The Village Voice chronicles recent studies about 9-11 memories.
The first study they mention is perhaps the most controversial. The authors claim that people who did not experience the traumatic events firsthand do not possess bona fide flashbulb memories. Sharot et al. tested New Yorkers who were either in Downtown (near the Twin Towers) or Midtown when the airplanes struck. They found that Midtown subjects recalled 9-11 memories with no more emotional engagement than memories of other autobiographical experiences such as summer vacation. Furthermore, only Downtown subjects exhibited selective activation of the amygdala when recalling 9-11 memories, as measured by fMRI. The authors’ claim that Midtown subjects do not possess flashbulb memories is somewhat counterintuitive considering the universality that is normally attributed to memories of 9-11 or JFK’s assassination. The argument is slightly rhetorical, since it is not clear that emotionally-charged recall or amygdala activity should really serve as criteria for identifying flashbulb memories.
The Village Voice also cites a study by Ganzel et al. in which 9-11 witnesses and controls were tested for responses to emotional stimuli not related to the terrorist attacks. They found that witnesses had excessive amygdala activity in response to emotional imagery, suggesting a lasting change in brain circuitry.
Lastly, the article mentions a study of children who lost a parent in the attacks. Children who lost a parent were twice as likely to suffer mental illness, and their saliva samples contained unusually high levels of cortisol, a hormone associated with stress.