Stress from last year's deadly Japan earthquake and tsunami caused a part of some survivors brain to shrink, scientists studying post-traumatic stress disorder have discovered.
The study, published in the Molecular Psychiatry journal, compared brain scans of 42 healthy adolescents in the disaster-hit Tohoku region taken in the two years before the disasters with new images taken three to four months afterwards.
Those participants who had symptoms of post-traumatic stress disorder were also found to have suffered a shrinking in the orbitofrontal cortex, a part of the brain involved in decision-making and the regulation of emotion.
"The changed volumes in the orbitofrontal cortex are correlated to the severity of PTSD symptoms," author Atsushi Sekiguchi said.
Previous studies had already suggested that PTSD patients undergo changes to the brain, but this is the first to pinpoint which part of the organ is altered by trauma.
The subjects all lived in an inland area of the quake-ravaged city of Sendai.
"Not only the earthquake itself, but also frequent after-quakes, radioactive materials leaked from nuclear plants, and many inconveniences after the quake, such as stopping utilities, caused stressful periods" for the subjects, Sekiguchi said.
About 19,000 people died when a 9.0-magnitude earthquake off the northeastern coast of Japan on March 11 last year triggered a tsunami, followed by a meltdown at the Fukushima nuclear plant.
"These findings provide a better understanding of posttraumatic responses in early stage of adaptation to the trauma and may contribute to the development of effective methods to prevent PTSD," the report said.