Is obsessive–compulsive disorder an anxiety disorder?

doi:10.1016/j.pnpbp.2005.11.003

Progress in Neuro-Psychopharmacology and Biological Psychiatry

Volume 30, Issue 3, May 2006, Pages 338-352

https://doi.org/10.1016/j.pnpbp.2005.11.003 Get rights and content

Abstract

Obsessive–compulsive disorder (OCD) is classified as an anxiety disorder in the DSM-IV-TR [American Psychiatric Association, 2000. Diagnostic and statistical manual of mental disorders, Fourth ed., rev. Washington, DC: Author]; however, the notion of a spectrum of obsessive–compulsive (OC) related disorders that is comprised of such disparate disorders as OCD, body dysmorphic disorder, certain eating disorders, pathological gambling, and autism, is gaining acceptance. The fact that these disorders share obsessive–compulsive features and evidence similarities in patient characteristics, course, comorbidity, neurobiology, and treatment response raises the question of whether OCD is best conceptualized as an anxiety or an OC spectrum disorder. This article reviews evidence from comorbidity and family studies, as well as biological evidence related to neurocircuitry, neurotransmitter function, and pharmacologic treatment response that bear on this question. The implications of removing OCD from the anxiety disorders category and moving it to an OC spectrum disorders category, as is being proposed for the DSM-V, is discussed.

Introduction

Obsessive–compulsive disorder (OCD) is currently classified as an anxiety disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM) (American Psychiatric Association, 2000). Indeed, throughout most of the twentieth century, OCD has been viewed as an anxiety disorder or neurosis (Tynes et al., 1990). However, the notion of a spectrum of obsessive–compulsive (OC) related disorders that is comprised of such disparate disorders as OCD, body dysmorphic disorder, certain eating disorders, pathological gambling, and autism, is gaining acceptance. The fact that these disorders share obsessive–compulsive features and evidence similarities in patient characteristics, course, comorbidity, neurobiology, and treatment response raises the question of whether OCD is best conceptualized as an anxiety disorder or as part of an OC spectrum of disorders. In this article, we evaluate evidence from comorbidity and family studies, as well as biological evidence related to neurocircuitry, neurotransmitter function, and pharmacologic treatment response that bear on this issue. Because other articles in this issue cover the OC spectrum in detail, we will focus primarily on similarities and differences between OCD and other anxiety disorders and will be less concerned with research related to the OC spectrum (the reader is also referred to Hollander et al., 2005a, for an in-depth discussion of the OC spectrum). We conclude with a discussion of the implications of removing OCD from the anxiety disorders category and moving it to an OC spectrum disorders category, as is being proposed for the DSM-V.

Section snippets

The current nosology of obsessive–compulsive disorder

OCD is a debilitating disorder marked by two distinct phenomena: recurrent, disturbing, intrusive thoughts (obsessions) and overt repetitive behaviors or mental acts (compulsions) that are performed to reduce distress caused by obsessions. The most common obsessions concern thoughts about contamination, pathological doubt, and order/symmetry (Eisen and Rasmussen, 2002). Other obsessions include sexual obsessions as well as concerns about aggressive or horrific impulses (e.g., hurting a loved

The obsessive–compulsive spectrum disorders

In the past two decades the notion of an OC spectrum of related disorders has gained popularity (Hollander, 1993, Hollander et al., 2005a, Jenike, 1990, McElroy et al., 1994, Stein, 2002). The OC spectrum was proposed in response to observations that a number of disparate disorders, for example, body dysmorphic disorder, hypochondriasis, some eating disorders, and some impulse control disorders, share obsessive–compulsive features—that is, they are marked by obsessive thinking and/or compulsive

Is OCD an anxiety disorder? Comorbidity studies

One way to demonstrate a relationship between two disorders is to show that patients with disorder A are more likely to have disorder B and, conversely, that patients with disorder B are more likely to have disorder A; however, when evaluating comorbidity patterns it is important to consider whether the comorbid disorder is a long-term complication of the primary disorder.

Is OCD an anxiety disorder? Family studies

In addition to showing evidence of high comorbidity rates, a unique relationship between OCD and one or more other disorders would be supported by evidence showing increased prevalence of the disorder(s) in relatives of patients with OCD.

The neurocircuitry of OCD

Drawing upon functional neuroimaging data and earlier theorizing, Saxena and Rauch (2000) put forward a model for the pathophysiology of OCD that points to dysfunction in orbitofrontal–subcortical circuitry. This circuitry is thought to be comprised of a direct and an indirect pathway, both of which originate in the frontal cortex and project to the striatum. From the striatum, however, the direct pathway projects to the globus pallidus interna/substantia nigra, pars reticulate (GPi/SHr)

Is OCD an anxiety disorder? Neurotransmitter function and pharmacologic treatment response

A number of neurotransmitter systems have been implicated in anxiety disorders, in particular monoaminergic transmitters (i.e., norepinephrine, serotonin, and dopamine), amino acid transmitters (i.e., gamma aminobutyric acid (GABA) and glutamate), and peptidergic neurotransmitters (i.e., corticotrophin releasing hormone (CRH), neuropeptide Y, and substance P) (Charney, 2003). Evidence for the role of specific neurotransmitters is supported by neurochemical, pharmacologic, and neuroimaging

Commentary

In an effort to clarify the relationship between OCD and other anxiety disorders, including PTSD, panic disorder, specific and social phobia, and GAD, this article reviewed comorbidity and family studies as well as studies investigating neurocircuitry, neurotransmitter function, and treatment response. Studies investigating comorbidity patterns between OCD and other anxiety disorders are mixed: some suggest increased prevalence rates for current and lifetime anxiety disorders in OCD, whereas

Implications of changing OCD classification in the DSM-V

It is currently being proposed that OCD be removed from the anxiety disorders category in the DSM-V and clustered with other putative OC spectrum disorders. Removing OCD from the anxiety disorders category will likely highlight the distinct features of OCD and, hopefully, raise awareness about OCD, increasing the likelihood of detection and appropriate treatment. It is believed that many OCD cases go undetected because patients are embarrassed about their symptoms and, consequently, are

Acknowledgements

Preparation of this chapter was supported by grants from the National Institute of Mental Health, National Institute on Neurological Disorders and Stroke, National Institute on Drug Abuse, Food and Drug Administration and investigator initiated research grants from Solvay, Wyeth, Pfizer, and Ortho-McNeil.

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Review articleIs obsessive–compulsive disorder an anxiety disorder?

Abstract

Introduction

Section snippets

The current nosology of obsessive–compulsive disorder

The obsessive–compulsive spectrum disorders

Is OCD an anxiety disorder? Comorbidity studies

Is OCD an anxiety disorder? Family studies

The neurocircuitry of OCD

Is OCD an anxiety disorder? Neurotransmitter function and pharmacologic treatment response

Commentary

Implications of changing OCD classification in the DSM-V

Acknowledgements

J Psychiatr Res

Eur J Pharmacol

Biol Psychiatry

Biol Psychiatry

Compr Psychiatry

Biol Psychiatry

Psychiatry Res

Biol Psychiatry

J Affect Disord

Compr Psychiatry

Eur Neuropsychopharmacol

Behav Brain Res

Neurosci Biobehav Rev

Biol Psychiatry

Brain Dev

Neuron

Compr Psychiatry

Prog Neuropsychopharmacol Biol Psychiatry

Psychiatry Res

Psychiatry Res

Biol Psychiatry

Psychiatry Res

Biol Psychiatry

Biol Psychiatry

Compr Psychiatry

Psychiatry Res

Psychiatr Clin North Am

Biol Psychiatry

Psychiatry Res

NeuroImage

Psychoneuroendocrinology

Biol Psychiatry

J Anxiety Disord

Brain Res

Patients with obsessive–compulsive disorder have increased 5-HT2A receptor binding in the caudate nuclei

Int J Neuropsychopharmacol

Diagnostic and statistical manual of mental disorders

Pathological gambling in two patients on dopamine replacement therapy for Parkinson's disease

Neurol Sci

Morbidity risk for obsessive–compulsive spectrum disorders in first-degree relatives of patients with eating disorders

Am J Psychiatry

Altered dopamine function in pathological gambling

Psychol Med

fMRI reveals amygdala activation to human faces in social phobics

NeuroReport

Cerebral glucose metabolism in women with panic disorder

Am J Psychiatry

Psychiatric disorders in relatives of probands with obsessive–compulsive disorder and co-morbid major depression or generalized anxiety

Psychiatr Genet

Pathological gambling and platelet MAO activity: a psychobiological study

Am J Psychiatry

Pathological gambling and obsessive–compulsive spectrum disorders

Psychol Rep

Enhanced sensitivity to cholecystokinin tetrapeptide in panic disorder. Clinical and behavioral findings

Arch Gen Psychiatry

The panicogenic effects of cholecystokinin-tetrapeptide are antagonized by L-365,260, a central cholecystokinin receptor antagonist, in patients with panic disorder

Arch Gen Psychiatry

Functional magnetic resonance imaging of symptom provocation in obsessive–compulsive disorder

Arch Gen Psychiatry

Current and lifetime comorbidity of the DSM-IV anxiety and mood disorders in a large clinical sample

J Abnorm Psychol

Linkage analysis for autism in a subset of families with obsessive–compulsive behaviors: evidence for an autism susceptibility gene on chromosome 1 and further support for susceptibility genes on chromosome 6 and 19

Mol Psychiatry

Anxiety and major depression comorbidity in a family study of obsessive–compulsive disorder

Depress Anxiety

Review article
Is obsessive–compulsive disorder an anxiety disorder?