Those effects sometimes last for years. Another study, published in 2008 in Journal of the American Public Health Association, looked at the effect of 9-11 on the mental health of office workers in Chicago, far away from the actual site of the attacks in New York and Washington.
University of Illinois at Chicago researchers found that subjects who had fears and beliefs shaped by the attacks in 2003 tended to have problems such as increased depression, anxiety, hostility, post-traumatic stress and drinking in a followup survey two years later.
Judith A. Richman, a UIC professor of epidemiology in psychiatry who led the study, said she suspects that the recent attacks in France could be having similar effects upon Americans' mental health.
"For people watching the news, and reading about the threats to Washington and New York that followed the Paris attacks," she said, "this all may have revived their anxiety."