The current study aimed to investigate the severity of OCD symptoms in different episodes of BD. Ninety patients with a primary diagnosis of BD were divided into three groups (i.e., manic, depressive, and remission). Then the severity of OCD symptoms was assessed and compared. As our hypothesis, patients in the depressive group had higher OC symptoms scores, compared to the manic and remission groups. The findings of this study indicated that the mood state affects the severity of OC symptoms. Also, BD patients on remission had the lowest severity of OC symptoms compared to the manic and depressive groups.
Although the comorbidity rate of OCD and BD disorders is significant concerning the epidemiology and clinical contexts (
23,
24), some studies reported that in a manic episode, the appearance of OCD symptoms is very rare, but that relapse after remission of manic episode or at the onset of a depression episode (
9,
10). The results of this study are similar to the findings of Jeon et al., which showed that in two-thirds of 314 patients with the OCD-BD diagnose, OCD symptoms had the most severity in the depressive episode; Besides, they showed that in BD-OCD, BD was associated with earlier onset (
25). Karno et al. (
9) showed that in the manic episode, the severity of the OCD was lower. Takasu et al. (
26) also mentioned that the symptoms of patients with a primary diagnosis of OCD were improved during a manic episode and remission, but the severity of OCD symptoms was increased during the depression episode. In line with the findings of the current study, Ozdemiroglu et al. (
14) also found the depression was correlated with active OC symptoms in BD patients. Furthermore, the majority of BD-OCD patients stated that their previous OC symptoms appeared predominantly during the depressive episodes. Mahasuar et al. (
27) also showed worsening of OCD in depression episodes and improvement in the manic episode, which is similar to our findings and observations made previously. Besides, it supports the argument that comorbid BD affects the course of OCD in a distinct manner.
Previous studies on the comorbidity of these two disorders have shown that these patients have a higher chance of developing other disorders, including anxiety and substance abuse disorders (
4,
28,
29). According to the findings on the comorbidity of these two disorders, it leads BD to a chronic course, but BD affects the OCD in a distinct way, which causes a seasonality course of OCD. It is likely that both disorders may have common pathophysiology, or emotion dysregulation may be the common etiology of these two disorders (
30).
Regardless of the epidemiological associations, the comorbidity of these two disorders can be a dilemma, because serotonin reuptake inhibitors (SSRIs) that are commonly used to treat OCD increases the risk of manic episodes (
31-
33). A study on untreated BD patients using a PET scan showed that the neurotransmitter-serotonin binding potential in the insula and Dorso Cingular Cortex in BD-OCD patients is higher than those BD patients without OCD (
34). Another study has shown that patients with both BD and OCD are more likely to have a family history of mood disorders and a lower probability of having a family history of OCD (
35).
The manic episode might have contributed to the under-reporting of distressful OC symptoms, appearing in a lower comorbidity rate. In contrast, possible over-reporting of OC symptoms in patients with depression may have caused a mislabeling of ruminations as obsessions (
24). It seems that BD has a patio plastic modulating effect on the course of OCD. Higher severity of OCD in depression episodes and improvement in the manic episode also is consistent with the changes in the expression of OCD due to BD (
16,
36). Furthermore, some case reports described the onset of mania in response to treatment with SSRI in OCD patients, despite some of them had no history of BD (
37).
5.1. Limitations
The findings of this study showed the severity of the OCD is significantly higher in women, therefore, it is suggested to further investigate the possible reasons for this difference. Also, because of the limited number of bipolar patients with mixed features or in the hypomanic episode, they were excluded from the study, so we suggest to investigate these patients in future studies. Additionally, it is better to adjust the psychotic features of patients in future studies, it is also recommended to compare the severity of the OCD symptoms in depression episodes of bipolar patients and unipolar depressive disorder. In the current study, the number of episodes of patients was not considered despite the possible effect on OCD severity.