Irritable Edward
Bowel
A. Walker,
Syndrome
M.D.,
Peter
P. Roy-Byrne,
Psychiatric illnesses such as mood, anxiety, and somatization disorders share many common features with irritable bowel syndrome. The authors review recent developments in the definition of irritable bowel syndrome and its relationship to psychiatric illness, discuss the diagnostic validity of irritable bowel syndrome from several perspectives, and offer a pathophysiological model of irritable bowel syndrome that integrates many of the biological and psychosocial fi ndings of earlier studies. Psychiatric evaluation appears to be an important factor in the diagnosis and treatment of patients with irritable bowel syndrome. (Am J Psychiatry 1990; 147:565-572)
I
rritable
bowel
trointestinal
syndrome disorder
its
definition
and
its
status
as
of
J.
M.D.,
and
syndrome 1) Irritable
and psychiatric illness could be rebowel syndrome could be a precursor disorders. This view holds that psychi-
psychiatric
atnic symptoms chronic physical
Wayne
develop disease
Katon,
secondary to the (a “somatopsychic”
Irritable bowel syndrome could or forme fruste of psychiatric
2)
non
chosomatic” idea
This
when
symptoms
view
stress of a model).
be an epiphenomedisorders (a “psy-
is compatible
with
the
those of irritable bowel synare common in the general population and, amplified by psychiatric illness, reach the status
drome of
model).
that
M.D.
disease
a
like
or disorder
(15).
common
gas-
by primary
care
psychiatric
physicians and gastroenterologists: prevalence figures range from 13% to 52% of new referrals to gastrointestinal clinics (1, 2). Despite the high prevalence of this disorder, however, there is incomplete agreement on
bowel lated.
Illness
further evaluate the relationship of irritable syndrome and psychiatric illness, we will exfour questions: 1) What is known about the definition and diagnostic validity of irritable bowel syndrome? 2) How are irritable bowel syndrome and
is the most encountered
and Psychiatric
a valid
To bowel plore
symptoms
iological
model
for
related? irritable
3) Is there bowel
a pathophys-
syndrome
that
in-
cludes a neurobiological component? and 4) What is the role of the psychiatrist in the evaluation and treatment of patients with irritable bowel syndrome?
diagnostic
entity.
One
of the more
striking
features
of this
syndrome
is
the frequent finding of associated psychiatric illness, especially mood, anxiety, and somatization disorders. Studies
have
suggested
that
54%-100%
of
patients
with irritable bowel syndrome may have associated psychiatric illness (3-8). Although the psychological characteristics
irritable
and
bowel
psychiatric
syndrome
viewed (9-13), the been well established. The clarification
Methodological dromes such demonstrated delimitation
atric
There
have
nature of
as the from
been
has
re-
two
possible
J
Psychiatry
147:5,
May
1990
syndrome
sion, cient
syn-
nosis
names,
SYNDROME?
each
avoid
the
trap
by exclusion,
nate
of heterogeneity
Manning
ther
diagnostic
with
irritable
with
organic
disease.
refined
models
by Thompson
bowel and
in diag-
the
to discrimi-
syndrome criteria
Heaton
suffi-
suggested
criteria These
of
bowel exclu-
lack
inherent
et al. (16)
patients
patients
changing
to patients whose symptoms for an organic etiology.
of operationalized
use
reflecting
psychological etiology (9). Irritable has been considered a diagnosis of
assigned evidence
To
(17),
from were
fur-
Drossman
al. (15), Whitehead and Schuster (18), and, most recently, by an international congress on gastroenterology in Rome (Drossman, 1988, personal communication). The congress defined irritable bowel syndrome as follows:
et
ways
that
irritable
Received April 25, 1989; revisions received July 12 and Sept. 6, 1989; accepted Sept. 18, 1989. From the Department of Psychiatry and Behavioral Sciences, Division of Consultation-Liaison, University of Washington. Address reprint requests to Dr. Walker, Department of Psychiatry and Behavioral Sciences, Division of Consultation-Liaison, University of Washington, Seattle, WA 98195. Copyright © 1990 American Psychiatric Association.
Am
and
organic
not
populations.
at least
BOWEL
It is not easy to define what irritable bowel syndrome is but easy to say what it is not. Since its initial description by Powell in 1820, it has been described by
is important.
heterogeneous
IS IRRITABLE
30 different
with
extensively
association
relationship
of other
of patients
premenstrual syndrome (14) have importance of careful definition and other disorders, particularly psychito avoid the problems inherent in
heterogeneous
are
of this
this
critiques
conditions,
studying
illnesses
WHAT
Continuous
or
1. Abdominal ated
with
recurrent
pain, change
symptoms
relieved in frequency
of:
with
defecation or
consistency
or associof
stool,
and/or
565
IRRITABLE
2.
BOWEL
SYNDROME
Disturbed
defecation
a)
altered
stool
frequency,
b)
altered
stool
form
c)
altered
stool
passage
ing
d)
incomplete
passage
usually
with
3.
Bloating
Noting patients
of
the with
(two
or
(hard
more
of):
patients
or loose/watery),
(straining
or
urgency,
feel-
evacuation),
or
feeling
high irritable
gested
abdominal
the symptoms parents and recurrent abdominal
prevalence bowel
of emotional syndrome,
distress Whitehead
in et
al. (18, 19) suggested that psychological criteria be incorporated into the definition. Additionally, proposed the need for two distinct sets of criteria,
also they one for research and another for clinical use. Research diagnostic criteria would select a specific, narrowly defined, homogeneous population for epidemiologic and treatment outcome studies, but a more sensitive, broad set of clinical criteria could be used for treatment in outpatient clinics. Although irritable bowel syndrome was first recognized as a disorder of the colon, some gastroenterologists feel that because the motility and functioning of various parts of the gastrointestinal tract are more alike than dissimilar, irritable bowel syndrome may represent a continuum of similar gastrointestinal diagnoses with symptoms that are site-specific depending on the level of involvement (20-22). Thus, patients with esophageal symptoms, delayed emptying syndromes, and proctalgia fugax may have “irritablebowel-syndrome-like” diseases and need to be studied with the same careful methodological consideration. The existence of diagnostic criteria for irritable bowel syndrome, however, does not imply the validity of the diagnosis, and if it is a valid diagnosis we should be able to distinguish it from other medical and psychiatric illnesses.
themselves
their
bowel late
BOWEL
SYNDROME
A VALID
DIAGNOSIS?
By definition, a syndrome is a collection of symptoms and signs that co-vary. How unique is the set of symptoms and signs of irritable bowel syndrome? How much overlap is there with other medical or psychiatric illness? Patients with irritable bowel syndrome manifest some symptoms that clearly suggest gastrointestinal distress (pain, distention, flatus, and urgency), but they also show features of autonomic arousal that are cornmon in mood and anxiety disorders, such as weakness, fatigue, palpitations, nervousness, dizziness, headache, hand tremor, back pain, sleep disturbance, and symptoms of sexual dysfunction (2, 23-26). It is the cornbination of these gastrointestinal and psychiatric symptoms that appears to separate patients with irritable bowel syndrome from other patients with pure gastrointestinal or psychiatric illness. Very little is known about the family histories of
566
28).
problems
syndrome
are
between
is rare
after
symptoms 10%-20%
like
individuals
bowel
onset
(32,
20 60
who
lower prevalence acteristics seen
and
age
with irritaattention to
age
40
its onset
15,
and
af-
The majority old, and the
(2).
years
(12).
Studies
have
found
irritable bowel syndrome population (15, 17, 30),
in in-
do
for
not
seek
syndrome
(15,
female
predominance
33),
may
a genetic
to have
before as males
those of of the general
irritable
jor
appears
females
condition
cluding
finding than
of patients paid more
sometimes
as many
of patients
this rather
(29).
bowel
twice
some
However,
the parents may have
adolescence,
fects
syndrome.
studies,
phenomenon
since syndrome
Irritable
in the elderly in patients with
medical
31).
The
care
early (34,
age
at
35),
(32) are similar panic disorder
and
to charand ma-
depression.
Irritable
bowel
condition with
occasional
with
the
rienced
by
with
of
recurrent
Are
there of the
drome varied
general
pain
and
been
found.
markers
patients
with
a higher
proportion
diet
and
However, bowel
also
who
have
clear,
activity
bowel
the
with
and
tions
of
perhaps
the
colon
marker
has many to
the
have
not
(43).
have
irritable
abnormality,
and have
but
some
both
they
the
do
not
in the basic electrical rhythm a physiological “trait” that
in the presence CNS.
that
this
related
Although regulates
Am
habits
remission
marker,
however,
that
to bowel
syndrome
motility
is directly
syndrome.
have van-
appear
do
this
bowel
confers vulnerability tors, perhaps from
It is not
syn-
subjects,
symptom
patients
irritable and
De-
bowel
motility, studies methodological
is unrelated
correlate. This variation of the gut may represent
tric
irritable
syndrome
despite
syndrome
symptoms
character-
control
bowel
persists
with
are
syndrome?
of “slow” (3 cycles/mm) myoelecdistal colon (38-42). This abnor-
many
patients
frequently
physiological
tric activity in the mality in electrical activity or
to be that
that
with
irritable
be
gastrointestialthough their
bowel
characteristic
chil-
may
syndrome.
irritable
Compared
in
(which
appear
agreement
no
expe-
and
37). This is consistent disorders and somatiza-
is a disorder of intestinal in their control of critical
ables,
(2),
bowel syndrome), to remain chronic,
with
adults
syndrome
as children
physiological
patients
a chronic symptoms
of the
bowel
severity varies over time (36, with the chronicity of anxiety tion disorder, both of which associated with irritable bowel istic
be
waning
One-third
abdominal
of irritable symptoms tend
to
and
irritable
symptoms
precursor
nal
appears
waxing
exacerbations.
diagnosis similar
dren
syndrome
marked
spite IS IRRITABLE
(27,
a learned
phenomenon, ble bowel
in
Although studies sugmay run in families. Twohalf of the siblings of children pain suffered abdominal
genetic
that
represent
distension.
no
of the
thirds pain
of
been
bowel
have
with
of mucus,
irritable
with
there
to it
of additional
abnormal
symptoms seems to
slower
are
J
Psychiatry
myoelecof
be
contrac-
and
I 47:5,
irritable
associated
frequency
nonpropulsive
fac-
segmen-
May
I 990
a
WALKER,
TABLE 1. Studies of Coexisting Gastrointestinal
Study Liss et al. (3) Young et al. (4) Fava and Pavan (5) Latimer et al. (6) Wender and Kalm
Ford
et al. (8)
aSome
patients
25 29 20 16 22
(7)a
48 had
more
than
one
diagnosis,
Psychiatric Measure
0 33 40 17 0 16
RDC RDC RDC RDC RDC RDC
#{149}
total
percent
reflects
may experience pain differently, both quantitatively and qualitatively. Patients with irritable bowel syndrome report gastrointestinal pain sooner and more intensely than control subjects when subjected to stepwise colonic balloon distention (44, 48, 49), although the methodology of these studies has been criticized (SO). Furthermore, two studies (49, 51) have found that patients with irritable bowel syndrome experience pain in unusual, atypical abdominal sites (upper abdomen) as well as in extra-abdominal sites. J ust as there have been no definitive biological markens for irritable bowel syndrome, there do not appear to be any characteristic psychological markers either. Although patients with irritable bowel syndrome ane more
distressed
than
normal
subjects,
they do not have a common psychological profile on standard psychological assessment instruments such as the MMPI. The recent establishment of diagnostic criteria for irritable bowel syndrome should improve the chances of more accurately identifying the characteristics of the syndrome. We accept the imprecision of previous definitions and will attempt to examine clinical features of irritable bowel syndrome as they were defined in each study. What is the evidence that irritable bowel syndrome
Am
J
Psychiatry
147:5,
May
1990
With
Anxiety
#{149}
Coexistin
g Psychiatric
a nd
Gastroint
estinal
the
Affective
Hysteria
Other
Total
N
%
N
%
N
%
N
%
N
%
6 1 1 3 3
24 4 S 19 14
2 5 9 5 11
8 17 45 31 50
7 5 3 2
28 17 15 13
-
8 32 10 35 1 S 6 32 7 32
-
-
-
-
23 21 14 16 16 26
92 72 70 100 73 54
time
in
-
tal and impede normal penistaltic fecal movement (39), these slower frequency contractions are not more frequent at rest in patients with irritable bowel syndrome than in normal subjects. However, in patients with irritable bowel syndrome they become more frequent following infusions of cholecystokinin and pentagastnin (39), food ingestion (40), or balloon distention of the colon (44) and seem to be associated with pain in patients with irritable bowel syndrome who have prominent meal-associated symptoms (45). Some investigatons (46, 47) have shown abnormalities in small bowel motility as well, suggesting involvement of 1evels of the gastrointestinal tract outside the colon. Thus, patients with irritable bowel syndrome may have a sensitive gastrointestinal tract that responds in an exaggerated way to stimuli which normally regulate moton activity. In addition, patients with irritable bowel syndrome
psychologically
KATON
Disorders
Number of Control Subjects
but
AND
and Psychiatric Symptoms in Patients With Irritable Bowel Syndrome Subjects
Number of Subjects
ROY-BYRNE,
percent
of the
entire
sample
and psychiatric symptoms the same individual?
PSYCHIATRIC IRRITABLE
-
with
any
-
-
diagnosis.
occur
at the
ILLNESS IN PATIENTS BOWEL SYNDROME
same
WITH
Studies of coexisting gastrointestinal and psychiatric symptoms in patients with irritable bowel syndrome have been difficult to compare due to methodological differences. However, more recent studies show a consistent trend toward substantial psychiatric illness in this population, as illustrated in table 1. Interpretation of these studies is problematic. First, Research Diagnostic Criteria prevent the simultaneous diagnosis of anxiety disorders when a primary affective illness diagnosis is made, and since estimates suggest that 25%-33% of patients with depression may also suffer from a concurrent anxiety disorder (52), the prevalence of anxiety diagnoses is most likely considerably higher than these studies suggest. Second, some patients receiving the diagnosis of “hysteria” (who would probably now meet criteria for somatization disorder) may well have had panic disorder, since the Epidemiologic Catchment Area data have demonstrated considerable overlap of symptom criteria between panic disorder and somatization disorder (53). Nonetheless, the total percentage of patients with psychopathology is very high in groups with irritable bowel syndrome. Although there is evidence for an association, what is the nature of this relationship? Hypothesis Precursor
1 : Irritable of Psychiatric
Bowel Illness
Syndrome
Is a
The essential feature of the somatopsychic hypothesis is that psychiatric symptoms develop as a consequence of on as a reaction to the chronic stress of coping with gastrointestinal disease. This is similar to the situation in which depression develops secondarily to a medical disease such as cancer. For this hypothesis to be valid, two conditions must be satisfied. 1) The timing of the symptoms of irritable bowel syndrome must precede the development of psychiatric symptoms. 2)
567
IRRITABLE
BOWEL
SYNDROME
There should disorders can
be evidence that other gastrointestinal create similar psychiatric sequelae. We could not find any studies to support the idea that symptoms of irritable bowel syndrome temporally precede mood or anxiety symptoms. However, there have been studies of other syndromes frequently considered in the differential diagnostic assessment of innitable bowel syndrome. Although ulcerative colitis has been considered one of the classical psychosomatic diseases, patients with this disorder are no more likely to have current or lifetime psychiatric diagnoses than medically ill control subjects (54). Conversely, patients with Crohn’s disease have been found to have a significantly higher prevalence of psychiatric illness than medically ill control subjects (55). However, Crohn’s disease is more likely than ulcerative colitis to lead to a course of treatment involving multiple surgeries and colostomy, chronic steroid use, and hyperalimentation. This may lead to a higher prevalence of secondary psychiatric illness in patients with this disorder. Although patients with Crohn’s disease have a higher prevalence of psychiatric illness than patients with ulcerative colitis, the prevalence is still far below that of patients with irritable bowel syndrome. It would appear from these studies that the magnitude of the psychiatric illness found in patients with irritable bowel syndrome cannot be explained simply as a reaction to the chronic stress of physical disease.
Hypothesis Fruste
2: Irritable
of Psychiatric
Bowel
Syndrome
Is a Forme
Illness
Could irritable bowel syndrome be a somatic expression of psychiatric illness? This psychosomatic or psychophysiological hypothesis asserts that the gastrointestinal manifestations of irritable bowel syndrome are either secondary somatic reactions to psychological distress or amplifications of mildly aversive symptoms that are normally present but are reified into a “disorder” by psychological factors. Essential featunes of this hypothesis are that 1) the timing of symptoms must be preceded by psychological distress and psychiatric illness, 2) these a priori psychological factons must affect the way symptoms are manifested on experienced in irritable bowel syndrome, and 3) effective treatments for the underlying psychiatric illness should have efficacy in removing the gastrointestinal symptoms as well. The timing of symptoms. Although there are many studies of the psychological characteristics of patients with irritable bowel syndrome (3, 4, 8, 56-59), only a few studies (3, 4, 8) have reliably measured the relative timing of psychiatric symptoms and irritable bowel syndrome symptoms. These studies suggested that the onset of psychiatric illness frequently precedes the onset of gastrointestinal symptoms in the majority of patients with functional gastrointestinal disorders. Preliminary data from our ongoing study of psychiatric epidemiology in patients with irritable bowel syndrome support these findings. When a consecutive
568
sample of 13 patients with irritable bowel syndrome was compared with a similar sample of 10 patients diagnosed with inflammatory bowel disease in a prospective design with structured psychiatric interviewing (the National Institute of Mental Health Diagnostic Interview Schedule), patients with irritable bowel syndrome were more likely than control subjects to have had a history of anxiety (85% versus 20%; p
Bowel
A. Walker,
Syndrome
M.D.,
Peter
P. Roy-Byrne,
Psychiatric illnesses such as mood, anxiety, and somatization disorders share many common features with irritable bowel syndrome. The authors review recent developments in the definition of irritable bowel syndrome and its relationship to psychiatric illness, discuss the diagnostic validity of irritable bowel syndrome from several perspectives, and offer a pathophysiological model of irritable bowel syndrome that integrates many of the biological and psychosocial fi ndings of earlier studies. Psychiatric evaluation appears to be an important factor in the diagnosis and treatment of patients with irritable bowel syndrome. (Am J Psychiatry 1990; 147:565-572)
I
rritable
bowel
trointestinal
syndrome disorder
its
definition
and
its
status
as
of
J.
M.D.,
and
syndrome 1) Irritable
and psychiatric illness could be rebowel syndrome could be a precursor disorders. This view holds that psychi-
psychiatric
atnic symptoms chronic physical
Wayne
develop disease
Katon,
secondary to the (a “somatopsychic”
Irritable bowel syndrome could or forme fruste of psychiatric
2)
non
chosomatic” idea
This
when
symptoms
view
stress of a model).
be an epiphenomedisorders (a “psy-
is compatible
with
the
those of irritable bowel synare common in the general population and, amplified by psychiatric illness, reach the status
drome of
model).
that
M.D.
disease
a
like
or disorder
(15).
common
gas-
by primary
care
psychiatric
physicians and gastroenterologists: prevalence figures range from 13% to 52% of new referrals to gastrointestinal clinics (1, 2). Despite the high prevalence of this disorder, however, there is incomplete agreement on
bowel lated.
Illness
further evaluate the relationship of irritable syndrome and psychiatric illness, we will exfour questions: 1) What is known about the definition and diagnostic validity of irritable bowel syndrome? 2) How are irritable bowel syndrome and
is the most encountered
and Psychiatric
a valid
To bowel plore
symptoms
iological
model
for
related? irritable
3) Is there bowel
a pathophys-
syndrome
that
in-
cludes a neurobiological component? and 4) What is the role of the psychiatrist in the evaluation and treatment of patients with irritable bowel syndrome?
diagnostic
entity.
One
of the more
striking
features
of this
syndrome
is
the frequent finding of associated psychiatric illness, especially mood, anxiety, and somatization disorders. Studies
have
suggested
that
54%-100%
of
patients
with irritable bowel syndrome may have associated psychiatric illness (3-8). Although the psychological characteristics
irritable
and
bowel
psychiatric
syndrome
viewed (9-13), the been well established. The clarification
Methodological dromes such demonstrated delimitation
atric
There
have
nature of
as the from
been
has
re-
two
possible
J
Psychiatry
147:5,
May
1990
syndrome
sion, cient
syn-
nosis
names,
SYNDROME?
each
avoid
the
trap
by exclusion,
nate
of heterogeneity
Manning
ther
diagnostic
with
irritable
with
organic
disease.
refined
models
by Thompson
bowel and
in diag-
the
to discrimi-
syndrome criteria
Heaton
suffi-
suggested
criteria These
of
bowel exclu-
lack
inherent
et al. (16)
patients
patients
changing
to patients whose symptoms for an organic etiology.
of operationalized
use
reflecting
psychological etiology (9). Irritable has been considered a diagnosis of
assigned evidence
To
(17),
from were
fur-
Drossman
al. (15), Whitehead and Schuster (18), and, most recently, by an international congress on gastroenterology in Rome (Drossman, 1988, personal communication). The congress defined irritable bowel syndrome as follows:
et
ways
that
irritable
Received April 25, 1989; revisions received July 12 and Sept. 6, 1989; accepted Sept. 18, 1989. From the Department of Psychiatry and Behavioral Sciences, Division of Consultation-Liaison, University of Washington. Address reprint requests to Dr. Walker, Department of Psychiatry and Behavioral Sciences, Division of Consultation-Liaison, University of Washington, Seattle, WA 98195. Copyright © 1990 American Psychiatric Association.
Am
and
organic
not
populations.
at least
BOWEL
It is not easy to define what irritable bowel syndrome is but easy to say what it is not. Since its initial description by Powell in 1820, it has been described by
is important.
heterogeneous
IS IRRITABLE
30 different
with
extensively
association
relationship
of other
of patients
premenstrual syndrome (14) have importance of careful definition and other disorders, particularly psychito avoid the problems inherent in
heterogeneous
are
of this
this
critiques
conditions,
studying
illnesses
WHAT
Continuous
or
1. Abdominal ated
with
recurrent
pain, change
symptoms
relieved in frequency
of:
with
defecation or
consistency
or associof
stool,
and/or
565
IRRITABLE
2.
BOWEL
SYNDROME
Disturbed
defecation
a)
altered
stool
frequency,
b)
altered
stool
form
c)
altered
stool
passage
ing
d)
incomplete
passage
usually
with
3.
Bloating
Noting patients
of
the with
(two
or
(hard
more
of):
patients
or loose/watery),
(straining
or
urgency,
feel-
evacuation),
or
feeling
high irritable
gested
abdominal
the symptoms parents and recurrent abdominal
prevalence bowel
of emotional syndrome,
distress Whitehead
in et
al. (18, 19) suggested that psychological criteria be incorporated into the definition. Additionally, proposed the need for two distinct sets of criteria,
also they one for research and another for clinical use. Research diagnostic criteria would select a specific, narrowly defined, homogeneous population for epidemiologic and treatment outcome studies, but a more sensitive, broad set of clinical criteria could be used for treatment in outpatient clinics. Although irritable bowel syndrome was first recognized as a disorder of the colon, some gastroenterologists feel that because the motility and functioning of various parts of the gastrointestinal tract are more alike than dissimilar, irritable bowel syndrome may represent a continuum of similar gastrointestinal diagnoses with symptoms that are site-specific depending on the level of involvement (20-22). Thus, patients with esophageal symptoms, delayed emptying syndromes, and proctalgia fugax may have “irritablebowel-syndrome-like” diseases and need to be studied with the same careful methodological consideration. The existence of diagnostic criteria for irritable bowel syndrome, however, does not imply the validity of the diagnosis, and if it is a valid diagnosis we should be able to distinguish it from other medical and psychiatric illnesses.
themselves
their
bowel late
BOWEL
SYNDROME
A VALID
DIAGNOSIS?
By definition, a syndrome is a collection of symptoms and signs that co-vary. How unique is the set of symptoms and signs of irritable bowel syndrome? How much overlap is there with other medical or psychiatric illness? Patients with irritable bowel syndrome manifest some symptoms that clearly suggest gastrointestinal distress (pain, distention, flatus, and urgency), but they also show features of autonomic arousal that are cornmon in mood and anxiety disorders, such as weakness, fatigue, palpitations, nervousness, dizziness, headache, hand tremor, back pain, sleep disturbance, and symptoms of sexual dysfunction (2, 23-26). It is the cornbination of these gastrointestinal and psychiatric symptoms that appears to separate patients with irritable bowel syndrome from other patients with pure gastrointestinal or psychiatric illness. Very little is known about the family histories of
566
28).
problems
syndrome
are
between
is rare
after
symptoms 10%-20%
like
individuals
bowel
onset
(32,
20 60
who
lower prevalence acteristics seen
and
age
with irritaattention to
age
40
its onset
15,
and
af-
The majority old, and the
(2).
years
(12).
Studies
have
found
irritable bowel syndrome population (15, 17, 30),
in in-
do
for
not
seek
syndrome
(15,
female
predominance
33),
may
a genetic
to have
before as males
those of of the general
irritable
jor
appears
females
condition
cluding
finding than
of patients paid more
sometimes
as many
of patients
this rather
(29).
bowel
twice
some
However,
the parents may have
adolescence,
fects
syndrome.
studies,
phenomenon
since syndrome
Irritable
in the elderly in patients with
medical
31).
The
care
early (34,
age
at
35),
(32) are similar panic disorder
and
to charand ma-
depression.
Irritable
bowel
condition with
occasional
with
the
rienced
by
with
of
recurrent
Are
there of the
drome varied
general
pain
and
been
found.
markers
patients
with
a higher
proportion
diet
and
However, bowel
also
who
have
clear,
activity
bowel
the
with
and
tions
of
perhaps
the
colon
marker
has many to
the
have
not
(43).
have
irritable
abnormality,
and have
but
some
both
they
the
do
not
in the basic electrical rhythm a physiological “trait” that
in the presence CNS.
that
this
related
Although regulates
Am
habits
remission
marker,
however,
that
to bowel
syndrome
motility
is directly
syndrome.
have van-
appear
do
this
bowel
confers vulnerability tors, perhaps from
It is not
syn-
subjects,
symptom
patients
irritable and
De-
bowel
motility, studies methodological
is unrelated
correlate. This variation of the gut may represent
tric
irritable
syndrome
despite
syndrome
symptoms
character-
control
bowel
persists
with
are
syndrome?
of “slow” (3 cycles/mm) myoelecdistal colon (38-42). This abnor-
many
patients
frequently
physiological
tric activity in the mality in electrical activity or
to be that
that
with
irritable
be
gastrointestialthough their
bowel
characteristic
chil-
may
syndrome.
irritable
Compared
in
(which
appear
agreement
no
expe-
and
37). This is consistent disorders and somatiza-
is a disorder of intestinal in their control of critical
ables,
(2),
bowel syndrome), to remain chronic,
with
adults
syndrome
as children
physiological
patients
a chronic symptoms
of the
bowel
severity varies over time (36, with the chronicity of anxiety tion disorder, both of which associated with irritable bowel istic
be
waning
One-third
abdominal
of irritable symptoms tend
to
and
irritable
symptoms
precursor
nal
appears
waxing
exacerbations.
diagnosis similar
dren
syndrome
marked
spite IS IRRITABLE
(27,
a learned
phenomenon, ble bowel
in
Although studies sugmay run in families. Twohalf of the siblings of children pain suffered abdominal
genetic
that
represent
distension.
no
of the
thirds pain
of
been
bowel
have
with
of mucus,
irritable
with
there
to it
of additional
abnormal
symptoms seems to
slower
are
J
Psychiatry
myoelecof
be
contrac-
and
I 47:5,
irritable
associated
frequency
nonpropulsive
fac-
segmen-
May
I 990
a
WALKER,
TABLE 1. Studies of Coexisting Gastrointestinal
Study Liss et al. (3) Young et al. (4) Fava and Pavan (5) Latimer et al. (6) Wender and Kalm
Ford
et al. (8)
aSome
patients
25 29 20 16 22
(7)a
48 had
more
than
one
diagnosis,
Psychiatric Measure
0 33 40 17 0 16
RDC RDC RDC RDC RDC RDC
#{149}
total
percent
reflects
may experience pain differently, both quantitatively and qualitatively. Patients with irritable bowel syndrome report gastrointestinal pain sooner and more intensely than control subjects when subjected to stepwise colonic balloon distention (44, 48, 49), although the methodology of these studies has been criticized (SO). Furthermore, two studies (49, 51) have found that patients with irritable bowel syndrome experience pain in unusual, atypical abdominal sites (upper abdomen) as well as in extra-abdominal sites. J ust as there have been no definitive biological markens for irritable bowel syndrome, there do not appear to be any characteristic psychological markers either. Although patients with irritable bowel syndrome ane more
distressed
than
normal
subjects,
they do not have a common psychological profile on standard psychological assessment instruments such as the MMPI. The recent establishment of diagnostic criteria for irritable bowel syndrome should improve the chances of more accurately identifying the characteristics of the syndrome. We accept the imprecision of previous definitions and will attempt to examine clinical features of irritable bowel syndrome as they were defined in each study. What is the evidence that irritable bowel syndrome
Am
J
Psychiatry
147:5,
May
1990
With
Anxiety
#{149}
Coexistin
g Psychiatric
a nd
Gastroint
estinal
the
Affective
Hysteria
Other
Total
N
%
N
%
N
%
N
%
N
%
6 1 1 3 3
24 4 S 19 14
2 5 9 5 11
8 17 45 31 50
7 5 3 2
28 17 15 13
-
8 32 10 35 1 S 6 32 7 32
-
-
-
-
23 21 14 16 16 26
92 72 70 100 73 54
time
in
-
tal and impede normal penistaltic fecal movement (39), these slower frequency contractions are not more frequent at rest in patients with irritable bowel syndrome than in normal subjects. However, in patients with irritable bowel syndrome they become more frequent following infusions of cholecystokinin and pentagastnin (39), food ingestion (40), or balloon distention of the colon (44) and seem to be associated with pain in patients with irritable bowel syndrome who have prominent meal-associated symptoms (45). Some investigatons (46, 47) have shown abnormalities in small bowel motility as well, suggesting involvement of 1evels of the gastrointestinal tract outside the colon. Thus, patients with irritable bowel syndrome may have a sensitive gastrointestinal tract that responds in an exaggerated way to stimuli which normally regulate moton activity. In addition, patients with irritable bowel syndrome
psychologically
KATON
Disorders
Number of Control Subjects
but
AND
and Psychiatric Symptoms in Patients With Irritable Bowel Syndrome Subjects
Number of Subjects
ROY-BYRNE,
percent
of the
entire
sample
and psychiatric symptoms the same individual?
PSYCHIATRIC IRRITABLE
-
with
any
-
-
diagnosis.
occur
at the
ILLNESS IN PATIENTS BOWEL SYNDROME
same
WITH
Studies of coexisting gastrointestinal and psychiatric symptoms in patients with irritable bowel syndrome have been difficult to compare due to methodological differences. However, more recent studies show a consistent trend toward substantial psychiatric illness in this population, as illustrated in table 1. Interpretation of these studies is problematic. First, Research Diagnostic Criteria prevent the simultaneous diagnosis of anxiety disorders when a primary affective illness diagnosis is made, and since estimates suggest that 25%-33% of patients with depression may also suffer from a concurrent anxiety disorder (52), the prevalence of anxiety diagnoses is most likely considerably higher than these studies suggest. Second, some patients receiving the diagnosis of “hysteria” (who would probably now meet criteria for somatization disorder) may well have had panic disorder, since the Epidemiologic Catchment Area data have demonstrated considerable overlap of symptom criteria between panic disorder and somatization disorder (53). Nonetheless, the total percentage of patients with psychopathology is very high in groups with irritable bowel syndrome. Although there is evidence for an association, what is the nature of this relationship? Hypothesis Precursor
1 : Irritable of Psychiatric
Bowel Illness
Syndrome
Is a
The essential feature of the somatopsychic hypothesis is that psychiatric symptoms develop as a consequence of on as a reaction to the chronic stress of coping with gastrointestinal disease. This is similar to the situation in which depression develops secondarily to a medical disease such as cancer. For this hypothesis to be valid, two conditions must be satisfied. 1) The timing of the symptoms of irritable bowel syndrome must precede the development of psychiatric symptoms. 2)
567
IRRITABLE
BOWEL
SYNDROME
There should disorders can
be evidence that other gastrointestinal create similar psychiatric sequelae. We could not find any studies to support the idea that symptoms of irritable bowel syndrome temporally precede mood or anxiety symptoms. However, there have been studies of other syndromes frequently considered in the differential diagnostic assessment of innitable bowel syndrome. Although ulcerative colitis has been considered one of the classical psychosomatic diseases, patients with this disorder are no more likely to have current or lifetime psychiatric diagnoses than medically ill control subjects (54). Conversely, patients with Crohn’s disease have been found to have a significantly higher prevalence of psychiatric illness than medically ill control subjects (55). However, Crohn’s disease is more likely than ulcerative colitis to lead to a course of treatment involving multiple surgeries and colostomy, chronic steroid use, and hyperalimentation. This may lead to a higher prevalence of secondary psychiatric illness in patients with this disorder. Although patients with Crohn’s disease have a higher prevalence of psychiatric illness than patients with ulcerative colitis, the prevalence is still far below that of patients with irritable bowel syndrome. It would appear from these studies that the magnitude of the psychiatric illness found in patients with irritable bowel syndrome cannot be explained simply as a reaction to the chronic stress of physical disease.
Hypothesis Fruste
2: Irritable
of Psychiatric
Bowel
Syndrome
Is a Forme
Illness
Could irritable bowel syndrome be a somatic expression of psychiatric illness? This psychosomatic or psychophysiological hypothesis asserts that the gastrointestinal manifestations of irritable bowel syndrome are either secondary somatic reactions to psychological distress or amplifications of mildly aversive symptoms that are normally present but are reified into a “disorder” by psychological factors. Essential featunes of this hypothesis are that 1) the timing of symptoms must be preceded by psychological distress and psychiatric illness, 2) these a priori psychological factons must affect the way symptoms are manifested on experienced in irritable bowel syndrome, and 3) effective treatments for the underlying psychiatric illness should have efficacy in removing the gastrointestinal symptoms as well. The timing of symptoms. Although there are many studies of the psychological characteristics of patients with irritable bowel syndrome (3, 4, 8, 56-59), only a few studies (3, 4, 8) have reliably measured the relative timing of psychiatric symptoms and irritable bowel syndrome symptoms. These studies suggested that the onset of psychiatric illness frequently precedes the onset of gastrointestinal symptoms in the majority of patients with functional gastrointestinal disorders. Preliminary data from our ongoing study of psychiatric epidemiology in patients with irritable bowel syndrome support these findings. When a consecutive
568
sample of 13 patients with irritable bowel syndrome was compared with a similar sample of 10 patients diagnosed with inflammatory bowel disease in a prospective design with structured psychiatric interviewing (the National Institute of Mental Health Diagnostic Interview Schedule), patients with irritable bowel syndrome were more likely than control subjects to have had a history of anxiety (85% versus 20%; p
