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Climate change linked to post-traumatic stress disorder for the first time

The study shows exposure to climate triggered events like wildfires can have long lasting effects on cognition.

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By Mark Waghorn via SWNS

Climate change has been linked to post-traumatic stress disorder for the first time.

Wildfires in California caused mental problems and altered brainwaves in humans.

Cognition remained affected for up to a year afterward - and was accompanied by greater activity in the frontal cortex.

The findings based on 725 Californians highlight the long-term negative impact of global warming, say scientists.

Lead author Gillian Grennan, a Ph.D. student at California University in San Diego, explained: "As the planet warms, more and more individuals face extreme climate exposures.

"Hence, novel resiliency tools need to be investigated from multiple perspectives.

"Here, we provide an important neuro-cognitive mechanistic target for future intervention, which may serve as a complement to other socio-behavioral intervention targets."

The study shows exposure to climate-triggered events like wildfires can have long-lasting effects on cognition, particularly the ability to process information in the presence of visual interference.

PTSD after combat or a violent attack has become a recognized and much-discussed phenomenon.

Symptoms can include flashbacks, nightmares and even physical sensations such as pain, sweating, nausea or trembling.

But the behavioral and physiological effects of severe climate stress is less well-known.

Wildfires, hurricanes and other weather disasters are expected to increase in the future.


The analysis used behavioral testing and EEG (electroencephalography) brain scans to examine cognitive ability in a subset of 48 individuals six to 12 months after the Californian Camp Fire more than four years ago.

It was the deadliest and most destructive in the state's history, claiming at least 85 lives.

Participants were tested on standard cognitive tests to assess selective attention, inhibitory control, interference processing and working memory.

The researchers found 27 who had been directly exposed subsequently had greater difficulty in processing sensory information from a visual scene quickly and accurately.

Problems arose when it was surrounded by distracting or conflicting stimuli. This was compared with 21 peers who had not been impacted.

Simultaneous EEG recordings showed those who were exposed to the wildfire also had greater activity in the frontal cortices of their brains.

This indicated they were actually putting forth more cognitive effort, and still not performing as well. These findings are similar to what is seen in PTSD.

Grennan said: "In our sample, 67 percent of the individuals directly exposed to the fire reported having experienced recent trauma, while 14 percent of the indirectly exposed individuals and no non-exposed controls reported recent trauma exposure.

"Fire-exposed individuals showed significant cognitive deficits, particularly on the interference processing task and greater stimulus-evoked fronto-parietal activity as measured on this task.

"Across all subjects, we found that stimulus-evoked activity in left frontal cortex was associated with overall improved interference processing efficiency, suggesting the increased activity observed in fire exposed individuals may reflect a compensatory increase in cortical processes associated with cognitive control.

"To the best of our knowledge this is the first study to examine the cognitive and underlying neural impacts of recent climate trauma."

Communities and mental health experts could expect similar stress responses and cognitive difficulties after future wildfires and severe climate events, and should be ready with proven interventions that ameliorate interference processing."

Grennan said: "Our study shows climate trauma may affect cognitive and brain functions especially with regard to processing of distractions. This knowledge is useful because it will help guide our efforts to develop targeted intervention strategies."

The wildfire was named after Camp Creek Road, its place of origin. It started on November 8, 2018, in Northern California's Butte County.

Ignited by a faulty electric transmission line, the fire originated above several communities and an east wind drove the fire downhill through developed areas.

Drought was a factor. The town of Paradise, which typically sees five inches of autumn rain by November 12, had only received one-seventh of an inch by that date.

With the arrival of the first winter rainstorm of the season, the fire reached 100 percent containment after seventeen days on November 25.

The Camp Fire covered an area of 153,336 acres, or 240 square miles, and destroyed more than 18,000 structures. Most damage occurred within the first four hours.

Paradise and Concow were almost completely destroyed.

The study was published in the journal PLOS Climate.

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