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See Inside August/September 2007

Continuing Effects of 9/11

High brain activity in people affected by the tragedy could lead to later health problems

Six years after the events of September 11, researchers are beginning to understand the attacks' enduring toll on mental health. Recent studies at New York–Presbyterian Hospital/Weill Cornell Medical College and New York University have shown long-term psychological and neurological repercussions in adult witnesses who were near the World Trade Center and in children who lost a parent in the tragedy.

Researchers at Cornell and N.Y.U. compared brain scans of people who were near the WTC during the attacks and people who were farther away. Both studies found that those who were closer continue to show heightened activity in the amygdala, the part of the brain that regulates emotional intensity and creates emotional memories. In the Cornell study, functional magnetic resonance imaging (fmri) scans showed that people within two miles of the site that day have a hyperactive amygdala as compared with people who lived 200 miles away, even though those nearby were seemingly resilient and show no signs of mental disorder. The N.Y.U. team similarly found that when asked to recall the events of 9/11, twice as many people who were near Ground Zero had elevated amygdala activity as compared with people who were five miles away in midtown Manhattan. Slow recovery of a highly active amygdala, the Cornell researchers say, could increase susceptibility to mental health problems later in life.

The N.Y.U. study also found that the direct experience of 9/11 yielded a type of memory similar to a “flashbulb memory,” the exceptionally vivid, confident and multisensory recollection of a shocking public event. Those near the WTC who saw, heard and smelled the results of the attacks showed depressed activity in the parahippocampal cortex, which encodes neutral peripheral details. This altered brain activity might help explain how flashbulb memories are formed and why they seem to last longer than other types of memories.

Another study conducted at Cornell followed 45 bereaved children who lost a parent in the disaster. Despite the fact that most received therapy during the two years following their loss, the prevalence of psychiatric illness in these children doubled from 32 percent before 9/11 to nearly 73 percent afterward. Anxiety, post-traumatic stress and separation anxiety were the most common afflictions. The grieving children also had chronic elevations of the stress hormone cortisol in their saliva, suggesting that their bodies' “fight or flight” mechanisms remained switched on. According to the researchers, long-term cortisol elevation may lead to hypersensitivity to stress later in life, which in turn could cause cognitive impairment, weak bones, and insulin resistance.

Understanding the biology underlying these vulnerabilities will help treat people who experienced this and other traumas, the researchers say.

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