1. Introduction
Obsessive-Compulsive Disorder (OCD) manifests in a variety of symptoms, including intrusive thoughts, compulsive habits, and mental acts. Obsessive and compulsive behaviors can cause severe discomfort for the patient and disrupt the normal process of life, work performance, routine social activity, or personal relationships. Medication and cognitive-behavioral therapies are used to treat this disorder, which can dramatically improve 20%-30% of these disorders [1]. One of the methods that may promote the treatment of this disorder is Attentional Bias Modification (ABM) [2, 3]. In this study, we aimed to evaluate and compare the effectiveness of ABM and Selective Serotonin Reuptake Inhibitors (SSRIs) in reducing the symptoms of OCD.
2. Materials and Methods
This is a clinical trial with a pre-test-post-test design conducted on 80 patients with OCD (diagnosed by a psychiatrist) referred to Amirkabir Hospital in Arak City, Iran. The severity of their OCD was assessed by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Then, they were randomly divided into two groups of 40 people; the first group received standard drug therapy with specific SSRIs (according to the drug reference books), and the second group received ABM treatment in 10 sessions, one session per week each for 30 min. At the end of intervention, the two groups were compared in terms of the efficacy of two treatment methods based on the dependent variables.
For ABM treatment, the researcher first prepared images displaying the common obsessive-compulsive patterns and then evaluated their validity and reliability. Then, for each pattern, 30 images with the highest scores were selected to correct the attentional bias of participants. They completed the Y-BOCS and dot-probe paradigm test after the intervention. The collected data were analyzed in SPSS V. 23 at a significance level of 0.05.
3. Results
Table 1 presents the prevalence of obsessive-compulsive symptoms in the two groups of drug therapy and ABM. As can be seen, obsession with pollution was the most prevalent symptom in two groups. Table 2 compares the severity of obsessive-compulsive symptoms in the two groups before and after the intervention. The independent t-test results showed no significant difference between the two groups in the mean severity of obsessive-compulsive symptoms (P>0.05). Statistical analysis showed that drug therapy significantly reduced symptoms of OCD compared to the ABM method (P=0.007).

4. Discussion
Overall, the results of this study showed that ABM treatment could not significantly affect OCD compared to drug therapy. Drug therapy was able to reduce the symptoms of OCD more than ABM. The ABM could significantly reduce the attentional bias of patients, while drug therapy could not reduce it in patients. Attentional bias can be the result of an initial risk or threat assessment that, in turn, can trigger harmful cognitive, physiological, and behavioral responses, even though the risk is mild or obscure. Research shows that anxious people pay more attention to threatening information, and these changes have been shown in the amygdala of the brain [6].
In this study, the reduction in attentional bias was significant in the ABM group (P=0.045), but the decrease in the severity of OCD symptoms was not significant in this group (P=0.228). In explaining this result, we can indicate the results of Malgrow’s study. He showed that the information that a person would consider depends on their relative importance of the information he assumes in relation to his/her self-concept. If one can separate individual attention from threatening stimuli and move toward neutral stimuli by using cognitive psychology findings and learning principles, the bias of one’s attention may reduce.
The reduction in attentional bias was not significant in the drug therapy group (P=0.328), but the decrease in the severity of OCD symptoms was significant in this group (P<0.001). Symptoms of OCD have a biological basis and may have important psychological implications for the patient. In some studies, the association between serotonin gene alleles and attentional bias has also been stated as a factor for the incidence of OCD [15]. Thus, given the relation of drug therapy with using SSRIs, it may reduce attentional bias. On the whole, the ABM method does not have a significant effect on decreasing symptoms of OCD in the short term but reduces attention bias in patients with OCD.
Ethical Considerations
Compliance with ethical guidelines
This research is a registered clinical trial. It was approved by the  Research Ethics Committee of Arak University of Medical Sciences (Code: IR.ARAKMU.REC.1396.284).
Funding
The present paper was extracted from the PhD. thesis of the first author, Khadijeh Mohsenpourian, Department of Psychiatry, School of Medicine, Arak University of Medical Sciences. The study received financial support from the Deputy of Research and Technology of Arak University of Medical Sciences
Authors' contributions
Conceptualization and methodology by Khadijeh Mohsenpourian, Mostafa Nokani, and Hamidreza Jamilian; validation, analysis and investigation by Khadijeh Mohsenpourian and Mostafa Nokani; resources and initial draft preparation by Khadijeh Mohsenpourian, Mostafa Nokani, and Mohsen Ghasemi; editing and final draft preparation by all authors; visualization, supervision, and project administration by Khadijeh Mohsenpourian and Mostafa Nokani.
Conflicts of interest
The authors declare no conflict of interest.
Acknowledgements
The authors would like to thank the Deputy for Research and Technology of Arak University of Medical Sciences for financial and spiritual support and the Psychiatry Clinic of Amirkabir Hospital for their cooperation.

References