Some individuals with OCD exhibit obsessive thinking that is also characterized by delusions. Five percent of OCD patients are convinced that their obsessive-compulsive thoughts are real, and another 20% believe them, but not to the point of conviction. Therefore, the lack of “self-knowledge” must be considered as a criterion to diagnose patients who are convinced of their own thinking. The difference between delusional disorder and obsessive-compulsive disorder is that obsessive-compulsive disorder involves compulsive actions. Because in OCD, obsessive-compulsive thinking is often accompanied by obsessive-compulsive actions. Obsessive-compulsive thinking and depressive rumination It is difficult to make a clear distinction between obsessive-compulsive thinking and depressive rumination. The difference between the two lies in the content of the thinking and the degree of resistance to it. Unlike obsessive-compulsive thinking, the content of depressive rumination is pessimistic and ends in contemplation. Also, people with depressive rumination are less likely to make an effort to suppress these thoughts, whereas people with OCD make an effort to suppress them. When a patient suffers from both OCD and depression is, he will exhibit both symptoms, but only the obsessive-compulsive symptoms are dealt with in the exposure association. In clinical practice, we also find that patients suffering from depression believe that treatment is ineffective. Such a view affects the patient’s positive evaluation of treatment progress and affects the patient’s motivation, although it is not related to OCD, but it needs to be addressed in the treatment. Temporal lobe epilepsy: Occasionally, obsessive-compulsive ideas and behaviors may appear in the form of seizures and other symptoms of temporal lobe epilepsy, and tests such as EEG and EEG topography can help identify them. Generalized anxiety disorder: generalized anxiety has many similarities to OCD in terms of excessive worrying, but, unlike the content of obsessive-compulsive thinking, with excessive worrying, the specific content of the worry is generally present in real life and the patient does not agree that their worries are inappropriate (self-coordinated ego syntonic) and they do not feel that they should not worry about those things. In contrast, the content of obsessive-compulsive thoughts is generally fictitious and they are considered inappropriate for these thoughts, and they do not feel that they should not occur. In addition, both patients with generalized anxiety disorder and patients with OCD worry about everyday things, such as worrying that their child will get sick, and patients with generalized anxiety disorder worry about the long-term consequences of illness (e.g., academic regression, physical weakness, etc.), whereas patients with OCD pay attention to the germs of illness (e.g., their child’s cold and flu virus will grow in large numbers). For those patients who do not have compulsive actions, but only compulsive thinking, it is especially important to distinguish between apprehension and compulsive thinking. Phobias: Specific phobias and obsessive-compulsive disorders are very similar if ritual behaviors are not taken into account. For example, patients with germs and rats are often able to reduce their anxiety by successfully avoiding rats, but a patient with OCD who has the obsessive-compulsive thought of the “rat virus” will still feel infected with germs even after knowing that a rat appeared in a certain place only a few hours ago. The patient will feel infected even when he knows that a place was only a few hours ago. These problems usually lead the patient to subsequently adopt avoidant behaviors (e.g., heavy laundry. bathing, etc.). These behaviors do not usually occur in patients with specific phobias. Hypochondria and body dysmorphic disorder Hypochondria is characterized by a particular concern for one’s health, and body dysmorphic disorder is concerned with what deformities there are in one’s body, both of which are also elements of obsessive-compulsive thinking in OCD patients. The best way to distinguish OCD from them is in terms of both of these aspects of content. Most hypochondriacs and body dysmorphic disorders are concerned with only one aspect of the problem. Moreover, while OCD patients fear contracting a disease in the future, hypochondriasis and body dysmorphic disorder usually focus on something that is already present, such as the hypochondriac fear that they have already contracted something. To distinguish the stereotypical bodily behavior of these two psychological disorders from OCD, it is important to analyze the functional relationship between the behavior and obsessive thinking. The organic tics are usually automatic and their purpose is no longer related to suppressing the painful annoyance caused by obsessive thinking. It is relatively easy to distinguish behavioral tics from “pure” compulsive actions, and it is rare to find patients with OCD who have only pure compulsions. As we mentioned earlier, the probability of OCD being complicated by a tic disorder is high, so it is often possible for a patient to have both disorders. As with depressive rumination, it is important to distinguish between tics and compulsive actions for patients with both disorders, because the ritual behavior blocking method is aimed at compulsive actions, not tics.