Obsessive-Compulsive Disorder and Generalized Anxiety Disorder: A Common Diagnostic Dilemma

Marco A. Grados, MD, MPH, Denise Leung, MD,
Khalid Ahmed, MD, and Alka Aneja, MD

Dr. Grados is assistant professor of psychiatry, Dr. Leung is resident in psychiatry, Dr. Ahmed is a fellow in child psychiatry, and Dr. Aneja is a fellow in child psychiatry at the Johns Hopkins School of Medicine in Baltimore, Maryland.

Disclosure: Dr. Grados received grant and/or research support from the National Institutes of Health. Drs. Leung, Ahmed, and Aneja do not have any affiliations or financial interests in a commercial organization that might pose a conflict of interest.

Please direct all correspondence to: Marco A. Grados, MD, MPH, 550 North Broadway #206, Baltimore, MD 21205; Tel: 443-287-2292; Fax: 443-287-4346; E-mail: [email protected].

Abstract

Generalized anxiety disorder is characterized by uncontrollable excessive worrying about everyday matters, including perception by others, achievement, danger, and safety. Obsessive-compulsive disorder is characterized by intrusive, senseless, and distressing ideations, images, or urges (ie, obsessions) and/or rigidly defined behaviors that must be applied to allay anxiety (ie, compulsions). Both conditions are characterized by excessive worrying. This article reviews the epidemiology, clinical presentation, and clinical course of both disorders, providing guidelines for the differential diagnosis.

Introduction

The overlap between generalized anxiety disorder (GAD) and obsessive-compulsive disorder (OCD) is based on phenomenological as well as possible pathophysiological commonalities. GAD includes excessive anxiety over daily life situations, while OCD is characterized by more specific anxiety with regard to overvalued ideas of disgust, contamination, responsibility, harm, symmetry, and hoarding. Common clinical features may include repetitive cognitive intrusions, negative emotions, difficulty dismissing the intrusion, and loss of mental control.¹

However, GAD and OCD are also categorically distinct in their clinical presentation and underlying risk factors: GAD usually presents as somatic concerns reflecting physiological anxiety that are openly admitted, while patients with OCD are secretive and do not readily disclose their symptoms. GAD is highly concurrent with mood symptoms, while OCD is more frequently seen in individuals with childhood vulnerabilities, such as tics and separation anxiety.

Both disorders present challenges for diagnosis in a primary care setting: patients with GAD may be treated for somatic complaints and patients with OCD may not disclose their symptoms despite their impairing nature. This article presents the main characteristics of both GAD and OCD and then emphasizes key differences to highlight the methods of differential diagnosis between both disorders.

Generalized Anxiety Disorder

Epidemiology

Various epidemiological reports estimate the prevalence of GAD to be between 3% and 8% of the population. The National Comorbidity Survey (NCS)² has estimated that GAD has a 12-month prevalence of 3.1%, a lifetime prevalence of 7% to 8%, and a point prevalence of 1.5%, using Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III),³ diagnostic criteria. Lifetime prevalence according to the Epidemiologic Catchment Area Study (ECA) study⁴ ranged by site from 4.1% to 6.6%. The Psychological Problems in General Health Care study⁵ estimated that 7.9% of primary care patients met International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10),⁶ criteria for a diagnosis of GAD.

Epidemiologic data have also shown that GAD occurs with double the frequency in women than in men.⁵ Other correlates of increased incidence of GAD include unmarried status, racial minority, and low socioeconomic status.⁷

Disability associated with GAD has been found to be as great as for major depressive disorder (MDD) with even greater impairment if these conditions are found comorbidly. The United States Mid-Life Survey⁷ showed that the average per capita number of work impairment days associated with GAD was 6 days per year, the highest number of work impairment days among physical and psychiatric conditions.⁸ In 1990, the cost of all anxiety disorders was estimated to be approximately $42.3 billion, with 54% of the total cost being spent on nonpsychiatric medical care and 31% being spent on psychiatric treatment.⁸ Indirect costs (eg, missed work time, mortality) accounted for approximately 13% of the total economic burden.⁸ Up to one third of patients presenting to primary care clinics with somatic complaints have a mood or anxiety disorder; it is not surprising then that GAD has been specifically linked to the overuse of medical services, including emergency department visits, hospitalizations, diagnostic tests, laboratory tests, and pharmacy costs.⁹ Thus, GAD is a highly prevalent psychiatric disorder with significant morbidity, which particularly affects individuals who are unmarried, are a racial minority, and are in low socioeconomic strata.

Clinical Presentation

GAD is the most common anxiety disorder presenting to primary care physicians (PCPs). The clinical criteria are presented in Table 1.¹⁰ The condition is chronic and typically exhibits a waxing and waning pattern over time. Patients most commonly present with somatic complaints, such as headache, muscle pain, insomnia, fatigue, and restlessness. Fewer than 20% of GAD patients will present with psychological complaints.¹¹ The DSM-IV¹⁰ requires the presence of symptoms for ≥6 months, although the disorder evolves over a much longer time period for most patients. Frequently, a diagnosis of GAD is only made 5–10 years after the onset of symptoms. Population studies have found that the onset of GAD is common prior to 25 years of age, although there is a strong incidence of increase in GAD between 35–45 years of age.¹² GAD is commonly associated with chronic physical conditions that reduce the likelihood that it will be recognized correctly, which eventually will worsen the patient’s prognosis for GAD. The NCS study concluded that risk factors for GAD include female sex, being unmarried, and unemployment.¹³ Other conclusions of this study also showed that urban living, education, income, and religion are not significantly associated with GAD.¹³

Patients presenting with GAD will often report disturbances in three major domains: motor tension, autonomic hyperactivity, and hyperarousal. For example they may report poor sleep, poor concentration, tense muscles, or being “keyed-up” or “on edge” much of the time. Comorbidity with other anxiety disorders is common: patients frequently report pre-existing simple phobias, social phobia, panic disorder, or agoraphobia. There is a large overlap between GAD and other psychiatric disorders. Between 60% and 80% of patients with GAD report depression¹⁴ and over 80% report another anxiety disorder.¹⁵ It is also believed that GAD may precede MDD, dysthymia, and substance abuse, making it important to recognize as a “gateway” disorder. Therefore, a thorough evaluation for comorbid conditions is essential to treatment. It is recommended that PCPs screen for GAD symptoms, especially if a patient has repeated somatic complaints and has risk factors. If comorbidities are present, psychiatric consultation is advisable.

Psychotherapy for GAD focuses on relaxation training, breathing techniques, biofeedback, and cognitive-behavioral therapy (CBT, reframing patterns of thinking and/or controlled exposure to anxiety-provoking situations). The treatment should be tailored to the individual response and disposition of the patient. Medication approaches are indicated in moderate-to-severe cases less responsive to psychotherapy. Multiple medications have been used to treat GAD, including benzodiazepines, tricyclic antidepressants, and other antidepressants. However, trials with buspirone and selective serotonin reuptake inhibitors (SSRIs) show significant promise in treating anxiety associated with GAD.

Clinical Course

There is very little known about the long-term clinical course of GAD. One of the few prospective studies of GAD that has been carried out is the Harvard/Brown Anxiety Research Program (HARP), which recently published its 8-year follow-up data.¹⁶ In HARP, women with GAD continued remitting 8 years after initial entry into the study but experienced fewer overall remissions compared to men. Five-year follow-up HARP data consisted of 167 research subjects who had been diagnosed with GAD.¹⁵ Of these patients, full remission, defined by occasional or no symptoms for 8 consecutive weeks, was approximately 10% at 1 year (16% men, 10% women) and approximately 40% at 5 years (38% men, 35% women). Conversely, relapse in patients who had experienced a full remission was approximately 10% after 1 year and approximately 30% after 3 years. The relapse rate of those who had achieved partial remission, defined by worrying <50% of the time with three symptoms, was somewhat higher than for those patients that achieved full remission, probably due to unresolved underlying symptoms. Interestingly, the remission rates for panic disorder and social phobia were lower, indicating better response to interventions for GAD. In summary, the HARP study estimated that 40% of patients who were diagnosed with GAD reported an illness duration >5 years, which paralleled the findings of the ECA study.²

Factors associated with predicting a lower likelihood of full remission included a worse overall satisfaction with life and poorer quality of relationships with spouses and relatives. In contrast with other studies, HARP found that age of onset, length of illness, male gender, marital and socioeconomic status,¹² general medical health, comorbid MDD, dysthymia, posttraumatic stress disorder, OCD, social phobia, or panic disorder did not predict the length of an episode.¹⁶

Obsessive-Compulsive Disorder

Epidemiology

OCD is the fourth most common psychiatric disorder according to the ECA survey, with a lifetime prevalence ranging from 1.9% to 3.3% across the five sites.¹⁷ Before ECA, OCD was thought to be uncommon, as OCD patients often dissemble and conceal their symptoms, even from relatives. Childhood OCD is a chronic and underrecognized psychiatric condition that affects £2% to 3% of children and adolescents.^18,19 When adults with OCD are interviewed, £85% report childhood onset of symptoms,²⁰ suggesting early neurobiological mechanisms in OCD. Although classified as an anxiety disorder, OCD may be pathophysiologically unique due to its possible neurodevelopmental basis associated with basal ganglia dysfunction.²¹ OCD usually co-occurs with other anxiety and mood disorders, including GAD, panic disorder, social phobia, MDD, anorexia nervosa, trichotillomania, and personality disorders, such as obsessive-compulsive personality disorder, avoidant personality disorder, and dependent personality disorder.²² In children, there is a high incidence of Tourette’s syndrome or tic disorder associated with OCD.²³

Clinical observation suggests that most individuals with GAD will not have concurrent OCD; however, many individuals with OCD may have concurrent GAD. Furthermore, when etiology is considered, a family study¹³ of OCD found that relatives of patients with OCD had increased rates of GAD, a finding that could not be explained by the presence of OCD in relatives. A common genetic substrate was supported for OCD and GAD.²⁴ No other anxiety disorders showed this specificity with OCD.

In summary, OCD is a common but treatable psychiatric disorder of possible neurodevelopmental origin that affects >5 million Americans and has an economic impact of $8.4 billion per year.²⁵ It has a high frequency of comorbidity, especially with anxiety disorders and MDD.

Clinical Presentation

An obsession is an intrusive unwanted mental event usually evoking anxiety or discomfort. It can include thoughts, images, or urges and have religious, aggressive, or sexual content. Compulsions are ritualistic behaviors that allay fears from obsessive thoughts, although they may occur independently of obsessions. Compulsive behaviors typically include excessive washing and/or cleaning, ordering, checking, counting, hoarding, or touching.

Washing, checking, and counting compulsions were found to be the most common in DSM-IV¹⁰ OCD field trials.²⁶ In children, the most common OCD manifestation is handwashing, followed by repeating rituals and checking.²⁷

The clinical presentation of OCD is characterized by recurrent obsessions and compulsions, which are time consuming (ie, consume >1 hour per day) and cause marked distress or significant impairment in family, social, or occupational (and school) functioning.

Most adults have insight that the obsessions and compulsions are excessive, while a smaller number may not consider them excessive (the poor insight subtype). Younger children may lack insight into the severity or nature of obsessions and compulsions and insight is not required for the diagnosis of OCD in children.²⁸

Over 90% of patients can have features of both obsessions and compulsions, 28% are bothered by mainly obsessions, 20% by compulsions, and 50% by both.²⁶ While the DSM-IV¹⁰ does not recognize subtypes of OCD, the ICD-10⁶ classifies patients with OCD as predominantly obsessive, predominantly compulsive, or combined. Clinical criteria as defined by the DSM-IV¹⁰ are laid out in Table 2.

Factor analysis of OCD symptoms has repeatedly shown a four-factor structure: (1) aggressive obsessions (eg, dealing with sex, aggression, or religion); (2) contamination-cleaning; (3) order and/or symmetry; and (4) hoarding.^29,30 A predominantly obsessive form of OCD may result when the first two factors (aggressive obsessions and contamination-cleaning) occur together, while the last two factors (order-symmetry and hoarding) may describe a predominantly compulsive type of OCD. OCD of high severity often includes the four factors, but all combinations are possible in clinical practice.

OCD is classified among the anxiety disorders. This classification responds to the clinical observation that anxiety accompanies the experience of intrusive, unwanted (obsessive) thoughts and the need to perform behaviors in a rigid manner, often in response to obsessions. In children, there may not be a strong cognitive component to OCD and compulsive behaviors can be evident without child-reported anxiety.³¹ For example, younger boys will sometimes present with touching and other sensory compulsions that need to be performed until a “just right” feeling is achieved. These boys will sometimes also have motor and/or vocal tics and attention-deficit difficulties but little insight into the compulsions. Other types of anxiety, most notably separation anxiety or generalized forms of anxiety, are also commonly reported by children. Adults mostly present with impairing obsessions and compulsions that have been accommodated by relatives and to which the patient has yielded over time. These compulsions are performed if possible outside the recognition of coworkers and relatives. A childhood onset of symptoms is common, although frank disorder may not be present in childhood.

Clinical Course

The clinical course of OCD usually consists of subclinical symptoms early in life, which later manifest as clinically impairing obsessions and compulsions in adolescence or early adulthood. OCD can symptomatically wax and wane or become chronic and unrelenting. Exacerbations, sometimes dramatic, can occur in children and adolescents. For example, a longitudinal follow-up³² of 47 children with OCD revealed an average of 0.6 exacerbations per patient per year. In adults, waxing and waning is common, with relapse a frequent occurrence. In a study of 66 adult patients with OCD,³³ the probability of full remission from OCD over a 2-year period was 12% and the probability of partial remission was 47%. After achieving remission from OCD, the probability of relapse was 48%.³³ No factors were identified that significantly predicted full or partial remission.

In an unusually lengthy follow-up³⁴ of the course of OCD (mean length follow-up: 47 years), improvement was observed in 83% of subjects, including recovery in 48% (complete recovery: 20%; recovery with subclinical symptoms: 28%). Almost half of those who recovered did so in the first years of follow-up, while another half had OCD for >30 years. In this extensive series, the following were risk factors for worse outcome: early age at onset, presence of both obsessions and compulsions, and lower social functioning.³⁴ It is possible that early treatment of OCD, especially if presenting in childhood, may improve the course of the disease and decrease long-term relapse rates.

Using drugs that modulate serotonergic and dopaminergic brain neurotransmitter systems, effective psychopharmacologic treatments for OCD have been developed in recent years using predominantly SSRIs and clomipramine in children³⁵ and adults.³⁶ CBT has also emerged as an effective treatment both in children³⁷ and adults.³⁸ Therefore, for moderate-to-severe cases of OCD, a combination of CBT and medication is preferred, while in mild cases CBT is a preferred option.

GAD and OCD Phenomenology and Differential Diagnosis

Clinical Differences Between Worrying and Obsessions

The cardinal symptom of GAD is excessive worrying. Worry can consist of linked thoughts and images which contain negative affect and are hard to control.³⁹ While worry can constitute a problem-solving exercise, negative outcomes are prominent in the worrying process. Often realistic health, family, finance, and work problems are topics of worry in GAD.

OCD is characterized by obsessions and compulsions. Obsessions are always intrusive and usually senseless and even repugnant; they are often unrealistic in their extent and scope and can cause excessive worrying. Obsessional topics concern aggression, sexuality, religion, contamination, and sometimes doubt over events. The power of obsessions lies in that “thinking” can be equated with “happening”: the obsessional thought or image provokes the experience of a feeling which is equated to the actual dreaded event actually occurring. This “thought-action” fusion process characterizes many anxiety states but probably obsessions in particular.³⁹ This process is significantly different from GAD; individuals with GAD do not believe their thoughts can influence events. The obsession thus brings about a chain of events that includes an interpretation of the obsessional content, a fear related to it, and a behavioral consequence, such as a compulsive behavior (eg, handwashing in contamination fears).⁴⁰

Clinically, excessive worrying over daily life problems can accompany the presence of obsessions and compulsions, making GAD a frequent comorbid condition in patients with OCD. While worrying may be a surface symptom in OCD, so that obsessions underlie the worries, worrying is the cardinal symptom of GAD.

Differential Diagnosis of GAD and OCD

The epidemiology, clinical presentation, and clinical course of GAD and OCD appear as distinct. GAD is predominant in females and consists of everyday life worries that are difficult to control and cause somatic complaints. OCD is equally distributed in males and females and consists of obsessions and compulsions that are clinically impairing.

Both GAD and OCD may be difficult to detect in clinical settings. Patients with GAD can present initially to primary care settings with somatic complaints, where the use of medical services may be costly. However, a lifetime anxiety disorder has also been associated with the presence of cardiac and other medical illnesses; thus, the overlap between physical and mental illness should be carefully considered.⁴¹ Patients with OCD often engage in rituals secretively and obsessions are not reported to others, sometimes because they are fearful of “being thought crazy.” Careful clinical inquiry of GAD requires differentiating physical and mental symptoms in the primary care setting, with statements such as “Do you feel on edge, or uptight a lot?” or “Do you have trouble getting to sleep because of worries, or do you feel tired a lot from worrying so much?” Assessment of OCD should make the symptoms normative and can include questions such as “Some patients have thoughts they cannot get out of their heads; for example, they feel their hands are dirty, no matter how much they wash them. Do you ever experience this?” Questioning needs to be methodical and validating of the symptomatic experience in order to avoid defensive postures of the patient. In GAD, a pitfall exists in that the patient may consider the questions a minimization of their physical discomfort. In OCD, the lack of easy disclosure of obsessions and compulsions that are embarrassing to the patient may make it difficult for the clinician to obtain information.

From a clinical perspective, the anticipatory anxiety over everyday tasks, competence, self-evaluation (ie, performance), and perception by others of the individual with GAD is distinct from the intrusive thoughts (ie, obsessions) of the individual with OCD, but the differences may not be clear on first questioning. For example, an individual may have intrusive images of attacking a relative, which is only manifest as worries over the safety of his or her family. Deeper inquiry is required to understand whether an obsessive thought underlies the overt worries. Additionally, some individuals with depression tend to ruminate (ie, “get stuck” on some unpleasant thought or prospective unwanted outcome). Daily worrying (in GAD), intrusive obsessions (in OCD), and rumination (secondary to depression) can usually be differentiated with systematic questioning. Table 3 summarizes distinctive features of GAD and OCD for comparison purposes.

Conclusion

Patients with GAD will present with anticipatory worrying or anxious apprehension that is difficult to control, and may possibly be accompanied by bodily complaints. They might focus on somatic issues and not consider the psychological burden a primary complaint. Refocusing the interview toward an understanding of the (physical) consequences of increased worrying can direct the patient to reveal an extensive history of lifetime excessive worrying. Patients with OCD present to clinic for unusual complaints, such as dry hands from excessive handwashing, bleeding gums from excessive toothbrushing, or inability to concentrate or sleep from disturbing obsessions. They are often reluctant to seek psychiatric consultation unless the disease is advanced, and only sensitive questioning may reveal OCD symptoms. They may report worrying over safety or concerns with competence; however, obsessions and compulsions are the underlying cause of these worries. GAD is furthermore highly associated with OCD, possibly masking the underlying obsessions.

A common emphasis for the clinician in diagnosing these disorders should be that only careful and sensitive inquiry can elicit the information on and differentiate excessive worrying, obsessions, and compulsions. A stepwise approach would include: (1) assessing physical symptoms and ruling out an organic cause for the physical complaint; (2) ascertaining the presence of anxiety, apprehension, and worries; (3) leaning toward a diagnosis of GAD if the anxiety reflects anticipatory worrying over daily life events and perception by others; and (4) leaning toward a diagnosis of OCD if the anxiety has a single area of focus related to an overvalued belief (eg, contamination from touching walls) and is possibly associated with intrusive thoughts (ie, obsessions). PP

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