Vol.2, No.2, 90-96 (2010)
doi: 10.4236/health.2010.22015
Copyright © 2010 Openly accessible at http://www.scirp.org/journal/HEALTH/
Subgroups of chronic fatigue syndrome based on
psychiatric disorder onset and current psychiatric status
Molly M. Brown, Carly Kaplan, Leonard A. Jason, Christopher B. Keys
Center for Community Research, DePaul University, Chicago, USA; mbrown59@depaul.edu
Received 22 October 2009; revised 2 December 2009; accepted 4 December 2009.
Few studies have examined the effects of psy-
chiatric disorders occurring over a long dura-
tion among patients with chronic fatigue syn-
drome (CFS). The role of premorbid and current
psychiatric disorders in impairment was ex-
plored with a sample of 113 participants with
CFS. Subgroups were created based on past
and current psychiatric status including those
whose psychiatric history was premorbid and
current, postmorbid and current, past but not
current, and those with no lifetime diagnosis.
Results from a one-way MANOVA revealed that
patients with a premorbid and current psychiat-
ric disorder reported significantly higher pain
severity, more somatic symptoms, poorer sleep
quality, and poorer quality of life than those with
no psychiatric history. Levels of fatigue and
physical functioning among patients with CFS
were unrelated to the four subgroups in this
study. Although those with a premorbid and
current psychiatric disorder were differentiated
from those with no psychiatric history on some
markers of impairment, the sample as a whole
had severe fatigue-related impairment, which is
the cardinal symptom of CFS. Implications for
research are discussed.
Keywords: Chronic Fatigue Syndrome; Psychiatric
Comorbidity; Subgroups; Impairment
Chronic fatigue syndrome (CFS) is a chronic, debilitat-
ing illness that remains poorly understood. Some pa-
tients with CFS experience psychiatric symptoms, but
the role of these symptoms in the development, mainte-
nance, and severity of the illness is unclear. Several
studies have found high rates of psychiatric comorbidity
among patients with CFS in the range of 45% to 50%, [1,
2] and up to 82% for a lifetime psychiatric diagnosis, [3]
exceeding rates in the general population.
A number of studies have examined the role of co-
morbid psychiatric issues in the course of CFS. While
one study found that patients with CFS who had a co-
morbid psychiatric diagnosis had significantly more se-
vere fatigue than those without a psychiatric disorder, [4]
most research has not found that psychiatric comorbidity
increases impairment in CFS. Studies comparing pa-
tients with and without psychiatric comorbidity have
found no differences in impairment in sleep, [5] neuro-
cognitive functioning, [6,8] physical functioning, [9,11]
fatigue severity, [5] and widespread pain. [11] These
results suggest that psychiatric comorbidity is not related
to higher illness severity in this population.
Due to the unexpected lack of evidence for a relation-
ship between psychiatric comorbidity and illness sever-
ity in CFS, it is perhaps more important to explore
long-term psychiatric status in CFS, as opposed to pre-
sent psychiatric comorbidity only. Individuals with psy-
chiatric illness early in life may be more likely to de-
velop CFS later in life, [12] indicating that a subgroup of
patients with CFS may have a long-term history of psy-
chiatric disorder beginning prior to the onset of CFS. It
has been hypothesized that an onset of psychiatric dis-
order predating CFS may be indicative of a long history
of poor coping skills, leading to increased impairment.
Tiersky, Matheis, DeLuca, Lange, and Natelson [13]
developed psychiatric subgroups based upon whether the
onset of the psychiatric disorder was before (premorbid)
or after (postmorbid) CFS onset. They found that pa-
tients with CFS with a premorbid and current psychiatric
diagnosis performed significantly worse on neuropsy-
chological tests than patients with no history of psychi-
atric disorder and healthy controls. However, they did
not find increased physical impairment in this subgroup.
Tiersky et al. developed more specific psychiatric sub-
groups of patients with CFS compared to previous stud-
ies. Nonetheless, their study did not include patients who
had a psychiatric disorder in the past but did not cur-
M. M. Brown et al. / HEALTH 2 (2010) 90-96
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rently meet criteria for the disorder. In other words, it
may also be important to examine CFS severity for peo-
ple who have recovered from a past psychiatric disorder,
as remission from a psychiatric illness is associated with
increased self-efficacy [14] and may be indicative of
adaptive coping leading to better functioning. Further,
the authors did not explore some key features of CFS
severity such as sleep quality, pain severity, and diversity
of symptoms.
The present study examined four groups of patients
with CFS: those with a premorbid and current psychiat-
ric diagnosis, those with a postmorbid and current psy-
chiatric diagnosis, those with a past (either premorbid or
postmorbid) but no current psychiatric diagnosis, and
those with no history of psychiatric diagnosis. We hy-
pothesized that patients with a premorbid and current
psychiatric disorder would have increased physical and
psychiatric impairment compared to patients with a
postmorbid and current psychiatric diagnosis, those with
a past but not current psychiatric disorder, and those
with no history of psychiatric disorder.
2.1. Participants
The present investigation used baseline data derived
from a larger longitudinal study of non-pharmacological
treatment interventions for CFS. [15] Participants were
recruited from physician referrals, media advertisements,
and CFS support groups.
Participants were at least 18 years of age, not pregnant,
able to read and speak English, and considered to be
physically capable of attending scheduled appointments.
Participants were included if they met the Fukuda et al.
[16] criteria for CFS (i.e., six or more months of persis-
tent fatigue accompanied by four of the following eight
symptoms: tender lymph nodes, sore throat, new or dif-
ferent headaches, muscle pain, joint pain, post-exertional
malaise, unrefreshing sleep, and memory or concentra-
tion difficulties). Medical and psychiatric examinations
were provided to rule out exclusionary medical or psy-
chiatric diagnoses according to the Fukuda et al. criteria.
In addition, participants in the current study must have
provided self-reported date of onset for CFS and psychi-
atric diagnoses. A total of 113 participants were included
in the present investigation. The DePaul University In-
stitutional Review Board approved all procedures. All
participants provided written informed consent.
2.2. Materials
2.2.1. CFS Questionnaire
The CFS Questionnaire was used to collect date of CFS
onset, demographic, health status, medication usage, and
symptom data. This screening scale has demonstrated
adequate validity and inter-rater and test-retest reliability.
Jason, Corradi, and Torres-Harding [19] explored 22
theoretically derived symptoms of CFS from the CFS
Questionnaire for diagnostic importance. The authors
found that these 22 symptoms are common among pa-
tients with CFS and are indicators of symptom clusters,
including: neurocognitive (e.g., slowness of thought),
vascular (e.g., dizzy after standing), inflammatory (e.g.,
allergies), muscle/joint (e.g., muscle pain), infectious
(e.g., flu-like symptoms), and sleep/post-exertional (e.g.,
unrefreshing sleep) symptoms. This study utilized these
22 symptoms to measure total somatic complaints
among participants. The total number of currently pre-
sent symptoms endorsed by participants was used to
determine the breadth of current symptoms experienced
by participants.
2.2.2. Structured Clinical Interview for DSM-IV
The SCID [20] was administered in order to establish
Axis I psychiatric diagnoses. While a coding scheme is
included in the instrument, the SCID allowed for clinical
judgment in the assignment of symptoms to psychiatric
or medical categories, a crucial distinction in the as-
sessment of symptoms that overlap between CFS and
psychiatric disorders, e.g., fatigue, concentration diffi-
culty, and sleep disturbance. [21] A psychodiagnostic
study [22] validated the use of the SCID in a sample of
CFS patients. Through questioning about psychiatric
symptom onset, an approximate date of psychiatric dis-
order onset is determined on the SCID.
2.2.3. Medical Outcomes Study-Short Form-36
The SF-36, was used to measure self-reported functional
status related to health. [23] The full measure included
36 self-report items that identified eight health concepts,
or scales. This study used the Physical Functioning scale
to measure overall disability. Higher scores indicated
better health. Test construction studies for the SF-36
[24,25] found adequate internal consistency and dis-
criminant validity across the eight scales of this measure.
2.2.4. Fatigue Severity Scale (FSS)
The FSS [26] was used to measure fatigue. This scale
included 9 items rated on 7-point scales, and higher
scores indicated more severe behavioral consequences of
fatigue. Previous findings have demonstrated the utility
of the FSS to discriminate between individuals with CFS,
multiple sclerosis, and primary depression. [27] Within a
CFS-like group, the FSS was found to be closely associ-
ated with severity ratings for the eight Fukuda et al. [16]
CFS symptoms as well as with functional outcomes re-
lated to fatigue. [28]
M. M. Brown et al. / HEALTH 2 (2010) 90-96
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2.2.5. Brief Pain Inventory (BPI)
The BPI [29] was administered to measure the intensity
of pain (pain severity) and the interference of pain in the
patient's life (pain interference). This measure consisted
of 14 questions with scores on each scale ranging from 0
to 10. Higher scores indicated more pain. This measure
exhibited adequate levels of reliability to assess pain in
non-cancer samples, with alpha coefficients of .70 and
above. [29] It also evidenced good concurrent validity
with other generic pain measures. [30]
2.2.6. Pittsburgh Sleep Quality Index (PSQI)
The PSQI was a self-report measure developed to assess
sleep quality in psychiatric research. [31] This index
measured sleep disruptions and sleep quality. There were
19 questions (on 0-3 scale) which generated seven
“component” scores: subjective sleep quality, sleep la-
tency, sleep duration, habitual sleep efficiency, sleep
disturbances, use of sleeping medication, and daytime
dysfunction. The sum of scores for these seven compo-
nents yielded one global score, which ranged from 0 to
21. Higher scores indicated worse sleep quality. The
global scale demonstrated adequate internal consistency,
test-retest reliability, and discriminant and concurrent
validity. [31]
2.2.7. Quality of Life Scale (QLS)
The QLS measured satisfaction with different life activi-
ties for individuals with various chronic illnesses. [32]
The scale consisted of 16 items answered on a Likert-
type 1 to 7 scale asking how satisfied individuals are
with each item. Higher scores indicated more overall life
satisfaction. This scale demonstrated high test-retest
reliability, convergent, discriminant, and construct valid-
ity among individuals with various stable chronic ill-
nesses. [32]
2.3. Procedure
Once study eligibility criteria were met and no exclu-
sionary illnesses were found based on the medical ex-
amination or SCID findings, participants completed
self-report measures. The 113 participants were then
divided into four psychiatric subgroups based on onset
of psychiatric disorder in relation to CFS onset and cur-
rent psychiatric status. In order to determine whether
participants had a psychiatric disorder that predated the
onset of CFS, the date of psychiatric disorder onset de-
rived from the SCID was compared with self-reported
date of CFS onset from the CFS Questionnaire. Specifi-
cally, participants with a current psychiatric disorder
who reported having a psychiatric disorder at any point
in their life prior to developing CFS were considered to
have a premorbid and current psychiatric disorder (n =
32; 28.3%). Those with a current psychiatric diagnosis
and a history of psychiatric disorder that never predated
CFS onset were considered to have a postmorbid and
current disorder (n = 12; 10.6%). Those with a history of
psychiatric disorder who do not currently meet criteria
for a psychiatric disorder comprised a third subgroup
referred to past but not current psychiatric disorder (n =
28; 24.8%). Finally, patients with no lifetime psychiatric
diagnosis were placed into a fourth subgroup (n = 41;
2.4. Statistical Analyses
Pearson chi-square analyses and one-way analysis of
variance (ANOVA) were used to examine differences
among the four psychiatric groups with regard to demo-
graphic variables. Fisher’s Exact Tests were computed
using SAS Proc Freq to compare the three groups with a
history of psychiatric disorders on DSM-IV diagnostic
categories. A one-way ANOVA was used to compare
total number of lifetime psychiatric diagnoses between
the three groups.
One-way multivariate analysis of variance (MAN-
OVA) was used to test the primary hypotheses of this
study with psychiatric group (premorbid and current,
postmorbid and current, past but not current, and no life-
time psychiatric disorder) as the independent variable.
The use of MANOVA reduced the likelihood of Type I
error when making comparisons of multiple related de-
pendent variables. [33] Upon examination of the correla-
tion matrix of the outcome variables used in this study,
all outcome variables were moderately correlated (r .3)
with at least two other outcomes, indicating that
MANOVA would be appropriate. Wilks’ Lambda F ap-
proximation was used for interpretation of the multivari-
ate test, and Bonferroni tests were used for post hoc
3.1. Demographic Characteristics
In regards to demographic characteristics, 83.2% of par-
ticipants were female. The average age was 43.8 years.
Regarding ethnicity, 87.6% were White, 4.4% were Af-
rican American, 4.4% were Latino, and 3.5% were Asian
American. As for marital status, 48.7% were married or
living with a partner, 32.7% were single, and 17.7%
were divorced or separated. In terms of work status,
40.7% were working or full time students and 59.3%
were part-time students, retired, unemployed or on dis-
ability. With regards to education, 46.9% had earned a
standard college degree, 22.1% had a graduate or pro-
fessional degree, 21.2% had partial college, and 9.7%
had a high school/GED degree or less. No significant
M. M. Brown et al. / HEALTH 2 (2010) 90-96
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Table 1. Lifetime Psychiatric Diagnoses for Psychiatric Subgroups.
Premorbid and current
(n = 32)
Postmorbid and current
(n = 12)
Past but not current
(n = 28)
Any Mood Disorder 59.4% 58.3% 50.0%
Major Depressive Disorder 50.0% 58.3% 46.4%
Dysthymic Disorder 18.8% 0.0% 0.0% *
Other Mood Disorder 0.0% 0.0% 3.6%
Any Anxiety Disorder 56.3% 33.3% 46.4%
Generalized Anxiety Disorder 9.4% 8.3% 3.6%
Panic Disorder (with or without Agoraphobia) 25.0% 16.7% 17.9%
Posttraumatic Stress Disorder 37.5% 0.0% 10.7% **
Other Anxiety Disorder 6.3% 8.3% 10.7%
Adjustment Disorder 21.9% 33.3% 7.1%
Other 25.0% 0.0% 14.3%
Total Lifetime Psychiatric Disorders (Mean) 1.97 a, b 1.25 a 1.25 b ***
Notes: *p < .05, **p < .01, ***p < .001; Similar letters across rows indicate significant difference
differen ce s were found among the four groups in terms
of demographic variables.
3.2. Diagnostic Outcomes
Total lifetime psychiatric diagnoses and rates of different
psychiatric diagnostic categories were compared for the
three groups with a history of psychiatric disorder (Ta-
ble 1). Fisher’s Exact Tests revealed that the three groups
did not differ in terms of lifetime presence of anxiety or
mood disorders. When comparing differences among the
three psychiatric groups for specific psychiatric diagno-
ses, a significant difference was revealed for lifetime
dysthymic disorder (p = .02), and the premorbid and
current psychiatric group had the highest rate (18.8%)
compared to the other two groups with rates of 0%. A
significant difference between groups was also found for
lifetime posttraumatic stress disorder (p = .01). The
premorbid and current group had the highest rate of
posttraumatic stress disorder (37.5%), the past but not
current group had the second highest rate (10.7%), and
no participants from the postmorbid and current group
met criteria during their lifetime.
A one-way ANOVA revealed that the groups signifi-
cantly differed on total number of lifetime psychiatric
diagnoses, F(2, 69) = 9.19, p < .001. Bonferroni post hoc
analyses indicated that the premorbid and current psy-
chiatric group had significantly more lifetime psychiatric
diagnoses than both the postmorbid and current group (p
= .01), and the past but not current group (p = .003).
3.3. Main Outcomes
Sixteen participants had missing data for one or more of
the self-report outcome measures and were therefore
excluded, which left a total of 97 participants for analy-
sis of main outcomes (See Table 2). Results from the
one-way MANOVA revealed a significant overall mul-
tivariate effect for psychiatric group on the combined
DVs, Wilks’ Lambda = .68, p = .03.
Descriptive statistics for outcomes are reported in Ta-
ble 2. Upon examination of univariate effects, signifi-
cant differences were found for pain severity [F(3, 93) =
3.08, p = .03], pain interference [F(3, 93) = 3.27, p
= .03], total somatic symptoms [F(3, 93) = 3.86, p = .01],
sleep quality [F(3, 93) = 4.59, p = .01], and quality of
life [F(3, 93) = 3.31, p = .02]. No significant univariate
effects were found for fatigue severity or physical func-
tioning. Bonferroni post hoc tests revealed the premorbid
and current group scored significantly worse than the no
lifetime diagnosis group for pain severity (p = .02), pain
interference (p = .02), total somatic symptoms (p = .03),
sleep quality (p = .003), and quality of life (p = .02).
Patients with CFS with a premorbid and current psychi-
atric disorder reported significantly higher pain severity
and interference, more somatic symptoms, poorer sleep
quality, and poorer quality of life than those who have
never been diagnosed with a psychiatric disorder. No
ignificant differences in impairment were found for s
M. M. Brown et al. / HEALTH 2 (2010) 90-96
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Table 2. Means (and Standard Deviations) for Psychiatric Subgroups on Outcome Measures.
Premorbid and current
(n = 29)
Postmorbid and current
(n = 11)
Past but not current
(n = 22)
No lifetime diagnosis
(n = 35) Sig.
Physical Functioning1 38.72 (24.00) 40.91 (28.88) 48.64 (18.01) 46.57 (22.68)
Fatigue Severity2 6.19 (1.01) 6.29 (0.64) 6.16 (0.71) 5.98 (0.69)
Pain Severity2 4.94 (2.19) a 3.98 (2.39) 4.30 (1.58) 3.33 (2.31) a *
Pain Interference2 5.33 (3.15) a 4.81 (3.25) 4.40 (2.01) 3.24 (2.56) a *
Somatic Symptoms2 16.21 (3.56) a 17.00 (3.23) 15.36 (4.67) 13.37 (3.99) a **
Sleep Quality2 9.55 (1.77) a 8.36 (3.29) 8.05 (2.28) 7.49 (2.23) a **
Quality of Life1 59.48 (15.87) a 69.91 (18.11) 65.68 (12.42) 71.03 (15.16) a *
Notes: Similar letters across rows indicate significant difference; 1Higher numbers are better; 2Lower numbers are better; *p < .05, **p < .01
participants in the other two psychiatric history groups
compared to the no lifetime diagnosis group. These re-
sults in combination with two of Tiersky et al.’s [13]
neuropsychological findings suggest that patients with
CFS who have a premorbid and current psychiatric dis-
order have significantly more impairment than those
with no psychiatric history, while patients with other
categorizations of psychiatric history are not differenti-
ated from patients without a psychiatric history in terms
of impairment. However, the postmorbid and current
psychiatric group did, in fact, demonstrate the highest
level of fatigue severity and the most somatic symptoms
compared to the other three groups, but significant dif-
ferences were not revealed due to the small sample size
for this group. Although patients with a premorbid and
current psychiatric history were found to represent a
subset of the CFS population that experiences particu-
larly severe illness symptomatology, patients with a
postmorbid and current diagnosis may also have in-
creased illness severity.
Despite findings of increased impairment on some
outcomes for those who had premorbid and current psy-
chiatric diagnoses, no differences were found between
groups for physical functioning or fatigue severity.
Moreover, it is evident from this study that patients with
and without psychiatric disorders exhibit notably high
levels of fatigue and disability. These findings are con-
sistent with previous research demonstrating that psy-
chiatric comorbidity does not differentiate patients in
terms of physical functioning [9] or fatigue severity. [5]
Of note is that fatigue is the cardinal symptom of CFS,
and findings from this and previous studies suggest that
this symptom is present at a severe level regardless of
psychiatric status.
In terms of severity of psychiatric functioning among
patients with CFS, our prediction that the premorbid and
current psychiatric group would evidence the most psy-
chiatric dysfunction as defined by more lifetime psychi-
atric diagnoses was confirmed and was consistent with
prior research. [13] This finding suggests that patients
who have had ongoing mental health issues beginning
prior to CFS onset tend to have more pervasive emo-
tional problems. High levels of psychiatric impairment
over time, in turn, may be related to increased ill-
ness-related impairment compared to those with a
shorter-term history of psychiatric disorder.
The premorbid and current group had, on average, a
total of 16.21 somatic symptoms compared to the no
history group which had an average of 13.37 symptoms.
This greater number of somatic symptoms suggests that
the clinical presentation of patients with longstanding
mental health issues is more complex than those without
a psychiatric history. Exclusion of premorbid psychiatric
disorder in CFS samples has been used to reduce sample
heterogeneity in some studies. [34] Results from this
study provide support for sample selection strategies that
take into consideration premorbid psychiatric function-
ing, as long-term psychiatric status adds complexity to
the illness symptomatology.
Several limitations can be noted for the present inves-
tigation. The use of self-reported onsets of psychiatric
disorder and CFS to determine psychiatric subgroups
may be problematic, as both are vulnerable to recall bias.
[35,36] Further, research has shown that those with a
gradual CFS onset were more likely to report long-term
depressive symptomatology gradually leading to the on-
set of the illness. [37] Thus, the self-reported onset of
CFS in the present study may not have been accurate for
all participants, particularly those who also had a gradual
illness onset. Finally, differences between groups may
not have been revealed in the analysis due to small sam-
ple sizes and low power. Future research with a larger
sample size is needed to more fully explore functioning
among patients with a postmorbid and current psychiat-
ric diagnosis.
This study added to previous research demonstrating
that neuropsychological functioning is impacted based
on premorbid and current psychiatric status. [13] The
M. M. Brown et al. / HEALTH 2 (2010) 90-96
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findings indicated that long term psychiatric dysfunction
increased impairment on several key indicators of CFS
severity: sleep difficulties, pain, and wide ranging so-
matic symptoms. However, the sample as a whole had
high levels of fatigue and physical impairment which
were unrelated to the four subtypes, suggesting that even
patients without a psychiatric history suffer from severe
disability. Since the premorbid and current psychiatric
history group also evidenced the most psychiatric dys-
function, treatment targeting mental health issues may
help reduce symptom severity for this particular sub-
group of patients. Past research suggests that examining
current psychiatric status may not differentiate patient in
terms of symptomatology. Based on the findings from
this study, future research exploring the role of psychiat-
ric functioning in CFS should examine psychiatric sub-
groups based on the onset and current status of the psy-
chiatric disorder.
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