Millions of Americans were glued to their TV sets on the morning of September 11, 2001 and on the following days, watching live coverage and repetitive replays of scenes that they would never have expected to see outside of a disaster movie. High-profile claims were subsequently made that American had suffered prolonged negative mental and physical effects of these events, exacerbated by excessive viewing of them on television.
Further claims were made that the mental and physical damage did not depend on television viewers being at immediate direct risk from the events at the World Trade Center in New York and Pentagon in Washington DC or having loved ones being in danger or actually being killed or hurt. A case was being made for a virtual trauma conveyed by the media and that the nationwide effects of 9/11 were proof that posttraumatic stress reactions could be elicited and persist in the absence of a direct exposure to events. If valid, these claims would suggest the need to expand the boundaries of events considered necessary to cause posttraumatic stress disorder. The prevailing wisdom had been that it required direct exposure or direct personal relevance of an event, such as the violent death of a spouse or child, to cause posttraumatic stress reactions. Otherwise, any psychiatric disturbance would represent something else, maybe a general anxiety disorder or major depression.
This is a crucial distinction. The symptoms of posttraumatic stress response are highly subjective and have considerable overlap with general distress, including normal responses to everyday stresses. Similarly, the symptoms of posttraumatic stress disorder overlap considerably with other psychiatric disorders. Presumably, what is distinctive about
posttraumatic is a demonstrable tie of the symptoms to a serious event.
One set of claims appeared in the high-impact JAMA: Journal of the American Medical Association. Another claim that the events of 9/11 and their viewing on TV caused heart ailments appeared in a later companion piece in the Archives of General Psychiatry. The American Psychological Association was sufficiently impressed by these claims to fly one of the authors of the two articles, Roxanne Silver to Washington DC to testify before Congress and then invited her to contribute an unprecedented three papers to a special issue of the American Psychologist devoted to the psychological effects of terrorism.
With the 10th anniversary of September 11, 2001 upon us, it would be good to take another look at the evidence that were mustered for these claims, how valid the evidence was at the time, and how this claim stood the test of time. This post will be the first in a series examining the evidence presentedfor these claims in the two articles, how well these claims fit with the rest of the scientific literature, and the implications for just how skeptical a view we should adopt for what we read in the scientific literature and how it is portrayed in the media.
I am going to make case that the authors of these two articles did not present strong evidence that the American people suffered significant mental and physical negative effects from simply learning of the events of September 11, 2001 or watching them on television. These horrific events profoundly changed Americans' lives, but learning of the events or watching on television did not have public health or clinically significant mental and physical effects, if people were not directly affected or in the immediate vicinity of the events. I am going to make a further argument that the authors of these two articles made it quite difficult to compare their claims to other evidence, but it is not impossible, and that other, better quality evidence can be shown to contradict their claims.
The articles are freely available, and so if you would like to do your own skeptical sleuthing and compare your conclusions to mine, you can download them and read them before proceeding. I am going to start with the JAMA article, and I will discuss the Archives of General Psychiatry article in later blog posts. Just click on the highlighted links in this blog post to obtain the articles.
The JAMA article claims that 17% of the US population living outside of New York City had posttraumatic stress symptoms related to September 11 two months after the events and that 5.8% of the population still had the symptoms at six months.
Let's take a look at the evidence that is presented in the article. We will see that there are substantial problems with the measures and with the sample of Americans living outside New York City on which these claims are based.
The study built upon an ongoing project in which participants received free Internet access in return for filling out web-based surveys three or four times monthly. The authors took advantage of this arrangement to administer questionnaires to capture participants' reactions immediately after September 11 and in the following months and years.
Measurement Issues. The measure of Acute Stress Reaction used in this study was a modification of a questionnaire used in other studies, the Stanford Acute Stress Reaction Questionnaire (SASRQ). You can examine a copy of the original questionnaire by clicking on this link. The authors claimed that items were scored in terms of the American Psychiatric Association Diagnostic and Statistical Manual Of Mental Disorders, Fourth Edition (DSM-IV) criteria for Acute Stress Disorder, but that is not quite accurate.
The DSM-IV requires that symptoms of Acute Stress Disorder have a duration of 2 days to 4 weeks and interfere with functioning. The reason for the duration criterion is to exclude either transient symptoms or more enduring symptoms that may indicate a chronic disorder, not an acute one. In addition to inquiring about the duration of symptoms, the original questionnaire allows respondents to indicate how frequently they experienced the symptom in a specified time period using a six-point scale ranging from "not at all experienced" to "very often experienced". However for the purpose of the 9/11 study, the authors did not ask about duration and they provided only a simple yes/no option for whether respondents had experienced particular symptoms. In doing so, the authors lost considerable crucial information.
It is not clear why the authors did what they did to the existing measure, but we can safely assume that respondents from the normal general population will often be reporting on symptoms only lasting a day or chronic recurring symptoms independent of an event, particularly when they are asked to evaluate an event that did not directly affect them personally.
A diagnosis of Acute Stress Response requires that people meet an impairment criterion-- that their personal functioning was negatively affected by their symptoms. This is intended to exclude reactions that can be considered part of a normal reaction. Unfortunately, the authors of the study did not collect information as to whether the complaints respondents were reporting actually interfered with their functioning
The items on the questionnaire cover quite general complaints. Look at the questionnaire and you will see that items assess such complaint as feeling restless, difficulty falling asleep, and not wanting to talk about the event. Interpretation of these phenomena in terms of a stress response assumes that someone - in the case of a questionnaire, the respondents -- can accurately distinguish whether the symptoms only came after the event and can be attributed to the exposure to particular event. Yet, note that for the purposes of the study the authors are suspending the assumption that direct exposure is necessary. Before participants were confronted with the web-based questionnaire, they may never have even thought to attribute their symptoms to the events of 9/11, and they may simply have been noting that they had symptoms when they completed the questionnaire, regardless of their presumed cause.
