However, this questionnaire is more likely used in research than in clinical practice. In terms of diagnosing a non-bizarre delusion as a delusion, ample support should be provided through fact checking. In case of non-bizarre delusions,  Psych Central notes, "All of these situations could be true or possible, but the person suffering from this disorder knows them not to be (e.g., through fact-checking, third-person confirmation, etc.)." Treatment
A challenge in the treatment of delusional disorders is that most patients have limited insight, and do not acknowledge that there is a problem. Most patients are treated as out-patients, although hospitalization may be required in some cases if there is a risk of harm to self or others. Individual psychotherapy is recommended rather than group psychotherapy, as patients are often quite suspicious and sensitive. Antipsychotics are not well tested in delusional disorder, but they do not seem to work very well, and often have no effect on the core delusional belief. Antipsychotics may be more useful in managing agitation that can accompany delusional disorder. Until further evidence is found, it seems reasonable to offer treatments which have efficacy in other psychotic disorders.Psychotherapy for patients with delusional disorder can include cognitive therapy which is conducted with the use of empathy. During the process, the therapist can ask hypothetical questions in a form of therapeutic Socratic questioning. This therapy has been mostly studied in patients with the persecutory type.
An attempt to contradict the belief is likely to arouse an inappropriately strong emotional reaction, often with irritability and hostility. They will not accept any other opinions. The belief is, at the least, unlikely, and out of keeping with the individuals social, cultural, and religious background. The person is emotionally over-invested in the idea and it overwhelms other elements of his or her psyche. The delusion, if acted out, often leads to behaviors which are abnormal, and out of character, although perhaps understandable in light of the delusional beliefs. Other people who know the individual observe that the belief and behavior are uncharacteristic and alien.Additional features of delusional disorder include the following:
It is a primary disorder. It is a stable disorder characterized by the presence of delusions to which the patient clings with extraordinary tenacity. The illness is chronic and frequently lifelong. The delusions are logically constructed and internally consistent. The delusions do not interfere with general logical reasoning (although within the delusional system the logic is perverted) and there is usually no general disturbance of behavior. If disturbed behavior does occur, it is directly related to the delusional beliefs. The individual experiences a heightened sense of self-reference. Events which, to others, are nonsignificant are of enormous significance to him or her, and the atmosphere surrounding the delusions is highly charged.However this should not be confused with gaslighting, where a person denies the truth, and causes the one being gaslit to think that they are being delusional.