The involvement of the orbitofrontal cortex and dorsolateral prefrontal cortex in OCD is shared with bipolar disorder, and may explain the high degree of comorbidity. Decreased volumes of the dorsolateral prefrontal cortex related to executive function has also been observed in OCD.People with OCD evince increased grey matter volumes in bilateral lenticular nuclei, extending to the caudate nuclei, with decreased grey matter volumes in bilateral dorsal medial frontal/anterior cingulate gyri. These findings contrast with those in people with other anxiety disorders, who evince decreased (rather than increased) grey matter volumes in bilateral lenticular/caudate nuclei, as well as decreased grey matter volumes in bilateral dorsal medial frontal/anterior cingulate gyri. Increased white matter volume and decreased fractional anisotropy in anterior midline tracts has been observed in OCD, possibly indicating increased fiber crossings. Cognitive models
Generally, two categories of models for OCD have been postulated. The first category involves deficits in executive dysfunction and is based on the observed structural and functional abnormalities in the dlPFC, striatum and thalamus. The second category involves dysfunctional modulatory control and primarily relies on observed functional and structural differences in the ACC, mPFC, and OFC.One proposed model suggests that dysfunction in the OFC leads to improper valuation of behaviors and decreased behavioral control, while the observed alterations in amygdala activations leads to exaggerated fears and representations of negative stimuli.Due to the heterogeneity of OCD symptoms, studies differentiating various symptoms have been performed.
ACT uses acceptance and mindfulness strategies to teach patients not to overreact to or avoid unpleasant thoughts and feelings but rather "move toward valued behavior. "A 2007 Cochrane review found that psychological interventions derived from CBT models, such as ERP and ACT, were more effective than non-CBT interventions. Other forms of psychotherapy, such as psychodynamics and psychoanalysis, may help in managing some aspects of the disorder. However, in 2007, the American Psychiatric Association (APA) noted a lack of controlled studies showing their efficacy, "in dealing with the core symptoms of OCD." For body-focused repetitive behaviors (BFRB), behavioral interventions such as habit-reversal training and decoupling are recommended.Psychotherapy in combination with psychiatric medication may be more effective than either option alone for individuals with severe OCD. ERP coupled with weight restoration and serotonin reputake inhibitors has proven the most effective when treating OCD and an eating disorder simultaneously. Medication
The medications most frequently used to treat OCD are antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs). Clomipramine, a medication belonging to the class of tricyclic antidepressants, appears to work as well as SSRIs, but has a higher rate of side effects.SSRIs help people with OCD by inhibiting the reabsorption of serotonin by the nerve cells after they carry messages from neurons to synapse; thus, more serotonin is available to pass further messages between nearby nerve cells.SSRIs are a second-line treatment of adult OCD with mild functional impairment, and as first-line treatment for those with moderate or severe impairment.