A new study of prescription records supports a long-suspected link between wildfires and mental health, indicating that large wildfires appear to exacerbate preexisting mental health conditions, according to a study released by researchers at UW Medicine.

The research, published Feb. 26 in JAMA Open Network, involved analysis of psychotropic prescription data to analyze mental health trends near 25 large California wildfires over eight years.

Researchers found a significant increase in prescriptions for certain psychoactive drugs in the six weeks after fires, each of which burned at least 25,000 acres in the state.

“This research adds a significant amount of evidence that there is a really substantial mental health impact related to wildfire in our communities,” said lead author Zack Wettstein, a UW Medicine emergency medicine doctor.

While investigators have examined the mental health effects of earthquakes, hurricanes and floods, little research has been done on how wildfires affect mental well-being on a population level, Wettstein said.

As climate change continues to alter weather patterns, wildfire activity in the western United States is expected to increase in the coming decades.

“We have a lot of research that supports that wildfires have huge impacts on respiratory health and cardiovascular health,” Wettstein said. “But people don’t think as much about the mental health impacts, which affect all of us. It’s important that we now have stronger evidence that associates wildfire exposure, wildfires in our communities and impacts on our mental health.”

The study, which encompassed 7 million people who lived near large wildfires, found an increase in prescriptions for antidepressants, anxiolytics and mood-stabilizing medications during the fire period, compared with the period before the fire.

There was no parallel increase seen in prescriptions for antipsychotics, hypnotics or the cholesterol-lowering statins – the control drug.

The increases included new prescriptions and refills, and were seen with drugs taken to treat depression, anxiety and bipolar disorder, but not drugs that treat conditions such as psychosis or schizophrenia.

He conducted the study as a guest researcher at the Centers for Disease Control and Prevention with colleague Ambarish Vaidyanathan.

Having worked in emergency rooms near fire events inspired him to study health impacts of California wildfires as a medical student in San Francisco and Fresno where he experienced wildfire smoke and the impacts on patient health firsthand.

The researchers believe this is the first quantitative, multiyear study to examine the impact of wildfires on mental health across multiple years.

The mental health costs of fires near communities is well-known to healthcare providers.

Stressors include exposure to smoke, the potential for evacuation or property loss, and uncertainty.

“As a clinician during wildfire season, I certainly feel like it’s caused me to feel more stressed or affect my sleep,” Wettstein said. “I’ve cared for patients who present for not just the respiratory and cardiovascular disease that we all know about, but also for things like stress and anxiety and exacerbations of their underlying mental health conditions.”

Because the database used in the study included only patients with medical insurance, the research did not consider wildfires’ effects on uninsured people, Wettstein said.

It’s also less clear how wildfire affects rural residents who often have limited access to mental healthcare, he added.

Both populations are likely to have worse mental health outcomes because of increased exposure to fires and decreased access to services, he suggested.

The results underscore the need for a comprehensive public health approach to wildfires that ensures access to services that improve mental resilience before, during and after fires.

“We certainly need more research, but I think this is enough to inform policy discussions around resource allocation,” Wettstein said. “We have a lot of work to do in terms of preparing for and responding to wildfire season from a mental health standpoint.”