Archives of Clinical Neuropsychology, Vol. 13, No. 5, pp. 455–471, 1998
Copyright  1998 National Academy of Neuropsychology
Printed in the USA. All rights reserved
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Amnestic Disturbance and Posttraumatic Stress
Disorder in the Aftermath of a Chemical
Release
Rosemarie M. Bowler and Christopher Hartney
San Francisco State University
Long Hun Ngo
University of California, Berkeley
Neuropsychological assessments were performed on 70 patients referred after a Catacarb chemical
release in a Northern California town. After appropriate exclusions, the 59 patients used in the
final analysis were mostly White (66%), with 56% having some college level education. They were
administered the: Wechsler Adult Intelligence Scale-Revised (WAIS-R), Memory Assessment Scale
(MAS), Trails A and B, Stroop, Controlled Oral Word Association Test (COWAT), Fingertapping
Test, Purdue Pegboard, Dynamometer, Rey 15-Item Test, Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Brief Symptom Inventory (BSI), Beck Depression Index (BDI), Profile of Mood
States (POMS), and Impact of Events Scale (IES) scales in addition to a health questionnaire and
symptom checklist. Results indicate impaired scores on mnestic function and information processing
when compared to Heaton’s (1992) normative data, and the MAS norms (Williams, 1991). MMPI2, BSI, BDI, POMS, and IES results indicate significant elevations on scales of depression, anxiety,
anger, and posttraumatic stress disorder (PTSD) symptoms. The more brief tests of affect and mood
appear sufficiently sensitive in measuring the dysphoric mood in group research studies. Clinical
diagnoses using criteria from the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV; American Psychiatric Association, 1994) criteria indicate a prevalence of 54% PTSD
and 64% Amnestic or Cognitive disturbance. New onset of dermatological, respiratory, visual, and
gastrointestinal symptoms and illnesses are consistent with the chemical exposure, the PTSD may
be in reaction to it, and Amnestic/Cognitive disturbance, from both an organic and functional etiology.  1998 National Academy of Neuropsychology. Published by Elsevier Science Ltd
This study was performed without funding. This clinical study was in part undertaken by the senior author to thank
the community for having negotiated funding for the epidemiological health study of their town after they incurred
the Catacarb release.
The authors thank participants giving permission to have their clinical results compiled in this study. Thanks
also goes to Dr. R. Heaton and Dr. M. Williams for their review; Dr. S. Rauch for his most helpful editorial assistance;
Drs. S. Rauch and A. Rosenberg for their assistance in administering some of the neuropsychological tests; and K.
Lloyd for assistance with data management and analysis. The authors also thank Drs. D. Greenly, A. Duhan, J.
Kaplan, A. Condey, N. Payne and Ms. P. Marlow for referring the patients.
Address correspondence to Rosemarie M. Bowler, 8371 Kent Drive, El Cerrito, CA 94530. E-mail: rbowl@
sfsu.edu
455
456
R. M. Bowler, C. Hartney, and L. H. Ngo
A recent oil refinery chemical release in the San Francisco Bay Area was shown to cause
adverse health effects in the residents of an adjacent town. An epidemiological survey investigation showed increased reporting of adverse mood and cognitive symptoms for the residents
of the exposed town, in addition to headaches, respiratory, visual, gastrointestinal, and dermatologic complaints (Bowler, Ngo, Hartney, Tager, Midtling, & Huel, 1997). Exposure relationships with increased symptoms, worsening of illnesses, and increased medication use
were found. Many of those residents who also had complaints of mood and memory disturbance were referred for individual neuropsychological evaluation.
EXPOSURE CHARACTERISTICS
Catacarb, the chemical solution released by the refinery, is a mixture of various chemical
compounds and has been commonly used by refineries since the early 1970s. The chemical
compounds, described in more detail in the previous study (Bowler et al., 1997), include
potassium carbonate; potassium borate; potassium metavanadate; and diethanolamine (DEA).
These components of Catacarb have been shown to be respiratory, gastrointestinal, and dermatological irritants (Melnick, Mahler, Bucher, Hejtmancik et al., 1994; Melnick, Mahler,
Bucher, Thompson et al., 1994; U.S. Department of Health and Human Services Public
Health Service Agency for Toxic Substances and Disease Registry, 1995). While potassium
carbonate is considered relatively harmless, high doses of potassium borate have been found
to be associated with central nervous system effects, birth defects and reproductive problems
in animals. Vanadium (potassium metavanadate) overexposure also has been shown to affect
the nervous system, and may be a carcinogen (Bofetta, 1993). Moreover, DEA, may also have
been transformed into the highly CNS toxic N-nitrosodiethanolamine (N-DEAL; Cosmetic
Ingredient Review, 1983). However, the neuropsychological sequelae of Catacarb or of most
of its components has not previously been studied.
Actual Catacarb exposure levels are difficult to estimate for a variety of reasons. No blood
or urine samples of the town residents and no air samples were taken at the time of the
release. The few environmental measurements for Catacarb deposits, which were performed
many weeks after the release and resulted in inconsistent estimates, depending on the sampling location and method. Furthermore, a lack of reliable information concerning several
factors, including the exact proportions of the Catacarb composition, the rate and volume of
release, and the behavior of the chemicals once released, make estimation difficult. Two risk
assessments, one performed by a company hired by the oil company and the other performed
by local experts for the community, produced widely divergent estimates of deposition of
Catacarb of 0.1 to 12 g/m2 and 1 to 15 g/m2, respectively, with total Catacarb released estimated at 200,000 to 232,000 pounds over the 16 days (see Montgomery Watson, 1996).
However, the company risk assessment toxicologists who reported the lowest rates of exposure acknowledged that there is a likelihood of health effects resulting from short-term atmospheric exposures to Catacarb (Montgomery Watson, 1996). This lack of accurate estimates
of exposure resulted in an inability to construct a dose/response exposure index. Moreover,
the uncertainty of exposure levels served to heighten concern by the residents.
PTSD AND CHEMICAL EXPOSURE
Prior reports of chemical accidents and disasters have documented an increase in the prevalence of posttraumatic stress disorder (PTSD; Bowler, Mergler, Huel, & Cone, 1994; Freed,
Bowler, & Fleming, 1996; Green, 1991). Chemical exposures are experienced as traumatic
events by many of those who are exposed. PTSD symptoms can develop rapidly following
Amnestic Disturbance and PTSD After Chemical Release
457
the onset of acute toxicant-related health symptoms and associated psychological traumas
from chemical exposures. Even after initial acute health symptoms reside, exposed persons
commonly have residual fears of long-term adverse health outcomes and, not infrequently,
lingering PTSD symptoms (Bowler et al., 1994, Green & Solomon, 1995). PTSD symptoms
have been described extensively since the last century (Janet, 1889). Both physical and psychological symptoms are an integral part of PTSD. Diminished amnestic and cognitive function has been shown concomitant with mood disturbance. The impaired functioning in PTSD
patients has been postulated to be due to sympathetic hyper-reactivity (McFarlane, Atchison,
Rafalowicz, & Papay, 1994) and psychobiologic mechanisms (Charney, Deutch, Krystal, Southwick, & Davis, 1993; Van der Kolk, 1994; Van der Kolk, McFarlane, & Weisaeth, 1996).
Recent reviews of PTSD describe the seriousness of the disorder, its difficulty in treatment,
and its physiological correlates. Van der Kolk (1994) and Van der Kolk et al. (1996) postulate
involvement of the prefrontal cortex and subsequent impairment of memory in PTSD patients.
Kolb and Mutilipassi (1982) also show how the excessive stimulation of the adrenal cortical
system of the CNS during trauma may result in neuronal change. In a recent study by Bremner
et al. (1995), these hypotheses were confirmed; reduced hippocampal volume in Vietnam
PTSD veterans compared to matched to non-PTSD controls was shown unequivocally.
The reported increased prevalence of PTSD, with its challenges in treatment and identified
physiological correlates, has now become recognized as a serious and unique psychiatric
disorder. Kinzie and Goetz (1996) review the history of PTSD nomenclature and show that
even the recently included criteria for diagnosis of PTSD in recent editions of the Diagnostic
and Statistical Manual of Mental Disorders (DSM-III; American Psychiatric Association,
1980; DSM-III-R; American Psychiatric Association, 1987; DSM-IV; American Psychiatric
Association, 1994) are still not inclusive of the typical reactions seen in PTSD victims. While
the DSM-IV diagnostic criteria include some of the usual symptoms of intrusion and avoidance with concomitant physiological arousal, they do not include the type of personality
change frequently seen after exposures to human-made traumas (e.g., hostility, distrust, social
withdrawal, and social isolation) which are, however, listed in the International Classification
of Diseases 10th Revision (ICD-10) since 1992.
A large proportion of the residents exposed to the Catacarb release had complaints of
cognitive, amnestic, and mood dysfunction. Those residents identified by medical practitioners at a temporary clinic as having gross abnormalities in memory, cognition, and mood
(approximately 10% of those who sought medical attention) were subsequently referred for
extensive neuropsychological assessments. Over one half of those referred for neuropsychological assessments were examined by the author who administered a comprehensive neuropsychological test battery. The results of these neuropsychological assessments were used
to investigate the prevalence of Amnestic and/or Cognitive (Amnestic/Cognitive) disturbance
and abnormalities in mood. The standardized normative data by Heaton (1992) and Williams
(1991) were used to compare the exposed residents to those of the standardization samples.
Symptom and medical illness data were reviewed to examine the relationship between chemical exposure and physical effects.
METHOD
Participants
Of a total of 140 patients who were referred for neuropsychological assessment from the
temporarily established medical clinic, 70 were administered a neuropsychological test battery by the senior author. The referrals were made by physicians who examined the patients
at the temporary medical clinic established 6 months after the Catacarb release. Patients were
458
R. M. Bowler, C. Hartney, and L. H. Ngo
referred for further neuropsychological evaluation if they were found to have mental status
abnormalities or complaints of mood changes since the chemical exposure. The majority of
the patient referrals and testing occurred between 8 to 16 months after the Catacarb release.
Medical practitioners chose the referral neuropsychologist in a somewhat randomized fashion, based in part on distributing the load of new referrals among three neuropsychologists,
with approximately one half sent to the senior author, because she had conducted the epidemiologic study of the town and was experienced in evaluating the effects of neurotoxicants.
Evaluation data of individual patients tested by the other neuropsychologists, often using
slightly different tests, are not included here, but a cursory review of results revealed similar
diagnoses across all examiners.
Sample selection. All 70 neuropsychological participants of this study were reviewed for
inclusion/exclusion criteria, resulting in exclusion of 11 participants from the analysis. Bases
for exclusions were prior neurological disease (n 5 2); prior self-reported alcohol or drug
abuse (n 5 4); malingering, as determined by clinical observation of the examiner combined
with validity scale scores of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2),
consistency of scores across tests assessing the same domain of function, scores on the Rey
15-item (minimum of 7 out of 15), and scores on the Portland Digit Recognition tests (n 5
1); age of less than 17 years (n 5 2); or tested beyond the cut-off date (n 5 2). In all, 59
participants were retained for the present analysis. Table 1 shows the demographic characteristics of the final group. The group was primarily a White middle-aged sample with similar
levels of education (68% had at least some college) similar in these respects to the entire
exposed town in the 1990 U.S. Census.
Measures
The neuropsychological test battery employed consists of the following tests: the Wechsler
Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981), the Memory Assessment
Scales (MAS; Williams, 1991), Golden’s (1978) version of the Stroop Color Word Test, the
Cancellation H Test (Diller et al., 1974), the Rey 15-Item Visual Memory Test (Rey, 1964),
the Controlled Oral Word Association Test (COWAT; Benton & Hamsher, 1976; Spreen &
Strauss, 1991); the Trail Making Tests A and B (Lezak, 1995), the Purdue Pegboard Test
(Purdue Research Foundation, 1948); and the manual Fingertapping and Dynamometer Tests
(Lezak, 1995). The Portland Digit Recognition (Binder, 1993) test was given when judged
necessary to confirm or rule out malingering.
Tests of affect and mood were the MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, &
Kaemmer, 1989), the Brief Symptom Inventory (BSI; Derogatis, 1993), the Beck Depression
Index (BDI; Beck & Steer, 1987), the Profile of Mood States (POMS; McNair, Lorr, &
Droppleman, 1992), and the Impact of Events Scale (IES; Horowitz, Wilner, & Alvarez,
1979).
Participants also completed health questionnaires identical to those used in the epidemiological health study of the exposed town, including relevant demographics, medically diagnosed illnesses, habits, and a symptom checklist.
Procedure
Participants completed informed consent forms giving permission for their test results to
be used without identifiers in group research reports and publications. All referrals were made
directly by the clinic physicians and interpretive reports of the testing results were sent to
them.
Amnestic Disturbance and PTSD After Chemical Release
459
After taking their initial clinical histories, the senior author administered the tests of mood,
attention and concentration and malingering. The remaining tests of motor function, the
WAIS and the MAS were administered by one of two additional experienced clinicians. The
participants were encouraged to give their very best performance at all times and were given
rest periods as needed. The same order of testing was followed throughout and all tests were
administered according to the instructions in the manual. Although the specific history of each
participant was known to the senior author, the two assisting clinicians were not informed of
the particular exposure background of the participants. Following completion of the test scoring, interpretation and report, a 1-hour follow-up appointment with the senior author was
arranged to inform participants of their test results and diagnoses, to discuss the implications,
and to make further referrals as appropriate.
The senior author, who was responsible for the interpretation of the test data, was independent of any litigation process, as she had been required to abstain from legal testimony for
either the plaintiffs or the oil company as a condition of funding the prior epidemiologic
health study.
Medical history. Medical records were requested from the referring physicians and were
reviewed for each participant. It was found that 22 (37%) were diagnosed with pulmonary
and 5 (9%) with cardiac disorders, 9 (15%) with each dermatologic illness, and hypertension
26 (44%) with only 5 (9%) having the diagnosis of hypertension prior to the chemical release.
Scoring. Each participants test scores for the WAIS-R, Fingertapping Test, Dynamometer,
and Trailmaking Tests A and B were compared to the normative databases developed by
Heaton and colleagues using the Heaton computer program (Heaton, Grant, Matthews, &
the PAR Staff, 1991; Heaton, 1992). The comprehensive norms for the expanded HalsteadReitan Battery (HRB) were chosen because (a) their normative group had similar age and
education levels to the group of participants studied, and (b) the normative database includes
adjustments for age, sex, and the computation of individual T-scores that facilitate interpretation in the absence of an appropriate control group. The MAS is already adjusted for age
and education and, therefore, also permits a comparison with the normative data collected
by Williams (1991). The Stroop Color Word Test was also adjusted for age according to the
manual by Golden (1978), and T-scores are reported for each of the Word, Color, and ColorWord tests. The BSI, BDI, and the MMPI-2 were scored according to the respective manuals
with a T-score of 50 representing the mean of the normative populations. The MMPI-2 was
scored to include the Posttraumatic Stress Disorder (PTSD-Pk) scale by Keane, Malloy, and
Fairbank (1984). For the POMS, a computer program was used for scoring, with a T-score
of 50 representative of the outpatient psychiatric sample reported by McNair et al. (1992).
The was scored according to the directions by Horowitz, Wilner, and Alvarez (1979) for a
total IES score and for the subscales of Intrusion and Avoidance.
Diagnostic critieria. For a clinical diagnosis of PTSD, Anxiety, or Depression, the presence
of the DSM-IV criteria were determined from the clinical history, observation and results of
the mood tests. A necessary diagnostic indicator for PTSD was the history of new onset of
intense psychological distress associated specifically with the experience of the Catacarb
exposure coupled with distressing and frightening recollections and dreams, and intruding
thoughts. For the diagnosis of either cognitive or amnestic disturbance (n 5 38), the primary
diagnostic indicators were derived from scores indicating impairment in cognitive and memory function (i.e., when scores on these tests were lower than scores on word knowledge,
prior schooling, and vocational achievement). Cognitive Disorder diagnoses were assigned
when cognitive functions were at least mildly impaired on three or more tests of cognitive
460
R. M. Bowler, C. Hartney, and L. H. Ngo
function and Amnestic Disorder diagnoses were assigned whenever the dysfunction consisted
primarily of lowered memory scores.
Statistical Analysis
Descriptive statistics were used to characterize the participant groups demographic characteristics, symptoms, diagnosed illnesses, neuropsychological test scores, and diagnoses. Student’s t-tests were calculated comparing the participant group test scores with the appropriate
normative data.
Chi-square analysis compared the health questionnaire and medical record data for the
participant group with that of the residents of the exposed town and the unexposed control
town (collected in the previous epidemiologic study). This analysis included comparing the
prevalence of symptoms and illnesses suggestive of organic chemical causes. Pearson correlations assessed possible associations between the toxic symptom data and test scores.
For the HRB adjusted tests, impairment is defined as one standard deviation below the
mean of the standardized samples by Heaton et al. (1991) and Heaton (1992). Because one
standard deviation below the mean (lowest 16th percentile) can be considered a somewhat
liberal cut-off for relatively mild impairment, which could result in overpathologizing, cutoff scores of one and one half standard deviations below the mean (lowest 7th percentile)
for moderate impairment and two standard deviations below the mean (lowest 2nd percentile)
for severe impairment were computed for the WAIS-R, additional HRB tests, and for the
MAS. Using these binary outcomes (impairment/no impairment), the chi-square test of goodness-of-fit and prevalence ratios were computed at one, one and one half, and two standard
deviations below mean expectation to estimate the likelihood of impairment at each level.
To correct for a potential multiple comparison error, a more conservative alpha level was
adopted ( p # 0.01). (Alpha levels of p , .05 are shown in the tables for comparison purposes
only.)
Correlational analyses between the MMPI-2 D and Pt scales and the scales assessing
depression and anxiety on the BSI, BDI, and POMS were performed. Pearson correlations
assessed possible associations between the most prevalent diagnoses and test scores.
RESULTS
Table 1 shows descriptive statistics for the demographic variables, with a mean age of
43.9 (SD 5 13.1), 56% female, 66% White, and 67.8% with at least some college. This
sample and the HRB normative samples were similar on all demographic variables except
ethnicity. Comparing the demographic characteristics of this clinical sample to those of the
larger epidemiologic sample of the town, it can be noted that residents assessed for neuropsychological impairment were younger (M 5 44 years vs. M 5 52 years), had slightly lower
college education (68% vs. 72%) and greater non-White status (34% vs. 9%). No differences
on demographics nor test scores were found for those referred early (8 months after the
chemical release) or later (16 months after). Eighty-five percent (n 5 50) of the sample
reported being in litigation concerning the release; no differences were found between litigants and nonlitigants on the demograhic variables.
Table 2 shows the mean scores for the WAIS-R, without gender and education adjustments, and the mean scores for motor, visuomotor, Stroop Color Word, and Rey tests. Stroop
mean scores are approximately one standard deviation below the mean of the normative data
reported by Golden (1978). The motor and visuomotor test scores appear to be within normal
limits according to the norms from Heaton (1992). On the Rey 15-Item Visual Memory Test,
Amnestic Disturbance and PTSD After Chemical Release
461
TABLE 1
Demographics (N 5 59)
Gender
Male
Female
Race
African American
White
Hispanic
Asian
Other
Non-White
White
Marital status
Single
Married
Divorced
Widowed
Other
Education
High school or less
Some college
Associate of Arts degree or more
Job type
Managerial/professional
Administrative support
Service
Farming/forestry
Precision production
Operators/laborers
Student
Other
Age
M 6 SD
Range
n
Number of children
M 6 SD
Range
n
n
%
26
33
44.1
55.9
4
39
7
4
5
20
39
6.8
66.1
11.9
6.8
8.5
33.9
66.1
8
34
9
3
5
13.6
57.6
15.3
5.1
8.5
19
33
7
32.2
55.9
11.9
7
6
4
3
4
6
3
13
15.2
13
8.7
6.5
8.7
13
6.5
28.3
43.92 6 13.09
17–78
59
1.64 6 1.52
0–6
53
Note. M 5 mean; SD 5 standard deviation.
all retained participants scored in the nonmalingering range; all but two participants scored
above 9 on the total number recalled, with the mean and median score being 13.
Table 3 shows the percentage of participants impaired, Prevalence Ratios, and Chi-square
significance at one, one and one half, and two standard deviations below the mean for the
WAIS-R, Trail Making Tests A and B, Finger Tapping, and Dynamometer tests using the
Heaton (1992) corrections. Significant differences between expected and observed scores
were found at one standard deviation for WAIS-R Arithmetic, Trail Making A and B, and
Dynamometer (Prevalence Ratios ranging from 1.9 to 5.3); and at two standard deviations
for Nondominant Fingertapping (Prevalence Ratio 4.3). Similarities approached significance
at the level of one and one half standard deviations.
Table 4 shows the mean scores for the MAS Summary Memory Indices and its respective
subtest scores. The participants scored lower than expected on all of the memory indices and
on all subtests except Cued List Recall.
Table 5 shows the percentage impaired, Prevalence Ratios, and chi-square significance at
462
R. M. Bowler, C. Hartney, and L. H. Ngo
TABLE 2
WAIS-R IQ Scores and Age Scaled Subtest Scores and Other Test Scores
WAIS-R
Scale scores
Full scale score
Verbal score
Performance score
Verbal subtests
Information
Digit span
Vocabulary
Arithmetic
Comprehension
Similarities
Performance subtests
Picture Completion
Picture Arrangement
Block Design
Object Assembly
Digit Symbol
Other Tests
Finger Tapping Test (10 seconds)
Dynamometer
Purdue Pegboard
Errors
Trail-Making tests
Errors
Cancellation tests
Errors
Controlled Oral Word Association test
Stroop Color/Word test
Color
Word
Rey 15-item
M
SD
Range
n
101.65
102.98
101.78
11.83
11.62
11.71
79–129
82–140
79–137
55
55
55
9.56
9.91
10.67
9.84
11.16
11.49
2.58
2.33
2.72
2.49
2.71
2.34
3–16
5–15
6–16
5–17
6–19
6–18
55
55
55
55
55
55
10.42
10.62
10.65
10.61
10.33
2.69
2.72
2.50
2.47
1.96
6–18
5–17
7–17
6–19
6–14
55
55
55
54
55
91.02
51.14
26.65
0.77
122.09
0.45
199.12
4.71
38.97
39.05
39.17
41.92
13.28
17.81
22.6
4.27
0.91
50.15
0.73
53.21
5.96
10.53
9.35
8.53
8.16
2.34
39–122
17–100
13–35
0–3
46–294
0–3
66–309
0–30
17–65
20–62
22–55
20–61
7–15
59
59
57
57
58
58
58
58
58
59
59
59
57
Note. WAIS-R 5 Wechsler Adult Intelligence Scale-Revised; M 5 mean; SD 5 standard
deviation.
one, one and one half, and two standard deviations below the mean for the MAS. Significant
differences between expected and observed scores were found at 1 sd for all scales and
subscales except Cued List Recall (Prevalence Ratios ranging from 2.2 to 3.0); at one and
one half standard deviations for all except Verbal Memory, Verbal Span, List Acquisition,
Visual Reproduction, and Cued List Recall (Prevalence Ratios ranging from 2.8 to 4.6); and
at two standard deviations for Visual Memory, List Acquisition, List Recall, Immediate and
Delayed Prose Recall, Immediate and Delayed Names-Faces, Visual Reproduction, and Immediate and Delayed Visual Recognition (Prevalence Ratios ranging from 4.5 to 10.5).
Table 6 shows the mean scores and t-tests of litigants (n 5 50) versus nonlitigants for
the WAIS-R IQs, MAS Memory Indices, MMPI-2 validity scores, and the Rey. As can be
noted, there were no significant differences with the exception of verbal IQ, which was
slightly lower for the nonlitigants.
More pronounced differences for symptoms were found between this sample and the unexposed control town. Chi-square analyses of the health questionnaire symptom checklist indicate significantly greater prevalence ( p . .001) in this sample compared to the exposed
town for respiratory (95.7% vs. 59.9%), visual (63.0% vs. 30.4%), dermatological (42.0%
vs. 23.4%), headache (93.5% vs. 52.2%), and gastrointestinal (79.6% vs. 42.3%) symptoms.
Two by two chi-square analyses of diagnosed illnesses according to the medical record review
showed no significant differences by clinical diagnoses (PTSD or Amnestic/Cognitive).
Amnestic Disturbance and PTSD After Chemical Release
463
TABLE 3
Percent Impaired for WAIS-R, Trail-Making and Motor Tests (N 5 59) and Risk of
Impairment at 1, 1.5 and 2 Standard Deviations (SD) Below Mean (M) of HRB
Normative Sample
% Impaired (N 5 58), Chi-Square Significance, and
Prevalence Ratio (PR)
1 SD
WAIS-R
Scale scores
Verbal
Performance
Full Scale
Verbal subtests
Information
Digit Span
Vocabulary
Arithmetic
Comprehension
Similarities
Performance subtests
Picture Completion
Picture Arrangement
Block Design
Object Assembly
Digit Symbol
Other tests
Trails A
Trails B
Finger Tap Dominant
Finger Tap Nondominant
Dynamometer Dominant
Dynamometer Nondominant
1.5 SD
2 SD
%
PR
%
PR
%
PR
28.6*
10.7
25.0
1.8
0.7
1.6
5.4
5.4
8.9
0.8
0.8
1.4
3.6
3.6
1.8
1.6
1.6
0.8
26.8*
21.4
17.9
35.7***
16.1
10.7
1.7
1.3
1.1
2.2
1.0
0.7
3.6
3.6
10.7
5.4
10.7
16.1*
0.5
0.5
1.6
0.8
1.6
2.4
0.0
0.0
3.6
1.8
7.1*
3.6
—
—
1.6
0.8
3.2
1.6
17.9
21.4
19.6
10.9
19.6
1.1
1.3
1.2
0.7
1.2
7.1
8.9
5.4
3.6
0.0
1.1
1.4
0.8
0.5
—
3.6
7.1*
3.6
3.6
0.0
1.6
3.2
1.6
1.6
—
31.0***
35.1***
24.1
13.6
84.5***
67.8***
1.9
2.2
1.5
0.8
5.3
4.2
0.0
3.5
12.1
16.9*
0.0
0.0
—
0.5
1.8
2.5
—
—
0.0
1.8
8.6*
10.2***
0.0
0.0
—
0.8
3.6
4.3
Note. WAIS-R 5 Wechsler Adult Intelligence Scale-Revised.
*p , .05; **p , .01; ***p , .001.
The results of the tests of affect and mood are shown in Figures 1 to 3. The mean MMPI2 group profile (Figure 1) indicates that the validity scales are all within the normal range
while the participant group has clear scale elevations above T 5 70 for Hs, Hy and D. Sc
and Pt also are beyond the recommended cut-off of T 5 65. The mean scores for the BSI
(Figure 2) indicate elevations beyond T 5 70 for the Obsessive Compulsive scale as well
as for the overall Global Symptom Index. The POMS profile (Figure 3) indicates significant
elevations on the scales of Fatigue, Anger and Vigor.
For the entire sample, 64.4% (n 5 38) were diagnosed with Amnestic/Cognitive disturbance and 52.5% (31) with PTSD. Thirty-four percent (20) were diagnosed with both PTSD
and Amnestic/Cognitive disturbance, 18.6% (38) with PTSD only, and 30.5% (18) with
Cognitve/Amnestic disturbance only. Chi-square analyses revealed no significant differences
between litigants and nonlitigants for clinical diagnoses.
Correlational analysis of the MMPI-2 D and Pt scales demonstrate significant associations
at p , .01 with the BSI-Depression (r 5 0.47), BSI-Anxiety (r 5 0.51), BDI (r 5 0.49),
POMS-Depression (r 5 0.36) and POMS-Anxiety (r 5 0.63). The IES total score did not
correlate significantly with the MMPI-2 Pk scale (r 5 0.25), the IES-Intrusion scale (r 5
0.19) nor the IES-Avoidance scale (r 5 0.21).
For the PTSD-Pk scale, elevations beyond the recommended cut-off of T 5 65 were found
464
R. M. Bowler, C. Hartney, and L. H. Ngo
TABLE 4
Memory Assessment Scale
Memory Index scores
Short-term Memory
Verbal Memory
Visual Memory
Global Memory scale
Subtest scores (Age-corrected)
Verbal Span
Visual Span
List Acquisition
List Recall
Delayed List Recall
Immediate Prose Recall
Delayed Prose Recall
Immediate Names—Faces
Delayed Names—Faces
Visual Reproduction
Immediate Visual Recognition
Delayed Visual Recognition
Cued List Recall
Cued List Delayed Recall
List Recognition
M
SD
Range
n
92.14
93.40
94.75
93.05
15.21
14.05
16.94
15.66
53–127
53–125
53–126
53–125
58
58
57
57
8.59
7.97
9.07
8.78
8.29
8.47
8.55
7.26
7.50
8.61
8.25
8.67
10.17
10.59
11.79
3.01
2.82
3.04
3.20
2.87
3.07
3.65
3.18
3.02
3.15
3.13
3.44
1.70
1.46
0.49
1–15
3–15
1–15
1–13
2–14
1–14
1–15
1–14
2–14
1–16
1–14
2–19
4–12
6–12
10–12
58
58
58
58
58
58
58
58
58
57
57
57
58
58
58
Note. M 5 mean; SD 5 standard deviation.
TABLE 5
Percent Impaired for Memory Assessment Scale (MAS) and Risk of Impairment at 1,
1.5 and 2 Standard Deviations (SD) Below Mean of MAS Normative Sample
% Impaired (N 5 58), Chi-Square Significance, and
Prevalence Ratio (PR)
1 SD
Memory Index scores
Short-term Memory
Verbal Memory
Visual Memory
Global Memory Scale
Subtest scores
Verbal Span
Visual Span
List Acquisition
List Recall
Delayed List Recall
Immediate Prose Recall
Delayed Prose Recall
Immediate Names—Faces
Delayed Names—Faces
Visual Reproduction
Immediate Visual Recognition
Delayed Visual Recognition
Cued List Recall
Cued List Delayed Recall
*p , .05; **p , .01; ***p , .001.
1.5 SD
2 SD
%
PR
%
PR
%
PR
47.5***
42.4***
43.1***
43.1***
3.0
2.6
2.7
2.7
20.3***
8.5
17.2**
20.7***
3.1
1.3
2.6
3.1
3.4
5.1
10.3**
8.6*
1.5
2.3
4.6
3.8
32.2***
39.0***
27.1**
35.6***
47.5***
35.6***
44.1***
55.9***
50.8***
37.3***
37.3***
35.6***
10.2
5.1*
2.0
2.4
1.7
2.2
3.0
2.2
2.8
3.5
3.2
2.3
2.3
2.2
0.6
0.3
11.9
30.5***
13.6
23.7***
18.6**
20.3***
18.6**
28.8***
23.7***
11.9
20.3***
22.0***
3.4*
0.0
1.8
4.6
2.0
3.6
2.8
3.1
2.8
4.3
3.6
1.8
3.1
3.3
0.5
—
8.5*
3.4
10.2**
10.2**
6.8
15.3***
16.9***
23.7***
22.0***
11.9***
16.9***
11.9***
1.7
0.0
3.8
1.5
4.5
4.5
3.0
6.8
7.5
10.5
9.8
5.3
7.5
5.3
0.8
—
Amnestic Disturbance and PTSD After Chemical Release
465
TABLE 6
Means (M ) for All Subjects and Means and T-tests for Litigants versus Nonlitigants on Selected Test Scores
All Subjects
WAIS-R (HRB)
Full Scale Score
Verbal Score
Performance Score
Memory Indices
Short-term Memory
Verbal Memory
Visual Memory
Global Memory Scale
Stroop Color/Word Test
Word
Color
Color/Word
MMPI-2 Validity
Scales:
L
F
K
Rey
Litigants
Nonlitigants
M
SD
n
M
SD
n
M
SD
n
p-Value
47.1
49.3
47.5
11.0
8.6
10.4
56
56
56
46.2
48.3
46.4
11.3
8.3
10.5
47
47
47
51.8
54.9
53.1
7.7
8.8
8.3
9
9
9
0.164
0.033
0.077
91.8
93.1
94.0
92.5
15.3
14.1
17.7
16.0
59
59
58
58
91.0
92.4
93.4
91.7
14.8
15.0
17.8
16.5
50
50
49
49
96.6
97.0
97.4
97.1
17.9
6.9
17.6
12.9
9
9
9
9
0.317
0.372
0.533
0.356
41.9
39.2
39.1
8.2
8.5
9.4
59
59
59
41.1
39.1
38.9
8.0
9.0
9.8
50
50
50
46.6
39.7
40.0
7.9
5.7
7.1
9
9
9
0.063
0.851
0.744
56.5
60.9
47.4
13.3
10.3
13.0
9.3
2.3
58
58
58
57
56.7
61.9
47.8
13.3
10.4
12.9
9.5
2.3
49
49
49
48
55.2
55.9
45.2
13.0
10.3
12.6
8.1
2.8
9
9
9
9
0.698
0.206
0.448
0.698
SD 5 standard deviation; WAIS-R 5 Wechsler Adult Inventory Scale—Revised; HRB 5 Halstead-Reitan Battery;
MMPI-2 5 Minnesota Multiphasic Personality Inventory-2.
FIGURE 1. Mean Minnesota Multiphasic Personality Inventory (MMPI) T-scores for all participants.
466
R. M. Bowler, C. Hartney, and L. H. Ngo
FIGURE 2. Mean Brief Symptom Inventory (BSI) T-scores for all participants.
FIGURE 3. Mean Profile of Mood States (POMS) T-scores for all participants.
Amnestic Disturbance and PTSD After Chemical Release
467
for 35.6% (21) of the sample. Of the 30 patients diagnosed with PTSD, 50% (15) had elevations of 65 or higher on the PTSD-Pk scale. Conversely, of 21 patients with elevations of
65 or higher on the PTSD-Pk scale, 71.4% (15) were diagnosed with PTSD. A chi-square
of PTSD-Pk (as a binary variable: elevated beyond T 5 65 or not) and a diagnosis of PTSD
(as a binary variable: diagnosed with PTSD or not) showed these differences to be significant
(5.12, p 5 .0237).
Correlational analysis of toxic symptoms and test scores indicate a relative absence of
significant correlations for the cognitive function tests and multiple significant correlations
for the mood tests. No significant correlations were found between individual test scores
and diagnoses of PTSD or Amnestic/Cognitive disturbance (as binary variables, present or
absent).
DISCUSSION
After the Catacarb release, the participants reported greater physical symptoms and illnesseses (skin rashes, respiratory, visual, dermatological, headaches, and gastrointestinal), which
can be attributed to the toxic action of the chemicals to which they were exposed. They also
were found to have significantly greater than expected prevalence of Amnestic/Cognitive
disturbance (64%), PTSD (54%), and dysphoric mood (98%). According to their clinical
health histories, they had been functioning adequately prior to the Catacarb release (those
who had prior disease were excluded in this study).
Toxic/organic Versus Functional Etiology
The types of physical symptoms and new onset illnesses following the chemical exposure
are strongly suggestive of a physical/organic etiology. Prior studies of Catacarb health effects
are supportive of this interpretation (Bowler, 1997). The onset of PTSD may be a functional
reaction to the stressor of the exposure while the dysphoric mood may be both a functional
reaction and an organic effect from the exposure. Haley, Kurt, and Hom (1997), in their
study of the Gulf War syndrome, postulate a similar hypothesis of mood disturbance resulting
from health concerns over somatic symptoms from chemical exposure and not from traumatic
stress alone.
The Amnestic/Cognitive disturbance found in the present study appears to be of both
organic and functional etiology. Both those who were diagnosed with either Amnestic/Cognitive disturbance exclusively or PTSD exclusively, showed deficits in neuropsychological
function. This suggests that the deficits were caused both by the Catacarb toxicity directly
and the stress ensuing from an acute chemical exposure. It is, however, not possible to sort out
the degree of organic versus functional etiology because quantitative measures of chemical
exposure were not available.
Similar neuropsychological deficits in concentration, memory, disordered information processing, and mood can be attributed to neurotoxic exposures and to PTSD. Generally, neurotoxins effect the brain in a diffuse manner, and only certain neurotoxins, such as lead or
other heavy metals, are known to produce specific disturbance, such as visual and motor
impairment.
Measures of Mood Dysfunction and PTSD Useful in Chemical Accidents
The results of tests of mood and affect in this group consistently indicate they have mood
disturbance and PTSD symptoms. All participants reported greater disturbance than normal
468
R. M. Bowler, C. Hartney, and L. H. Ngo
expectation on the BSI, BDI, POMS, and IES. The MMPI-2 scale scores further indicate
that 98% of the sample had elevations beyond T 5 65 (the manuals recommended cut-off
for psychopathology) on at least one clinical scale.
Although the MMPI-2 is highly useful in individual diagnostic studies, the shorter POMS,
BSI, and BDI, when used for group research purposes in conjunction with the IES, provide
sufficient data to document the level of dysfunction. Inspection of correlations between
MMPI-2 scales and the depression and anxiety scales of the less time consuming POMS,
BSI, and BDI indicate a strong relationship.
Anger and hostility, as well as symptoms of autonomic hyperarousal, are common components of PTSD and are specified in the DSM-IV listed criteria for the diagnosis of PTSD.
Significant Anger and Hostility score elevations on the POMS and BSI (even when compared
to psychiatric outpatients) were obtained by the participants. Anger appears to be more directly measured by the POMS Anger and BSI Hostility scales, than by the MMPI-2 Pd scale.
The group scored higher on the IES than the mean of the Horowitz et al. (1979) stress
clinic patients. Use of the IES in cases of chemical accidents and other disasters is justified
as a direct measure of the impact of the traumatic event (Horowitz, 1986). The IES also
provides quantitative summary scores for intrusion and avoidance, two mechanisms common
in PTSD. The content of the IES includes most of the symptom criteria in DSM-IV required
for the diagnosis of PTSD, which makes it a useful adjunct in the clinical diagnosis of PTSD.
The IES is consequently more specific in assessing response to trauma from chemical accidents (Bowler et al., 1994; Green, 1991) than the MMPI Pk scale, which appears to be less
a measure specific to PTSD and more a measure of generalized affective distress, which is
indicated by multiple strong correlations of the MMPI Pk scale and the mood subtests (excepting the IES).
Usefulness of Heaton and Other Test Norms as Comparisons
Heaton’s comprehensive normative database with corrections for age, gender, and education facilitates statistical comparison in the absence of a control group (Heaton, 1992). The
use of the HRB norms with scores of the WAIS-R, Trail Making, and motor tests permits
the computation of empirically derived impairment ratings, which support and augment judgments made primarily from clinical history.
HRN norm comparisons indicated that these participants had problems with sustaining
concentration, information processing, verbal fluency and cognitive flexibility. However, it
appears judicious to use a cut-off score of one and one half or two standard deviations below
the mean in order to avoid overpathologizing.
Evaluation of Malingering and Best Performance
Clinical observation by the examiners suggested the participants were giving their best
performance. This was supported by the consistency of tests of similar function and by scores
on the Rey 15-Item Visual Memory test and the validity scales of the MMPI-2. Only two
persons obtained a total score of 7 on the Rey, one with less than high school education and
the other with limited vocational training. The remainder of the participants all scored above
9 on this test.
PTSD, Amnestic Disturbance, and Chemical Accidents
An association between Amnestic/Cognitive disturbance (memory impairment plus disordered information processing) and PTSD has been previously identified (Kolb & Mutiliplassi,
Amnestic Disturbance and PTSD After Chemical Release
469
1982; McFarlane et al., 1994; Van der Kolk, 1994). In studies of prior chemical exposures
(Bowler et al., 1997; Bowler, Huel et al., 1996; Bowler, Mergler, Bowler, & Rauch, 1992;
Bowler, Mergler, Harrison, Rauch, & Cone, 1991; Bowler, Mergler, Huel, & Cone, 1996;
Bowler & Schwarzer, 1991; Freed et al., 1996) and other technological disasters (Baum,
Fleming, & Singer, 1982; Baum, Gatchell, & Schaeffer, 1983; Green & Solomon, 1995)
similar findings have been shown, but without the further empirical support of the extensive
neuropsychological test results obtained in this study.
Social/Psychological Implications of Participants Dysfunction
Negative reactions to the trauma of an unforeseen and uncontrollable chemical accident
appear to have caused significant disability in individuals who incur such traumas. Chemical
accidents and technological accidents already have been shown to cause longer-lasting impairment than natural disasters (Baum, Fleming, & Singer, 1982).
Measures of the participants dysphoric mood and dysfunctional memory and information
processing support their complaints of major disruption in their everyday lives. In the absence
of significant psychiatric histories prior to the chemical release, an association of PTSD with
the Catacarb exposure is strongly indicated.
Comorbidity effects have been shown to be associated with significantly greater disturbance in function in cumulative trauma patients with elevated clinical scales on the MMPI2 (Somer, Keinan, & Carmil, 1996; Weyerman, Norris, & Hyer, 1996) It is likely that those
participants who have residual PTSD will have greater reactivity to new chemical events.
This makes apparent the need for immediate intervention in prevention of new onset and the
worsening of PTSD in future chemical exposures. Participants in this study who had PTSD
and dysphoric mood symptomatology were referred for individual and group psychotherapy,
cognitive retraining and biofeedback, but outcome data are not yet available.
The issue of cumulative effects of trauma is also of concern. In fact, several later chemical
alerts in the town studied resulted in a re-enactment of the trauma with residents reacting
with a flare-up of PTSD symptoms.
CONCLUSION
This study shows that a large group of refinery neighbors developed physical symptoms
consistent with the chemical exposure, PTSD in reaction to the event of exposure, and
Amnestic/Cognitive disturbance, from both an organic and functional etiology.
With increasing chemical manufacturing, more accidents are likely to occur. Neuropsychologists will increasingly be called upon to evaluate the functional deficits of exposed
persons and will be asked to make attributions of the cause of deficits in such populations.
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