Recent research has shown how dangerous smoke is for more than just your lungs. It also affects your brain and can increase your risk of dementia, cognitive problems, or mental health issues.
Every year, the country faces unhealthy levels of air pollution from major wildfires. That includes parts of California, Oregon, and Montana, as well as the Northern California Park Fire, the fifth-largest fire in state history.
Studies
Several studies over the past few years have shown that tiny particles of smoke negatively affect brain health.
“A lot of the research on wildfire smoke has historically focused on our lungs and our hearts,”
Said Stephanie Cleland, an assistant professor at Simon Fraser University who studies the health effects of wildfire smoke.
“A shift to focusing on cognitive outcomes and brain health is more recent.”
A study presented Monday at the Alzheimer’s Association International Conference suggests that wildfire smoke may increase the likelihood of being diagnosed with dementia.
To study this topic, scientists took the medical records of more than 1.2 million older adults aged 60 and older from 2009 to 2019.
The statistics also needed to take into account where people lived. This was needed to determine their exposure to fine particles from wildfire smoke and other forms of pollution. The study found that the likelihood of developing dementia increased by 21% in areas with more fires. Participants were exposed to it for an average of three years.
Exposure to these same fine particles from other sources, such as cars or factories, was associated with a 3% increase in the likelihood of developing dementia.
“These are preliminary results, but they confirm that exposure to wildfire smoke contributes to cognitive decline”
Says Holly Elser, PhD, the study’s author and a neurology resident at the Hospital of the University of Pennsylvania.
However, the threshold at which wildfire smoke becomes a risk for dementia is not yet clear.
There are more and more wildfires every year. This is due to climate change, which is also increasing the exposure of many people to smoke. The frequency of extreme wildfires has more than doubled from 2003 to 2023.
How wildfire smoke affects the brain
Scientists believe that tiny particles in it can cross the barrier between the bloodstream and the brain. This causes inflammation in the central nervous system. Particles can also enter the brain directly through the nose. This, of course, can affect people’s ability to think, learn, and remember.
Dementia is not the only potential consequence of wildfire exposure. An earlier study in 2022 found that adults performed worse in a brain training game. The game measured skills such as memory, attention, flexibility, processing speed, and problem-solving.
“In the hours and days following exposure to wildfire smoke, we see a significant decline in people’s ability to pay attention,” said Cleland, one of the study’s authors.
Another study published that same year found that a school year lowered students’ test scores compared to a smoke-free year.
“The more smoke you breathe in, the worse you do on tests,” said Marshall Burke, an associate professor of global environmental policy at Stanford University and a co-author of the study.
Elser acknowledged that there are still many unexplored questions about how smoke affects the brain. It’s unclear, for example, whether smoke causes dementia in healthy people or only in those already at risk.
The Fire-Depression Link
A February study found that smoke affects the mind. It increased emergency room visits for anxiety. Air pollution has also been shown to influence the development of depression and psychotic disorders, such as schizophrenia.
Scientists speculate that smoke from wildfires alters the neurochemistry in people’s brains. This is what causes depression and anxiety. But it’s also possible that the anxiety and stress of experiencing or living through a wildfire may independently lead to mental health problems.
Scientists have studied other health effects of wildfire smoke much better. Scientists have known for decades that when people inhale small smoke particles, they can penetrate deep into the lungs or enter the bloodstream. This increases the risk of asthma, stroke, heart attack, lung cancer, and more.
To reduce exposure to wildfire smoke, experts recommend:
- Avoiding outdoor activities
- Closing all windows
- Using indoor air filters
- Wearing an N95 mask if they must go outside