Association of PTSD symptoms in U.S. population with 9/11 terrorist attack

Arneta MayesResearch Seminar – March 2010/Graduate StudiesUniversity of New Haven, West Haven, CT

Association of Post-Traumatic Stress Disorder (PTSD) Symptoms in U.S. Population with 9/11 Terrorist Attack

Introduction:

The terrorist attack in New York on September 11, 2001 was the largest act of terrorism in U.S. history. Individuals throughout the country were affected in a variety of ways.

Early post-event research a revealed a substantial prevalence of psychological symptoms and probable psychological syndromes in New York City, in the months after the attacks.[i] Post-Traumatic (PTSD) is one of the syndromes documented.

Post-traumatic stress disorder is a severe anxiety disorder that develops after exposure to a traumatic event.

[i] http://www.bullyonline.org/stress/ptsd.htm, February 24, 2010

Introduction (cont’d)

The diagnostic criteria for Post Traumatic Stress Disorder (PTSD) as defined in DSM-IV is that a person must experience a traumatic event in which both of the following were present: 1) the person experienced or witnessed or was

confronted with an event or events that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others and

2) the person's response involves intense fear, helplessness, or horror.[i]

[i] http://www.bullyonline.org/stress/ptsd.htm, February 24, 2010

Introduction (cont’d)

Research Question: Did the traumatic event of the terrorist attack

on September 11, 2001, result in an increase of post-traumatic stress disorder symptoms in the adult population in the United States?

Literature Review:

A New York City study reported that 44 percent of Americans were bothered by at least one of five symptoms of post-traumatic stress disorder (PTSD) in the first 3–5 days after September 11.

A population-based survey conducted 1 month after September 11 found that 7.5 percent of residents of Manhattan living south of 110th Street had symptoms consistent with a diagnosis of probable PTSD related to the attacks and that 9.7 percent of respondents had symptoms consistent with major depression.

A Web-based epidemiologic survey reported a prevalence of probable PTSD of 11.2 percent in the New York City metropolitan area. This estimate was almost three times higher than estimates for the rest of the country.[i]

[i] http://aje.oxfordjournals.org/cgi/content/full/158/6/514, March 29, 2010

Literature Review (cont’d)

Although the prevalence of PTSD symptoms was consistently higher among persons who were more directly affected by the attacks, a number of persons who were not directly affected by the attacks also met criteria for probable PTSD.

Data suggested rapid resolution of most of the probable PTSD symptoms in the general population of New York City in the first 6 months after the attacks. The psychological consequences of September 11, was believed to extend from persons directly affected by the disaster to persons in the general population.[i]

[i] http://aje.oxfordjournals.org/cgi/content/full/158/6/514, March 29, 2010

Literature Review (cont’d) Symptoms of Post-Traumatic Stress Disorder (PTSD)

There are many symptoms for post traumatic stress. Individuals may experience any combination of these symptoms and the symptoms may be delayed or become more evident at any time following the traumatic event.

The symptoms include: 1) recurring nightmares about the event(s), 2) difficulty sleeping (classified as restlessness in this study, 3) changes in appetite, 4) feelings of anxiety or fear, especially when exposed to events or

situations reminiscent of the trauma (classified as nervousness in this study),

5) jumpiness, edginess, exaggerated startle reflex, or becoming overly alert (classified as nervousness in this study),

6) depression, sadness, a lack of energy, a sense of despair or hopelessness, spontaneous crying (classified as sadness and hopelessness in this study) and

7) feeling "scattered" or "off center", unable to focus on work or daily activities and difficulty making decisions or carrying out plans (classified as effort and restlessness in this study).[i]

[i] http://www.wright.edu/~scott.williams/LeaderLetter/trauma.htm, February 24, 2010

Methodology (cont’d)

Results from surveys conducted annually by the National Center for Health Statistics, Centers for Disease Control and Prevention (CDC) in the form of The National Health Interview Survey (NHIS) were used for this study. The NHIS administers face-to-face interviews in a nationally representative sample of households. Each week a probability sample of the civilian non-institutionalized population of the United States is interviewed by personnel of the U.S. Bureau of the Census. For the Sample Adult questionnaire, one civilian adult (18 years or older) per family is randomly selected; generally this individual must self-report responses to questions.[i]

Utilizing SPSS, the Sample Adult Survey data for the years 1998-2004 was compiled into a merged data file consisting of 222163 cases. A random sample of 50% was generated using SPSS resulting in a data file consisting of 110841 cases.

[i] http://www.cdc.gov/nchs/nhis/about_nhis.htm. March 30, 2010


Data frequencies are as follows:

By Gender:

Sex

Frequency Percent

Valid Percent Cumulative Percent

Male 48438 43.7 43.7 43.7

Female 62403 56.3 56.3 100.0

Valid

Total 110841 100.0 100.0

By Race:

race_all

Frequency Percent

Valid Percent

Cumulative Percent

Minority No 87897 79.3 79.4 79.4

Minority Yes

22862 20.6 20.6 100.0

Valid

Total 110759 99.9 100.0

Missing Miissing 82 .1

Total 110841 100.0


By Region:

Region

Frequency

Percent

Valid Percent

Cumulative Percent

Northeast 17700 16.0 18.6 18.6

Midwest 21929 19.8 23.0 41.6

South 34607 31.2 36.3 77.9

West 21055 19.0 22.1 100.0

Valid

Total 95291 86.0 100.0

Missing System 15550 14.0

Total 110841 100.0


Adult respondents were asked: “During the past 30 days, how often did you feel:

1) So sad that nothing could cheer you up 2) Nervous 3) Restless or fidgety 4) Hopeless 5) That everything was an effort, or 6) Worthless.

The response range was 1-All of the time 2-Most of the time 3-Some of the time 4-A little of the time 5-None of the time 7-Refused, and 9-Don’t know.

Variables regarding symptoms were entered as ordinal data and for purposes of this analysis, responses to questions regarding the PTSD emotions were recoded into reverse order, with the highest numeral indicating the highest degree of emotion.


Survey administration dates were originally coded by Survey Year and Year Quarter. A cut-point was created by computing a new variable which split the data into before and after the September 11, timeline. However, because only quarterly date information was available the cut-point was made for the beginning of the Fourth Quarter in 2001. The variable for the survey cut-point was entered as ordinal data as 1-Before September 11 and 2-After September 11.

It was necessary to recode the Race category for the purpose of this study as the course of the NHIS administration of the survey, race was coded into variables that corresponded with the survey year of administration. Race categories were recoded into “Minority No” and “Minority Yes” in dichotomy format utilizing 0 and 1, respectively.

Regional data was converted from nominal to dichotomy format.



Threats to validity:

Region In 2004 NHIS removed Region from its

Adult Sample data set and data regarding region is missing from the 2004 cases. This resulted in a total of 14 percent in missing cases, however, no empty cell alerts presented during the Chi-Square analysis regarding region.


Threats to validity: (cont’d)

Gender: The Chi-square analysis attributed emotional values

to males, that could be considered female behaviors. Four of the symptoms showed a significant association for males only, as follows sadness .004, nervousness .001, restlessness .000, and worthlessness .000.

An examination of the data (using the example of sadness below) revealed that female responses followed expected patterns and more females responded positively to feeling sad “most of the time”. However, the number of female respondents was higher than the number of male respondents.

Methodology (cont’d)Crosstab

Count

911 Timeline

GenderRecode Before 9/11 After 9/11 Total

NONE of the time 20437 17247 37684

A LITTLE of the

time

2818 2301 5119

SOME of the time 1799 1574 3373

MOST of the time 524 470 994

ALL of the time 199 175 374

Don't know 155 152 307

Not ascertained 1 1 2

How often felt sad, past

30 days

Refused 269 316 585

Male

Total 26202 22236 48438

NONE of the time 23346 19499 42845

A LITTLE of the

time

5002 4278 9280

SOME of the time 3667 2926 6593

MOST of the time 1029 937 1966

ALL of the time 439 324 763

Don't know 199 181 380

Not ascertained 6 4 10

How often felt sad, past

30 days

Refused 305 261 566

Female

Total 33993 28410 62403


This re-examination of the significance of the Chi-square values confirmed the original finding that there was no significance indicated for sadness in association with the 911 timeline for females. Chi-Square Tests

GenderRecode Value df

Asymp. Sig.

(2-sided)

Pearson Chi-Square 20.954a 7 .004

Likelihood Ratio 20.880 7 .004

Linear-by-Linear

Association

14.293 1 .000

Male

N of Valid Cases 48438

Pearson Chi-Square 12.099b 7 .097


Linear-by-Linear

Association

.001 1 .974

Female


a. 2 cells (12.5%) have expected count less than 5. The minimum

expected count is .92.

b. 1 cells (6.3%) have expected count less than 5. The minimum

expected count is 4.55.


Because gender was a recoded value (0, 1 dichotomy), in order to check the integrity of the recoding process, another Chi-square analysis was conducted utilizing the original variable of “sex” which was coded as ordinal data (1, 2). It returned the same values as the recoded analysis. Chi-Square Tests

Sex Value df

Asymp. Sig.

(2-sided)

Pearson Chi-Square 20.954a 7 .004


Linear-by-Linear

Association

14.293 1 .000

Male


Pearson Chi-Square 12.099b 7 .097


Linear-by-Linear

Association

.001 1 .974

Female


a. 2 cells (12.5%) have expected count less than 5. The minimum expected count is

.92.

b. 1 cells (6.3%) have expected count less than 5. The minimum expected count is

4.55.

Analysis and Findings:

A Chi-square analysis was conducted in order to determine whether there was an association between the PTSD symptoms of the respondents and the timeline cut-point of October 1, 2001.

All PTSD symptoms, as dependent variables, showed a significant association to the independent variable of the timeline as follows:

Sadness .011 Nervousness .003 Restlessness .001 Hopelessness .000 Effort .000 and Worthlessness .002.

However, the directional and symmetrical measures for sadness and restlessness were not significant.

Additionally, the directional and symmetrical measures for nervousness were negative indicating a negative association with the timeline.

The finding of significant association of PTSD symptoms to the timeline could not be replicated when the controls, of gender, race, and region were applied in the Chi-square testing.

Analysis and Findings (cont’d)Gender:

Significance was present for both genders in the domains of hopelessness (M=.000/F=.006) and effort (M=.001/F=.031)

Four of the symptoms showed a significant association for males, only, as follows sadness .004, nervousness .001, restlessness .000, and worthlessness .000.

Analysis and Findings (cont’d)Race:

Regarding race there was no significant association of PTSD symptoms for Minorities to the 911 timeline other than in the domain of nervousness.

Analysis and Findings (cont’d) Nervousness was significant for both Non-

Minorities .001 and for Minorities .039. However, the directional measure was

negative for minorities regarding nervousness -.013 and the gamma was also negative -.026 indicating that being a member of a minority had a negative association with nervousness.

A Spearman’s Rho analysis revealed that a negative predictability existed between race status and nervousness prior to the application of the timeline

Analysis and Findings (cont’d)

Correlations

race_all

How often felt sad, past 30

days

How often felt

nervous, past 30

days

How often

restless/fidgety, past 30

days

Correlation Coefficient

1.000 .048** -.032** -.017**

Sig. (2-tailed) . .000 .000 .000

race_all

N 110759 110759 110759 110759


.048** 1.000 .513** .507**

Sig. (2-tailed) .000 . .000 .000

How often felt sad, past 30 days

N 110759 110841 110841 110841


-.032** .513** 1.000 .641**

Sig. (2-tailed) .000 .000 . .000

How often felt nervous, past 30 days

N 110759 110841 110841 110841


-.017** .507** .641** 1.000

Sig. (2-tailed) .000 .000 .000 .

Spearman's rho

How often restless/fidgety, past 30 days

N 110759 110841 110841 110841

**. Correlation is significant at the 0.01 level (2-tailed).

Analysis and Findings (cont’d) Reduced nervousness with minority

status is evident in a 2007 report by the CDC on NHIS survey data:

Percent of population with feelings of nervousness or restlessness, among persons 18 years of age and over, 2007

Non-Hispanic

Black

Non-Hispanic

White

Non-Hispanic Black/ Non-Hispanic White

Ratio Nervousness, all or

most of time 2.9 3.8 .8

Nervousness, some of time

8.8 10.4 0.8

Restlessness, all or most of time

3.7 5.2 0.7

Restlessness, some of time

9.6 11.4 .8

Source: CDC 2009. Summary Health Statistics for U.S. Adults: 2007. Table 16.

http://www.cdc.gov/nchs/data/series/sr_10/sr10_240.pdf[PDF | 8.43MB] 1

1 http://minorityhealth.hhs.gov/templates/content.aspx?lvl=3&lvlID=9&ID=6474, March 30, 2010

Analysis and Findings (cont’d) There was no significance in directional

and symmetrical measures for Non-Minorities in the domain of nervousness.

Other significant associations for Non-Minorities are as follows: sadness .001, restlessness .001, hopelessness .000, effort .000, worthless .000.

Analysis and Findings (cont’d) Controls for region of the county were applied as Northeast,

Midwest, South and West, utilizing the regions as originally grouped in the NHIS dataset.

The only region that showed consistent significance in the association of PTSD symptoms to the 911 timeline was the Northeast with sadness .000, nervousness .000, restlessness .000, hopelessness .000, effort .000 and worthlessness .000.

The South showed no association for the domains of sadness, hopelessness, effort or worthlessness. The association of nervousness for the South was .004 with a significant negative directional measure of -.019 and a negative gamma of -.037 indicating that living in the South resulted in a negative association with nervousness. The association of restlessness of the South was .014 and this also had a negative directional measure -.016 and a negative gamma of -.031, again indicating a negative association specific to region.

Analysis and Findings (cont’d)

Similar to minority status a Spearman’s rho matrix revealed an inverse association with nervousness existed for the Southern region exclusive of the 911 timeline. Correlations

SOUTHRECODE

How often felt nervous, past 30

days

How often

restless/fidgety, past 30

days

How often felt hopeless, past 30

days


1.000 -.048** -.029** -.014**

Sig. (2-tailed) . .000 .000 .000

SOUTHRECODE

N 95291 95291 95291 95291


-.048** 1.000 .641** .478**

Sig. (2-tailed) .000 . .000 .000

How often felt nervous, past 30 days

N 95291 110841 110841 110841


-.029** .641** 1.000 .491**

Sig. (2-tailed) .000 .000 . .000


N 95291 110841 110841 110841


-.014** .478** .491** 1.000

Sig. (2-tailed) .000 .000 .000 .

Spearman's rho

How often felt hopeless, past 30 days

N 95291 110841 110841 110841


Analysis and Findings (cont’d) The West duplicated the South in that it also

showed no association for the domains of sadness, hopelessness, effort or worthlessness.

The association of nervousness for the West was .030 with a significant negative directional measure of -.023 and a significant negative gamma of -.041. The association of restlessness of the West was .013 and this also had a negative directional measure -.23 and a negative gamma of -.044.

Analysis and Findings (cont’d) However unlike the South the negative directional

measures were specific to the 911 timeline analysis. A Spearman’s rho correlation did not reveal negative directional value prior to the application of the 911 timeline to the analysis for the Western region.

Correlations

WESTRECODE

How often felt nervous, past 30

days

How often

restless/fidgety,

past 30 days

How often felt hopeless, past 30

days


1.000 .012** .002 .022**

Sig. (2-tailed) . .000 .640 .000

WESTRECODE

N 95291 95291 95291 95291


.012** 1.000 .641** .478**

Sig. (2-tailed) .000 . .000 .000

How often felt nervous, past 30 days N 95291 110841 110841 110841


.002 .641** 1.000 .491**

Sig. (2-tailed) .640 .000 . .000


N 95291 110841 110841 110841


.022** .478** .491** 1.000

Sig. (2-tailed) .000 .000 .000 .

Spearman's rho

How often felt hopeless, past 30 days N 95291 110841 110841 110841


Analysis and Findings (cont’d) The Midwest showed no significant

association in the domains of sadness, nervousness or worthlessness. The association of hopelessness for the Midwest was .027, effort was .019.

Analysis and Findings (cont’d) Bivariate and partial correlations were conducted to in order to analyze

the relationships between control variables and the timeline. Restlessness and sadness showed no significance.

All of the significant bivariate correlations were significant at the 0.01 level (2-tailed) with the exception of nervousness which was significant at the .0.05 level (2-tailed)

Regarding the timeline influence on nervousness (with a correlation co-efficient of -.007, control variables proved to be more explanatory than timeline with correlation coefficients as follows: gender indicating the greatest potential for predictability .065, followed by the South -.036, race -010, Northeast .022, and Midwest .016.

The timeline and effort correlation coefficient was .014. The variable of race was more of a predictor with a correlation co-efficient of .046, followed by gender .034.

The correlation coefficient for timeline and hopelessness was .017. The variable of race was more of a predictor at .026, followed by gender .024, and Northeast .021

The correlation coefficient for timeline and worthlessness was .012, however race proved to be more of a predictor at .018, followed by northeast .016, South -.016, and gender .015

Conclusion:

The terrorist attack on September 11 did not result in an increase of PTSD symptoms in the U.S. population in all test groups. While there is significant association of PTSD symptoms to the September 11 timeline, the association was not replicated across the controls of gender, race and region of the country. A contributing factor to this finding may be that studies have found that “people's reactions differ depending on their proximity to the disaster, their gender and their particular coping mechanisms”.[i]

While the findings were significant to the timeline, the values of association and correlation were weak.

Consistent with previous literature regarding proximity to the actual September 11 attack, the Northwest was the only region that demonstrated a consistent association and correlation of PTSD symptoms to the 911 timeline.

[i] http://www.apa.org/monitor/sep02/learned.aspx, March 30, 2010

Indications for New Research:

The Office of Minority Health, a division of the U.S. Department of Health & Human Services reports that African Americans are 30% more likely to report having serious psychological distress than Non-Hispanic Whites.[i]

African-Americans are also reported to have higher rates of sadness, feelings of worthlessness and feelings that everything is an effort as indicated below:

However, contrastingly, African-Americans are less likely to report as being “nervous” in light of stressors that are inherent with minority status. Indications for new research would be study that would provide insight regarding why these challenges do not result in increased feelings of nervousness.

[i] http://minorityhealth.hhs.gov/templates/content.aspx?lvl=3&lvlID=9&ID=6474, March 30, 2010

Percent of population with feelings of sadness, hopelessness, worthlessness, or that everything is an effort, all of the time, among

persons 18 years of age and over, 2007

Non-Hispanic Black

Non-Hispanic White

Non-Hispanic Black/ Non-Hispanic White

Ratio Sadness 3.7 2.4 1.5

Hopelessness 1.9 1.8 1.1 Worthlessness 1.3 1.8 .7 Everything is an

effort 6.8 4.5 1.5

Indications for New Research: (cont’d)

The Northeast accounts for twenty-five percent of the nation’s GDP as of 2007[i]. It would be beneficial to understand how residual symptoms of PTSD might affect economic output (e.g., relationships in the workplace).

[i] http://en.wikipedia.org/wiki/Northeastern_United_States. March 30, 2010

Documents

Association of PTSD symptoms in U.S. population with 9/11 terrorist attack