Obsessive-Compulsive Disorder and Common Comorbidities

Charles F. Brady, PhD, ABPP

Lindner Center of HOPE and Lindner Center Professional Associates, Mason, Ohio, and the Department of Psychiatry, University of Cincinnati and University of Cincinnati Physicians, Cincinnati, Ohio

AV 1. Prevalence of Comorbid Psychiatric Disorders in Patients With OCD (00:24)

The eating disorder rates reflect lifetime comorbidity
Abbreviations are defined before the References

Patients with OCD have high rates of comorbidity of other psychiatric disorders (AV 1).1–6 In one OCD specialty clinic sample,7 for example, 57% of patients had concurrent psychiatric diagnoses. Challenges arise in providing treatment for patients who have OCD and additional psychiatric conditions.

OCD and Mood Disorders

Prevalence and impact. For the patient with OCD, the occurrence of a major depressive episode is an all-too-common phenomenon. Up to two-thirds of adults with OCD have experienced MDD during the course of their illness, and, when presenting for treatment, about one-third of patients with OCD have concurrent MDD.7 Typically, OCD symptoms precede the onset of the depression.7

In a recent study of 815 patients with OCD, Quarantini and colleagues8 confirmed what is observed in clinical practice, ie, the patient with OCD and comorbid depression presents with more severe impairment and symptoms than the patient with only OCD. Individuals with OCD develop learned helplessness in their often futile attempts to suppress the intrusive thoughts inherent to the condition. Their symptoms and distress may also promote excessive avoidant behavioral patterns that lead to increased losses of positively reinforcing experiences and result in subsequent dysphoria.

In addition to MDD, many individuals with OCD have bipolar disorder. Angst and colleagues3 found that 53% of patients with OCD had hypomanic symptoms, with 30% meeting diagnostic criteria for bipolar II disorder. Timpano and coworkers2 found a lower prevalence of 13% for bipolar illness in patients with OCD. Among patients with bipolar disorder, 7% to 21% had comorbid OCD.2 Overall, OCD appears to be more prevalent among individuals with bipolar II disorder than among those with bipolar I disorder.9 Evidence9 suggests that, for those with OCD and comorbid bipolar disorder, the OCD symptoms appear earlier than in patients with only OCD. Individuals with OCD and comorbid bipolar disorder appear to be at higher risk for co-occurring substance abuse than those with only OCD,10 and they may also have fewer compulsions.9 Although both groups typically have an equal number of obsessions, the individuals with bipolar disorder and OCD are more likely to have obsessions that are existential, superstitious, or philosophical.9

Treatment. The recommended first-line treatment for adults with mild OCD is CBT, and adjunctive SRIs are recommended for moderate-to-severe OCD.11 Experts consider exposure and response prevention (ERP), a behavioral therapy, to be the best form of psychotherapy for patients with OCD.11 By enduring repeated exposure to a feared stimulus, patients’ anxiety about the stimulus decreases and they can avoid performing their ritualized response to it. Experts suggest that supplementing ERP with cognitive therapy can improve adherence and target distorted beliefs.11

To treat OCD and comorbid depression, expert consensus guidelines11 recommend combined CBT and SRIs as first-line treatment. Observations from clinical practice suggest that, if the OCD and depression are mild and the depressive symptoms appear to be caused by the OCD symptoms, CBT alone could be used as a first-line intervention. However, clinical judgment may be necessary to discern whether depressive symptoms are interfering with the patient’s ability to participate effectively in ERP, in which case pharmacologic treatment and CBT should target the depression. Overall, clinical experience concurs with recent empirical evidence1,12 that treatment for OCD will also yield successful reduction of depressive symptoms. For the clinician treating the patient with OCD and comorbid bipolar disorder, using mood-stabilizing medications in addition to the standard pharmacologic and psychotherapeutic approaches to treating OCD is imperative.11,13

OCD and Psychotic Disorders

Prevalence and impact. The presence of psychotic symptoms complicates the treatment of OCD. Bottas and colleagues14 reported that the rate of obsessive-compulsive symptoms (OCS) in individuals with schizophrenia ranges from 10% to 52% and the rate of diagnosable OCD ranges from 8% to 26%. In a study of 757 patients in an OCD specialty clinic, de Haan and colleagues4 found that almost 2% met diagnostic criteria for a psychotic disorder. In an older study5 of patients with OCD, as many as 12% were also diagnosed with schizophrenia.


For patients with schizophrenia and OCS, evidence suggests greater levels of cognitive deficits, negative and positive symptoms, neurologic soft signs, depression, suicidal ideation, and suicide attempts than for patients with only schizophrenia.15 Emerging data15 from neuroimaging studies indicate neuroanatomical differences between patients with combined schizophrenia and OCS and patients with either OCD or schizophrenia alone, and those with both schizophrenia and OCS show more impairment on neuropsychological tests.

Case Example. Mr A, a 26-year-old single man, has been diagnosed with both OCD and paranoid schizophrenia. He engages in 30 minutes of checking rituals at night to feel certain that he has turned off his lights and stove and locked his doors. Mr A also checks his apartment door and his car doors repeatedly before exiting. He believes that his neighbors are plotting to steal his identity, and he compulsively shreds his mail and re-reads all of his outgoing mail to protect himself. When Mr A discusses the reasons for checking his lights and stove, he speaks in terms of “not knowing for sure” if he can trust his knowledge of turning them off. When he expresses his belief about the plot to steal his identity, Mr A states that he knows it is “true” without any wavering or doubt.

This case illustrates the most significant differences between obsessions and delusions. The obsession about lights, stoves, and locks is characterized by the presence of uncertainty and fits a classic theme of hyper-responsibility that is common to many obsessions. On the contrary, the belief that others are conspiring to steal Mr A’s identity is held with extreme rigidity and reflects the persecutory theme that is common in paranoid delusions. 

Treatment. For the psychotherapist, CBT approaches can be implemented for both the OCD and the psychotic symptoms. For the prescribing physician, the presence of psychotic beliefs in addition to OCD indicates the need for antipsychotic medication in addition to the standard medication algorithm used for treating OCD.

OCD and Eating Disorders

Prevalence and impact. Studies16,17 of patients in intensive eating disorder programs suggest that rates of OCD range from 24% to 41%. In studies6 that have examined the prevalence of eating disorders in OCD populations, rates have ranged from 3% to 17%. Patients with eating disorders typically display ritualized behaviors that manifest in rigid schedules, eating habits, portion sizes, or ways food is ingested. Although ritualized, these behaviors are not considered OCD symptoms because they are directly related to concerns of weight loss and body image. However, individuals with eating disorders may experience obsessions and compulsions related to other core fears (eg, contamination, harm; AV 2).

AV 2. Examples of Eating Obsessions Unrelated to Body Image or Desire to Lose Weight (00:32)


Some people may exhibit an overlap between an eating disorder and OCD. For instance, individuals with anorexia and OCD may excessively count calories throughout the day with the hope of weight loss and the concurrent fear that, if they eat more than a specific number of calories, something bad may happen to them or a family member.

Others with only OCD may have obsessive fears of eating certain foods and avoid eating them. The avoidance of certain foods may expand to include increasingly more foods, leading to weight loss and malnourishment. Unlike patients with eating disorders, individuals with obsessive fears may have no desire to lose weight and no distortions of body image.

Treatment. The treatment of the individual with a comorbid eating disorder and OCD requires aggressive treatment of both conditions. The patient must have adequate BMI and nourishment to benefit from CBT. Inpatient hospitalization with emphasis on bolstering BMI and nourishment may be required. Pharmacotherapy with appropriate antidepressant medications is often necessary. Once a healthy weight is obtained and maintained, CBT using ERP for the OCS and targeting the underlying behaviors and distorted beliefs of body image will also be useful.


With medication and psychotherapy, OCD is a highly treatable condition, but it often presents with comorbid conditions that require additional treatment. The most common comorbid condition, depression, can be treated with CBT and, if needed, antidepressants, but the CBT may have to target the depression if depressive symptoms are interfering with OCD treatment. Comorbid bipolar disorder or schizophrenia should prompt the use of adjunctive mood stabilizers or antipsychotics. Patients with OCD and an eating disorder must be healthy enough for OCD treatment, and those who are not may require hospitalization to reach a safe BMI. Clinicians who are familiar with adjunctive options can successfully treat their patients with OCD and comorbid psychiatric disorders.

Clinical Points


  • Treat OCD and comorbid depression with CBT and antidepressant medication, particularly SRIs
  • Add mood stabilizers to standard OCD treatment for patients with OCD and comorbid bipolar disorder
  • Add antipsychotic medication and targeted CBT for patients with OCD and psychotic symptoms
  • Ensure that patients with OCD and an eating disorder have adequate BMI and nourishment for OCD treatment



BMI = body mass index, CBT = cognitive-behavioral therapy, ERP = exposure and response/ritual prevention, MDD = major depressive disorder, OCD = obsessive-compulsive disorder, OCS = obsessive-compulsive symptoms, SRI = serotonin reuptake inhibitor

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