neurological damage from inhaled smoke.
Mimicking Real-World Smoke Exposure
Researchers at the University of New Mexico exposed mice to woodsmoke intermittently over 2 weeks. This modeled real-life smoke exposure from wildfires and wood-burning stoves.
The smoke contained fine particulate matter similar to real woodsmoke. The amount of smoke the mice inhaled also matched levels people may experience during wildfires.
After the last exposure, the scientists analyzed the mice’s brains at 1, 3, 7, 14 and 28 days later. They wanted to see how long the effects of breathing woodsmoke persisted.
Inflammation and Immune Activation
The study found woodsmoke triggered neuroinflammation that lasted weeks.
Initially, endothelial cells lining the brain’s blood vessels became activated. But this resolved within about 2 weeks.
In contrast, brain immune cells called microglia remained activated for the entire 28 day period. Other immune cells like neutrophils also infiltrated the brain and persisted for weeks.
This means woodsmoke caused prolonged neuroimmune activation in mice, even after exposures stopped.
Lasting Brain Chemical Changes
The scientists also analyzed brain metabolites – the small molecule chemicals involved in metabolism.
Metabolite levels in the hippocampus changed dramatically on the first day after smoke exposure. They then rebounded a bit but slowly climbed back up over the 28 day timeline.
Key brain chemicals like neurotransmitters and those related to cell energy were pushed out of balance.
This suggests woodsmoke may alter brain function through metabolic effects.
Matching Human Impact Reports
These findings in mice may help explain effects seen in humans after smoke exposure.
Numerous studies have linked wildfire smoke with lingering cognitive impairment and mental health impacts.
The months-long neuroimmune activation and chemical shifts seen in mice align with these lasting neurological consequences reported in smoke-exposed people.
Potential Ways to Protect the Brain
The results point to endothelial cells and microglia as possible targets for mitigating neurological damage from inhaled smoke.
Anti-inflammatory treatments shortly after exposure could potentially counteract endothelial inflammation. Microglial inhibitor drugs may similarly help suppress chronic immune cell activation.
Nutritional supplements that support neurotransmitter balance and energy metabolism could also aid in recovery after smoke inhalation.
More Research Needed
While intriguing, much more research is still needed to translate these findings to humans. The study used female mice all of the same age. Only one type of woodsmoke at modest concentrations was tested.
It’s unclear if results would differ for males, the elderly, or those with pre-existing conditions. The real-world mix of toxins in wildfire smoke is also more complex.
However, these discoveries provide clues into the neurological impacts of smoke and new directions for protecting the brain. With wildfires worsening worldwide, understanding how to mitigate related health effects will only grow in importance.
References
- Study: Biomass smoke inhalation promotes neuroinflammatory and metabolomic temporal changes in the hippocampus of female mice
- Author(s): David Scieszka et al.
- Date: Aug. 22, 2023
