Risa B. Weisberg
Overview of Generalized Anxiety Disorder:
Epidemiology, Presentation, and Course
Risa B. Weisberg, PhD
Generalized anxiety disorder (GAD) was defined relatively recently, and the diagnostic criteria are
still being refined. The essential feature of the disorder has changed from persistent anxiety to excessive worry, and the required symptom duration has changed from 1 month to 6 months. Additionally,
exclusion criteria involving permissibility of the diagnosis in children and wording regarding the relationship of GAD with mood disorders have changed. Nosologic controversies still surround the criteria for excessive worry, symptom duration, the relationship between GAD and major depressive disorder, and the required number of associated symptoms. Alterations in the criteria have been suggested,
but more research is needed on the validity of these proposed changes. Generalized anxiety disorder
appears to be highly prevalent. In the United States, the lifetime prevalence of DSM-IV GAD is estimated to be about 5% and the current prevalence to be about 2% to 3%. The disorder is differentially
prevalent across gender and ethnic and social groups. The course of GAD is chronic and can be exacerbated by poor family relationships, comorbid cluster C personality disorders, and comorbid Axis I
disorders. Impairment and suicidal ideation are associated with GAD.
(J Clin Psychiatry 2009;70[suppl 2]:4–9)
G
eneralized anxiety disorder (GAD) was defined relatively recently, in 1980. The Diagnostic and Statistical Manual of Mental Disorders (DSM) definition of the
disorder underwent modification from DSM-III to DSMIII-R and to DSM-IV and DSM-IV-TR (Table 1).1–4 The
validity of the definition of GAD is still questioned, and
several changes to the criteria for the disorder have been
suggested. Although diagnostic criteria have varied among
studies, available research has suggested that GAD is
highly prevalent, with a chronic course, significant impairment, and risk of suicidality.
EPIDEMIOLOGY OF GAD
Prevalence of DSM-IV GAD in the General Population
Recent prevalence studies have used DSM-IV criteria
to measure the rates of GAD. In the United States, ac-
From the Department of Psychiatry and Human Behavior and
the Department of Family Medicine, Brown University, Providence,
Rhode Island.
This article is derived from the planning teleconference series
“Insights Into Generalized Anxiety Disorder,” which was held
June–August 2008, and supported by an educational grant from
AstraZeneca Pharmaceuticals LP.
Dr Weisberg has received grant/research support from Pfizer
and from a Mentored Patient-Oriented Research Career Development
Award from the National Institute of Mental Health, K23 MH069595.
Corresponding author and reprints: Risa B. Weisberg, PhD,
Brown University, Box G-BH, Duncan Building, Providence, RI
02912 (e-mail: Risa_Weisberg@Brown.edu).
© Copyright 2009 Physicians Postgraduate Press, Inc.
4
cording to the National Comorbidity Survey Replication
(NCS-R),5 GAD was found to have a 5.7% lifetime prevalence,6 and the 12-month prevalence rate was reported to
be 3.1%.5 Other US epidemiologic studies have supported
these data and reported only slightly varying rates.7 Overall, the lifetime rate of GAD in American adults is thought
to be about 5%, and current prevalence rates are thought to
range from about 2% to 3%.8
In Europe, epidemiologic studies have reported more
variable rates of DSM-IV GAD, with lifetime prevalence
rates ranging from 0.1% to 6.9%, according to a metaanalysis9 of studies that used DSM-IV criteria in 6 European countries. The largest of these studies, an epidemiologic sample of over 21,000 adults in Western
Europe, reported a lifetime prevalence of DSM-IV GAD
of 2.8%.10
Prevalence Across Lifespan and Social Groups
The median age at onset of GAD in the US population
is estimated to be 31 years. Approximately 25% of cases
of GAD have an age at onset of 20 years and an additional
50% have an age at onset between 20 and 47 years.6 Similarly, European studies have found that GAD prevalence
increases from young adulthood through the mid-50s, a
pattern unlike that of other anxiety disorders.9 Therefore,
GAD is typically a disorder of adult onset. In fact, GAD
has the oldest median age at onset of any of the anxiety
disorders and has a pattern of age at onset that is more
similar to that of major depressive disorder (MDD) than it
is to the other anxiety disorders.6 In older adults (65 years
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J Clin Psychiatry 2009;70 (suppl 2)
GAD: Epidemiology, Presentation, and Course
FOR CLINICAL USE
◆ The prevalence of GAD appears to be higher among women; adults; whites; people with a
low income; and those who are widowed, separated, or divorced.
◆ Reduced likelihood of recovery and remission is associated with poor family relationships,
comorbid cluster C personality disorders, comorbid Axis I disorders, and female sex.
◆ Diagnostic criteria for GAD have been controversial since their introduction in 1980 and
still cause confusion and debate.
and older), the prevalence of anxiety disorders except
GAD appears to decrease compared with younger ages,
but the rate of GAD may actually grow; the current prevalence of GAD in older adults has been estimated to be
4%.11 However, a study12 of DSM-IV disorders in older
African-American adults (55 years and older) reported the
lifetime prevalence of GAD to be 3.09%, somewhat lower
than in the general population. In this sample,12 GAD was
found to be less prevalent than social phobia and posttraumatic stress disorder (PTSD) and also less prevalent than
MDD and alcohol abuse.
Scant data are available for the prevalence of DSM-IV
GAD in children and adolescents, in part due to changes
in nomenclature. Prior to DSM-III-R, the diagnosis of
GAD did not apply to children and adolescents. Even with
the DSM-III-R criteria allowing the GAD diagnosis in
younger patients, the symptoms of GAD in children overlapped with those of overanxious disorder. However,
available research suggests that strictly defined DSM-IV
GAD is uncommon in children and adolescents. Low lifetime rates of DSM-IV GAD in children were found in European studies (0.4 to 2.7%).9 Further, the 1-year prevalence of DSM-IV GAD was 0.5% in children and
adolescents in a US primary care site; this prevalence rate
was the lowest of any of the psychiatric disorders measured in the sample.13
Generalized anxiety disorder appears to be differentially prevalent across genders and cultural groups. The
disorder occurs approximately twice as often in women
as it does in men.4,14 Studies15,16 in the United States have
found that, besides female gender and older age, risk factors for GAD include having a low income and being widowed, separated, or divorced; groups that have a lower
risk for GAD are Asian, Latino, and black adults. A greater
12-month prevalence of GAD has been reported in lesbian
and bisexual women compared with heterosexual women
(14.7% vs 3.8%), but no difference has been found between gay men and heterosexual men.17
COURSE OF GAD
Generalized anxiety disorder is a long-term illness with
a high likelihood of recurrence. The course of GAD can be
predicted or exacerbated by several factors.
J Clin Psychiatry 2009;70 (suppl 2)
Probability of Recovery and Recurrence
The Epidemiologic Catchment Area (ECA) study,18
which used DSM-III criteria, reported that GAD persisted
for longer than 5 years in 40% of individuals who were
diagnosed with the disorder. Most of the available data on
the longitudinal course of GAD come from the HarvardBrown Anxiety Research Project (HARP) study,19 which
used DSM-III-R criteria. The HARP data support the
chronic nature of GAD, as reported in the ECA study,18
even though the GAD criteria changed considerably from
DSM-III to DSM-III-R (see Table 1). In HARP,19 over
12 years, DSM-III-R GAD was found to have a probability of recovery of 0.58, and the probability of recurrence in
patients who recovered was 0.45. During the 12 years of
the study, the average amount of time that patients with
GAD spent ill was 74%.
Utilizing data from the Primary Care Anxiety Project,
Rodriguez and colleagues20 examined the probability of
recovery in primary care patients with DSM-IV GAD. In
this sample, the probability of recovery was 0.39 over 2
years, which is somewhat higher than that at 2 years in the
HARP study.19 The difference in probability rates between
the 2 studies may relate to different population samples or
to differences between DSM-IV and DSM-III-R criteria,
but most of the methodology for these studies was very
similar. Rodriguez and colleagues20 found that older age at
onset and less severe psychosocial impairment were associated with an increased likelihood of recovery.
Predictors of the Course of GAD
Predictors of the course of GAD include the status
of family relationships, the presence of comorbidity, and
gender. Poor relationships with a spouse or relatives and
the presence of comorbid cluster C personality disorders
have been associated with a reduced likelihood of GAD
remission.21 Comorbid Axis I disorders have also been
found to affect the course of GAD; patients with GAD
who had comorbid MDD, panic disorder with agoraphobia, or substance use disorders were found to be less likely
to recover from GAD than those without these comorbid
disorders.19 Gender also seemed to affect the course of
GAD; women were found to be less likely to remit than
men, but they also appeared to be less likely to relapse
once they had remitted.22
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5
Risa B. Weisberg
Table 1. Evolution of Key Criteria for Generalized Anxiety Disorder in the Diagnostic and Statistical Manual of Mental Disorders
DSM-III, 1980a
Generalized, persistent anxiety of at least 1 month’s
duration, without symptoms of phobias, panic, or
obsessive compulsive disorder; or symptoms due
to another mental disorder, such as depressive
disorder or schizophrenia
Symptoms from 3 of the following
4 categories:
• Motor tension
• Autonomic hyperactivity
• Apprehensive expectation (including anxiety,
worry, fear) and vigilance
• Must be at least 18 years old (manifested as
“overanxious disorder” in children)
DSM-III-R, 1987b
Unrealistic or excessive worry
about 2 or more circumstances,
more days than not, for 6
months’ duration
At least 6 symptoms from the
following 3 categories:
• Motor tension
• Autonomic hyperactivity
• Vigilance/scanning
Symptoms must not occur
exclusively during the
course of a mood disorder
Diagnosis permissible and
identical in children. However,
diagnosis of overanxious
disorder continued to exist
with great overlap in criteria
for children
DSM-IV, 1994,c and
DSM-IV-TR, 2000d
Anxiety and worry that:
Are excessive and difficult to control, occur more
days than not for at least 6 months, and are about
a number of events or activities
Are associated with 3 or more of the
following 6 symptoms:
• Restlessness or feeling keyed up or on edge
• Being easily fatigued
• Difficulty concentrating or mind going blank
• Irritability
• Muscle tension
• Sleep disturbance
Cause significant distress or impairment
Do not occur exclusively during a mood
disorder, psychotic disorder, pervasive
developmental disorder, or posttraumatic
stress disorder
May occur in children
a
Based on American Psychiatric Association.1
Based on American Psychiatric Association.2
c
Based on American Psychiatric Association.3
d
Based on American Psychiatric Association.4
b
Impairment and Severity
Impairment and severity of GAD have been examined
in several studies. In the NCS-R,5 77% of GAD cases
were classified as being of moderate or serious severity,
which included having impairment in occupational or role
function. Similarly, in an Australian survey23 of current
DSM-IV disorders in the general population, 72% of respondents with GAD had moderate or severe disability according to the Medical Outcomes Study 12-Item Short
Form; no other anxiety disorder had a rate of moderate or
severe disability as high as that of GAD.
Significant impairment in life satisfaction and wellbeing is also associated with GAD. In a Canadian community sample,24 after controlling for the effects of MDD,
lifetime and current DSM-III-R GAD were both associated with decreased perceived overall well-being. Lifetime GAD was also associated with dissatisfaction with
the individual’s main activity in life and with family relationships. However, GAD was not independently associated with dissatisfaction with friendships, leisure activities, or income. In other large community surveys (using
both DSM-III-R and DSM-IV criteria),25–27 GAD was associated with impairment that was not only independent of
the effects of MDD but also equivalent in magnitude to the
impairment caused by MDD.
An association with suicide, in any disorder, is one of
the measures of impairment that has the greatest impact,
and epidemiologic data show that GAD may be uniquely
associated with suicidality. In a prospective population-
6
based survey28 of adults in the Netherlands, DSM-III-R
GAD was found to be an independent risk factor for
suicidal ideation, but not suicide attempts, after adjusting
for demographic factors and comorbid Axis I disorders.
In a large longitudinal study of young adults (16 to 25
years) in the United States,29 GAD was associated with a
6-fold increased likelihood of suicidal ideation and a more
than 2-fold greater likelihood of attempted suicide, after
controlling for other Axis I disorders and stressful life
events.
NOSOLOGY
Nosologic issues and controversies have existed since
GAD first appeared in the nomenclature in DSM-III. The
diagnostic criteria have been adjusted over time and continue to be debated.
Past Definitions of GAD
When GAD first appeared in DSM-III, the essential
features were generalized persistent anxiety that lasted
1 month or longer and did not contain symptoms of
phobia, panic, or obsessive compulsive disorder (see
Table 1). These features were substantially changed in the
DSM-III-R to worry that was unrealistic or excessive, that
was present for more days than not for at least 6 months,
and that was about 2 or more circumstances.
The original diagnosis of GAD required symptoms
from 3 of 4 categories. Diagnosis in the DSM-III-R
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GAD: Epidemiology, Presentation, and Course
revision, however, required 6 symptoms from 3 categories. Additionally, GAD could not occur exclusively during the course of a mood disorder.
In DSM-III criteria, the individual had to be at least 18
years of age to have GAD. If the individual had similar
symptoms and was a child or adolescent, the syndrome
was diagnosed as overanxious disorder. In DSM-III-R, a
diagnosis of GAD became permissible in children, but the
diagnosis of overanxious disorder still existed, leading to
a great deal of overlap in the criteria for children.
Poor interrater diagnostic reliability was found for
both DSM-III and DSM-III-R.30–32 High rates of comorbidity associated with GAD caused difficulty with diagnosis and in part sparked the change in the duration criterion from 1 month to 6 months in DSM-III-R; because of
the comorbidity, debate surrounded whether GAD was
a residual category or a prodrome of other anxiety disorders or MDD.31,32 Additionally, the 1-month duration had
caused challenges in distinguishing GAD from adjustment disorders or situational stress reactions.32
Remaining Nosologic Controversies
Controversies still surround the DSM-IV GAD criteria
(Table 1). Current debate relates to the duration and excessive worry criteria, the number of associated symptoms that should exist in order for GAD to be diagnosed,
and the relationship between GAD and MDD.
Duration. Changing the duration criterion would
affect estimates of the prevalence of GAD, but other
findings about GAD, such as family history and level of
work impairment, may not change. As might be expected,
the prevalence of GAD increases as the duration requirement decreases. An analysis33 of data from the NCS-R
found that if the DSM-IV minimum duration criterion was
changed from 6 months to between 1 and 12 months, the
lifetime prevalence of GAD changed from 6.1% to between 4.2% (12-month minimum duration requirement)
and 12.7% (1-month minimum duration requirement).
The 1-year prevalence changed from 2.9% to between
2.2% and 5.5% (12-month and 1-month minimum duration requirements, respectively). Angst and colleagues34
found that nearly half of the patients in a large Swiss prospective study who were treated for generalized anxiety
would not have met the 6-month duration requirement in
DSM-IV, and so they argued that this duration requirement may exclude some individuals who are significantly
impaired and seek treatment.
A duration requirement less than 6 months is generally
not associated with less comorbidity than the 6-month
criterion. The Swiss prospective study34 found that GAD
with a duration criterion of less than 6 months was associated with similar comorbidity of major depressive episodes, bipolar disorder, and suicide attempts compared
with GAD of 6 months’ duration. An examination33 of
NCS-R data also found that comorbidity rates were
J Clin Psychiatry 2009;70 (suppl 2)
similar between GAD defined by a 6-month minimum
duration and GAD defined by a 1-month minimum duration; among the 16 comorbid disorders measured, only
PTSD, panic disorder, major depression, and bipolar I disorder were significantly (P < .05) more common after
6 months. The odds of having comorbid dysthymia increased after 12 months. Episode duration appeared to increase social impairment but was unrelated to family or
parental history of GAD, age at onset, work impairment,
and persistence.33,34
Excessive worry. The DSM-IV criterion that states that
anxiety and worry must be excessive is controversial. One
of the changes in the criteria from DSM-III-R to DSM-IV
was that the worry no longer needed to be “unrealistic,”
but the requirement that worry was “excessive” was maintained (see Table 1). Excessive worry is not required by
the International Statistical Classification of Diseases,
10th Revision,35 for a diagnosis of GAD.
Ruscio and colleagues36 argued that the excessive
worry criterion poses diagnostic problems because of confusion over operationally defining the term, which leads
to inconsistency. The excessive worry criterion was associated with the lowest interrater agreement among GAD
diagnoses, and eliminating this criterion was associated
with a large increase in interrater reliability.37 An examination36 of NCS-R data compared participants who
met the full DSM-IV criteria for GAD with those who
met the criteria except for excessive worry; this study
showed that, when the excessive worry criterion was
dropped, the lifetime prevalence of the disorder increased
by about 40%.
Differences were found in the presentation of GAD
with and without excessive worry.36 Generalized anxiety
disorder with excessive worry was associated with an earlier age at onset, a more persistent course, greater odds
of having comorbid Axis I disorders, and greater symptom
severity. However, no differences were found in parental
history of GAD, functional impairment, and treatment
seeking among individuals with or without the excessive
worry criterion. Ruscio and colleagues36 argued that the
excessiveness criterion may leave out many individuals
who are impaired by subthreshold GAD.
Number of associated symptoms. In the DSM-IV, criteria for a GAD diagnosis require that 3 of 6 associated
symptoms be present (Table 1); however, whether or not
3 symptoms is the optimal threshold is unclear. Little
research has examined this issue, but Brown and colleagues38 reported that 4 rather than 3 symptoms appear to
be optimal with regard to sensitivity and specificity.
Ruscio and colleagues39 suggested relaxing the criterion for associated symptoms from 3 to 2. Requiring only
2 of the 3 associated symptoms had little effect on GAD
prevalence in NCS-R data because fewer than 8% of
participants who endorsed any of the symptoms endorsed
only 2 of them. In fact, Breslau and Davis40 reported that
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Risa B. Weisberg
74% of patients with a 1-month or longer duration of GAD
reported 6 symptoms.
Independence from mood disorders. Current DSM-IV
criteria state that GAD may not occur exclusively during
the course of a mood disorder. However, data suggest
that this exclusion may not be valid. Zimmerman and
Chelminski41 compared 3 groups of patients with MDD;
1 group had only MDD, 1 group had MDD and comorbid
DSM-IV GAD, and 1 group had MDD and comorbid
GAD that met all criteria except the mood disorder exclusion. The investigators found that the 2 groups of patients with comorbid GAD did not differ; compared with
patients with only MDD, those in both GAD groups had
poorer social functioning, more suicidal ideation, more
anxiety and other disorders, a greater frequency of GAD
in family members, and a higher level of pathological
worry.
Simultaneous relaxation of criteria. Ruscio and colleagues39 examined the implications of simultaneously
broadening the GAD criteria by reducing the 6-month duration to 1 month, including worry that patients do not describe as excessive, and decreasing associated symptoms
from 3 to 2. Broadening just the duration and excessiveness criteria more than doubled the GAD lifetime prevalence (12.8%), and relaxing all 3 criteria resulted in a
13.7% lifetime prevalence. As the criteria were increasingly broadened, cases were associated with less Axis I
comorbidity and with lower odds for the subsequent onset
of other disorders, although most of these differences
were not statistically significant. Because the temporal order of the disorders was determined from retrospective
data, further prospective longitudinal studies are needed.
The methods used by Ruscio and colleagues39 did not allow for examination of the relaxation of the MDD hierarchy because the investigators dropped all hierarchical exclusions in their analyses.
CONCLUSION
Generalized anxiety disorder is a relatively newly
defined disorder that, as described by DSM-III-R and
DSM-IV, appears to be highly prevalent, particularly
among women, non-Latino whites, and older adults. The
disorder has a fairly chronic course and is associated with
significant impairment in functioning, independent of the
effects of comorbid disorders, including MDD. Further,
GAD is independently associated with increased risk of
suicidality. The GAD diagnostic criteria have changed
throughout iterations of the DSM, and their validity still
remains in question. More research is needed to determine
whether proposed further alterations of GAD criteria
would dramatically change the course and presentation of
the disorder.
Disclosure of off-label usage: The author has determined that,
to the best of her knowledge, no investigational information
8
about pharmaceutical agents that is outside US Food and Drug
Administration–approved labeling has been presented in this article.
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