Psychological concomitants of the 11 September 2001 terrorist attacks: A review

Abstract

This paper reviews 118 empirical studies detailing the psychological implications of the 11 September 2001 terrorist attacks. Negative outcomes are summarized under five major headings: sub‐clinical distress, acute stress disorder and post‐traumatic stress disorder, depression, substance abuse and suicide, and the use of health services and prescription drug use. In the immediate aftermath of the attacks, a significant minority of those residing in New York City and Washington, DC showed evidence of poor mental health. Within six months of the attacks, however, symptoms typically returned to baseline or lower levels. Within the rest of the United States, the psychological impact of the attacks was minimal; in other countries, it was almost non‐existent. Important psychological and demographic moderators of these outcomes are discussed, in addition to some positive psychological outcomes of the attacks. The paper concludes with a brief review of the empirical research conducted following the 2004 Madrid and 2005 London bombings in order to assess the generalizability of the 9/11 research literature to psychological reactions to other similar events. Implications for practice and policy are discussed, along with the shortcomings of the literature and some suggestions for future research.

Keywords:

• terrorism
• 9/11
• mental health
• post‐traumatic stress disorder
• depression
• resilience

Acknowledgments

I am indebted to Peter Suedfeld, the editors, and two anonymous reviewers for helpful comments on earlier versions of this paper. This research was supported by a CGS Doctoral Fellowship from the Social Sciences and Humanities Research Council of Canada and a Senior Graduate Fellowship from the Michael Smith Foundation for Health Research.

Notes

1. Among the victims were also an estimated 500 foreign nationals from 91 countries (Hirschkorn, 2003).

2. In this same study, media exposure was found to be unrelated to both conduct disorder and hostile attribution bias. In fact, according to the authors, neither direct nor indirect exposure to the events of 11 September exerted a strong or consistent effect on the adolescent outcomes.

3. A few studies found evidence of physiological markers of stress. For example, a decrease in parasympathetic tone was found among 12 coronary artery disease patients during the week of 11 September 2001 (thought to increase susceptibility to other cardiac problems) (Lampert, Baron, McPherson, & Lee, 2002). Similarly, increases in the number of symptoms reported involving the respiratory system or general chest symptoms were noted during the month following the attacks among a large sample of active duty military personnel (Eckart et al., 2004). The results among studies of children, however, are weaker, in that increases in cardiovascular reactivity were found on only two out of seven measures in the months following 9/11 (Gump, Reihman, Stewart, Lonky, & Darvill, 2005), while the incidence of recurrent abdominal pain did not change in the months following 9/11 (Gobble, Swenny, & Fishbein, 2004).

4. The levels of symptoms and functional impairment exhibited by these children were also found to be at a lower level than a group of children assessed following the 1994 Northridge earthquake.

5. These children were all beneficiaries of military health insurance.

6. Forty‐nine percent of these parents also scored above the clinical cut‐off for PTSD, suggesting a higher incidence among the children of parents who are also suffering from PTSD.

7. Defined as cognitive and behavioral efforts to modify or eliminate the stressor (Folkman & Lazarus, 1980).

8. Other indirect evidence also suggests that an increase in the use of health services in NYC could be largely traced to individuals suffering from PTSD, as although awareness of a free counseling program (Project Liberty) in NYC was found to be relatively low (24%) among a sample of 2001 adults, a majority of individuals from poor income background and with symptoms of post‐traumatic stress said they would contact the program (Rudenstine, Galea, Ahern, Felton, & Vlahov, 2003).

9. This figure includes 70% of those suffering from PTSD.

10. Another 3.7% sought informal help.

11. The strongest effect of media exposure was for watching images of people falling or jumping off the WTC. Those who saw this were more than seven times more likely to have clinical depression (Ahern et al., 2002).

12. Defined as keeping one's worries or concerns to oneself because they make others feel uncomfortable (Bonanno et al., 2005).

13. The only exception to this general rule was a study of 1928 nationally representative Italians, which found youth to be positively associated with better mental health one month after 9/11 (although this finding did not take into account pre‐existing differences in mental health between these two age groups) (Apolone et al., 2002).

14. The majority of studies that assessed the role of ethnicity coded it as a categorical variable (i.e. white vs non‐white).

15. Very few individuals appeared to lose their faith as a result of the 9/11 attacks. In one study, for example, only three participants (<1% of the sample) turned away from their faith after 9/11 (Ai et al., 2005)

16. Among this sample, 78% had faith in the efficacy of prayer in coping with stress, while 62% of them actually used prayer to cope with 9/11‐related stress (Ai, Tice, Peterson, & Huang, 2005b).

17. In seeking to define which terrorist attacks might be considered ‘large‐scale’, one method is to count the number of civilian casualties. While this is admittedly a crude and imperfect measure, using a rule of 100 or more civilian casualties yields a list of 35 major terrorist attacks that have taken place worldwide since 11 September 2001 (Terrorism Research Center, 2008). Interestingly, between 1974 and 2001 (inclusive), only 22 terrorist attacks on this scale took place, reinforcing the notion of a fundamental shift in the nature of terrorism worldwide.

18. Refers to positive outcomes reported subsequent to experiencing a traumatic event, as measured by the post‐traumatic growth inventory (Tedeschi & Calhoun, 1996).

19. Reports of case studies (e.g. Whalley, Farmer, & Brewin, 2007) and studies of flashbulb memory (e.g. Ost, Granhag, Udell, & Roos af Hjelmsäter, 2008) are not included in this tally.

20. The reliability of this estimate is unclear, given a response rate of only 10% in this study.

21. Given that the vast majority of this research literature is oriented towards negative outcomes, the file‐drawer problem (the reality that studies with null findings are less likely to be published) may also be of larger concern here than usual. That is, the number of studies reviewed here that do not find a negative effect of 9/11 might be dwarfed by the actual number of such studies.