Applying factor analysis, researchers sought to reduce a wide range of obsessive-compulsive symptoms to a smaller number of categories. To date, 11 factor analysis studies assessing more than 2000 patients have consistently identified 4 principal OCD symptom dimensions that account for almost 70% of the variance.17
- Factor 1: aggressive and sexual obsessions and related compulsions.
- Factor 2: symmetry, ordering, and counting obsessions and compulsions.
- Factor 3: contamination obsessions and cleaning compulsions.
- Factor 4: hoarding obsessions and compulsions.
These symptom dimensions are relatively stable over time and show different patterns of genetic inheritance, age of onset, comorbidity, and treatment response.11 Compared with other patients with OCD, compulsive hoarders have an earlier age at onset, greater prevalence of symmetry, ordering and counting compulsions, lower insight, and older age when presenting for treatment.18 Interestingly, in the Collaborative Genetic Study, the hoarding phe-notype had the strongest familial rela- tionship of the OCD symptom factors, with robust correlation among sibling pairs.19
Early studies investigating the influence of OCD symptom factors on treatment response found that hoarding symptoms were associated with poor response to SRIs. However, a recent prospective trial of paroxetine(Drug information on paroxetine) did not find any difference between patients with hoarding OCD versus non-hoarding OCD.20 Hoarding has consistently been associated with poor response to cognitive-behavioral therapy (CBT).18 Multimodal treatment combining pharmacotherapy, including SRI-antipsychotic combination, intensive daily CBT, and psychosocial rehabilitation achieved meaningful improvement of hoarding symptoms.21 However, the response of hoarders to intensive intervention was less robust than that of non-hoarders, as reflected by a significantly smaller reduction in Y-BOCS scores (P = .02). A substantial proportion of patients with OCD who had a predominant hoarding phenotype had poor insight, which is associated with schizotypal personality disorder (SPD).22 The hoarding syndrome has also been consistently observed in patients with schizophrenia. Explicit evaluation of the role of antipsychotic augmentation in the hoarding OCD subtype is yet to be performed.Schizotypal-related OCD phenotype
SPD shares common phenomenological and neurobiological characteristics with schizophrenia and aggregates in patients who have OCD at a rate that extends random epidemiological comorbidity.23 Studies are consistent in demonstrating that patients who have OCD and associated schizotypal personality disorder exhibit a more deteriorative course and poorer prognosis than those with "pure" OCD.23 In addition, early age at onset, male sex, counting compulsions, and a history of specific phobia substantially increased the odds of schizotypy in patients with lifetime OCD. Preliminary evidence indicates that the presence of schizotypal personality disorder predicts poor response to standard pharmacological (eg, SSRIs) and behavioral intervention in OCD patients.23 The addition of low-dose antipsychotic agents (pim-ozide and olanzapine(Drug information on olanzapine)) to SSRIs has been found to be efficacious in some studies.24,25
The findings of a recently completed study comparing patients who have DSM-IV OCD and SPD with those who have OCD alone, showed that patients with OCD-SPD disorder had poorer insight, more negative symptoms, lower functioning, and more first-degree relatives with schizophrenia-spectrum disorders.26 In addition, significantly more patients in the schizotypal-related OCD group (11 [73%] of 15) than in the non-SPD group (8 [23%] of 31) were treated with an antipsychotic-SSRI combination; treating clinicians judged that more patients in the OCD-SPD group required low-dose antipsychotic augmentation (risperidone, 0.5 to 1.5 mg/d; olanzapine, 5 to 10 mg/d; haloperidol(Drug information on haloperidol), 2.5 mg/d) to obtain a satisfactory treatment response.
Our clinical experience indicates that a substantial proportion of patients with OCD may receive a misdiagnosis of schizophrenia and be continuously treated with higher doses of antipsychotic agents with or without SRIs. This treatment strategy may increase the risk of EPS and tardive dyskinesia, to which patients with OCD-SPD seem to be particularly vulnerable.26 Dosage regimen, duration of treatment, efficacy, and tolerability of antipsychotic augmentation to SRIs in patients with comorbid OCD and SPD merit further investigation.