Obsessive–Compulsive Disorder Versus Other Disorders

Obsessive–Compulsive Disorder Versus Other Anxiety Disorders

Both OCD and the other anxiety disorders are characterized by the use of avoidance to manage anxiety. However, OCD is distin-guished from these disorders by the presence of compulsions. For OCD patients with preoccupying fears or worries but no rituals, several other features may be useful in establishing the diagnosis of OCD. In social phobia and specific phobia, fears are circum-scribed and related to specific triggers (in specific phobia) or so-cial situations (in social phobia). Although circumscribed situa-tions may initially trigger obsessions and compulsions in OCD, triggers in OCD become more generalized over time, unlike the triggers in social and specific phobias, in which the evoking situ-ations remain circumscribed.

As many as 60% of people with OCD experience full-blown panic symptoms. However, unlike panic disorder, in which panic attacks occur spontaneously, panic symptoms occur in OCD only during exposure to specific feared triggers such as contaminated objects. The worries that are present in generalized anxiety dis-order (GAD) are more ego syntonic and involve an exaggeration of ordinary concerns, whereas the obsessional thinking of OCD is more intrusive, is limited to a specific set of concerns (e.g., contamination, blasphemy), and usually has an irrational, sense-less, or unreasonable quality. Also, whereas the worry of GAD is considered primarily thoughtlike in nature, obsessional symp-toms may consist of thoughts, impulses, or images.

Obsessive–Compulsive Disorder Versus Psychotic Disorders

One question is how to differentiate OCD from psychotic disorders such as schizophrenia and delusional disorder. An-other question is how to distinguish OCD with insight from OCD without insight (delusional OCD). One distinguishing feature between OCD and the psychotic disorders is that the latter are not characterized by prominent ritualistic behaviors. If compulsions are present in a patient with prominent psy-chotic symptoms, the possibility of a comorbid OCD diagnosis should be considered. Furthermore, although schizophrenia may be characterized by obsessional thinking, other character-istic features of the disorder, such as prominent hallucinations or thought disorder, are also present. With regard to delusional disorder, paranoid and grandiose concerns are generally not considered to fall under the OCD rubric. However, some other types of delusional disorder, such as the somatic and jealous types, seem to bear a close resemblance to OCD and are not always easily distinguished from it. It will be interesting to see whether future research indicates that certain types of so-matic delusional disorder (e.g., the delusional variant of hypo-chondriasis) and the jealous type of delusional disorder (also referred to as pathological jealousy) are actually variants of OCD.

The second issue noted above – how to distinguish OCD with insight from OCD without insight – is complex. As previ-ously discussed, insight in OCD is increasingly being recognized as spanning a spectrum from good to poor to absent. Both clini-cal observations and research findings indicate that some indi-viduals hold their obsessional concerns with delusional intensity and believe that their concerns are reasonable. In DSM-IV, delu-sional OCD may be double-coded as both OCD and delusional disorder or as both OCD and psychotic disorder not otherwise specified, in other words, patients with delusional OCD would receive both diagnoses. This double coding reflects the fact that it is unclear whether OCD with insight and OCD without insight constitute the same or different disorders. Further research using validated scales to assess insight in OCD is needed to shed light on this question.

Obsessive–Compulsive Disorder Versus Impulse Control Disorders

Differential diagnosis questions have been raised with regard to kleptomania, trichotillomania, pathological gambling and other disorders involving impulsive behaviors. Several features have been said to distinguish these disorders from OCD. For ex-ample, compulsions – unlike behaviors of the impulse control disorders – generally have no gratifying element, although they do diminish anxiety. In addition, the affective state that drives the behaviors associated with these disorders may differ. In OCD, fear is frequently the underlying drive that leads to com-pulsions, which, in turn, decrease anxiety. In the impulse control disorders, patients frequently describe heightened tension, but not fear, preceding an impulsive behavior. However, OCD and the impulse control disorders have some features in common. Re-search is ongoing to explore the relationship between OCD and the impulse control disorders by examining similarities and dif-ferences in treatment response, biological markers and familial transmission.

Obsessive–Compulsive Disorder Versus Tourette’s Disorder

Complex motor tics of Tourette’s disorder may be difficult to distinguish from OCD compulsions. Both tics and compulsions are preceded by an intrusive urge and are followed by feelings of relief. However, OCD compulsions are usually preceded by both anxiety and obsessional concerns, whereas, in Tourette’s disorder, the urge to perform a tic is not preceded by an obses-sional fear. This distinction breaks down to some extent when considering the “just right” perceptions of some patients with OCD. The “just right” perception refers to the need to perform a certain motor action, such as touching, tapping, checking, order-ing, arranging, or counting, until it feels right. Determining when an action has been performed enough or perfectly may depend on tactile, visual, or auditory perceptions. In a study of patients with Tourette’s disorder and OCD symptoms, most patients could distinguish between the mental urge to do something repeatedly until it felt right and a physical urge to perform a motor tic. How-ever, it is sometimes difficult for psychiatrists to distinguish be-tween complex tics and compulsions, especially when a patient has both disorders.

Obsessive–Compulsive Disorder Versus Hypochondriasis

Fears of illness that occur in OCD, referred to as somatic obses-sions, may be difficult to distinguish from hypochondriasis. Usu-ally, however, patients with somatic obsessions have other cur-rent or past classic OCD obsessions unrelated to illness concerns. Patients with OCD also often engage in classic OCD rituals, such as checking or reassurance seeking, in an attempt to diminish their illness concerns. Unlike patients with OCD, patients with hypochondriasis experience somatic and visceral sensations. Although insight and resistance have been used to distinguish OCD from hypochondriasis, with the concern in hypochondria-sis being said to be egosyntonic (realistic and totally justified) and that of OCD to be egodystonic (unacceptable and undesirable thoughts, actions, or both), studies have demonstrated a range of insight in OCD. Attempting to differentiate these disorders by degree of insight or egosyntonicity may therefore be of limited usefulness.

Obsessive–Compulsive Disorder Versus Body Dysmorphic Disorder

Body dysmorphic disorder (BDD), a preoccupation with an im-agined or slight defect in appearance (e.g., thinning hair, facial scarring, or a large nose), has many similarities to OCD (Phillips, 1991). Patients with BDD experience obsessional thinking about the supposed defect and usually engage in associated repetitive ritualistic behaviors, such as mirror checking and reassurance seeking. Preliminary evidence suggests that BDD also appears similar to OCD in terms of age of onset, course of illness and other variables. Nonetheless, emerging data suggest that there are some important differences between the two disorders, and they are currently classified separately in DSM-IV. Insight, for example, is more frequently impaired in BDD than in OCD. If the content of a patient’s obsessions involves a concern about a supposed defect in appearance, BDD, rather than OCD, is the diagnosis that should be given.

Obsessive–Compulsive Disorder Versus Obsessive–Compulsive Personality Disorder

Obsessive–compulsive personality disorder is a lifelong mala-daptive personality style characterized by perfectionism, exces-sive attention to detail, indecisiveness, rigidity, excessive devo-tion to work, restricted affect, lack of generosity and hoarding. OCD and OCPD have historically been considered variants of the same disorder on a continuum of severity, with OCD viewed as the more severe manifestation of illness. Contrary to this notion, studies using structured interviews to establish diagnosis have found that not all patients with OCD also have OCPD. One rea-son for the perception that these disorders are linked lies in the frequency of several OCPD traits in patients with OCD. In one study, the majority of 114 patients with OCD had perfectionism and indecisiveness (82 and 70, respectively). In contrast, other OCPD traits, such as restricted affect, excessive devotion to work and rigidity, were seen infrequently.

Although perfectionism and indecisiveness are relatively common traits in patients with OCD, the distinction between OCD and OCPD is important, and several guidelines may be useful in distinguishing them. Unlike OCPD, OCD is character-ized by distressing, time-consuming egodystonic obsessions and repetitive rituals aimed at diminishing the distress engendered by obsessional thinking. One of the hallmarks that traditionally has been used to distinguish OCD from OCPD is that, in con-trast, OCPD features are considered egosyntonic. In addition, as previously noted, the traits of restricted affect, excessive devo-tion to work and rigidity are generally characteristic of OCPD but not OCD. Although useful, these guidelines are not absolute, and some patients defy easy categorization. Some patients, for example, spend hours each day engaged in egosyntonic behav-iors such as excessive cleaning; such patients may seek treatment not because they are disturbed by their behaviors but because the behaviors cause problems in functioning or family friction. It is unclear whether some of these patients should be diagnosed with OCPD or subthreshold OCD.

Obsessive–Compulsive Spectrum Disorders

Certain disorders other than OCD, such as BDD, hypochondria-sis, and eating disorders, are characterized by obsessional think-ing and/or ritualistic behaviors. On the basis of these apparent similarities with OCD, the concept of OCD spectrum disorders has been developed. They have been defined as disorders that share features with OCD (Hollander, 1993) and are posited to have “spectrum membership” on the basis of their similarities with OCD across multiple domains. These domains include not only symptoms but also treatment response, comorbidity, joint familial loading, sex ratio, age at onset, course, premorbid per-sonality characteristics and presumed cause. Cause is inferred from characteristics such as neurological deficits, response to bi-ological challenges, biochemical indices, brain imaging patterns (functional and anatomical) and epidemiological risk factors. It is worth noting that there are currently no operational criteria for what constitutes an OCD spectrum disorder; for example, in which of the preceding domains must similarities be documented, and how similar in each domain must the disorder be to OCD?

Disorders postulated to be OCD spectrum disorders in-clude BDD, hypochondriasis, eating disorders, “grooming” dis-orders such as nail biting and trichotillomania, and the impulse

disorders (see Figure 51.3). Of interest is a recent study investi-gating the frequency of these disorders in first-degree relatives of people with OCD. BDD, hypochondriasis, any eating disorder (although not anorexia or bulimia individually) and grooming disorders (but not the impulse control disorders) were found more frequently in probands with OCD than in general population con-trols. In addition, BDD and grooming disorders (although not the other disorders) were significantly more common in the first-degree relatives of OCD probands than in relatives of controls (Bienvenu et al., 2000). This finding suggests that certain of the proposed OCD spectrum disorders may have a familial link to OCD. The relationship of these disorders with OCD is an area in which exciting research will be conducted in coming years.