Differential diagnosis includes ruling out other causes such as drug-induced conditions, dementia, infections, metabolic disorders, and endocrine disorders. Other psychiatric disorders must then be ruled out. In<unk> , mood symptoms tend to be brief or absent, and unlike schizophrenia, delusions are non-bizarre and hallucinations are minimal or absent. Interviews are important tools to obtain information about the patient's life situation and history to help make a diagnosis. Clinicians generally review earlier medical records to gather a full history. Clinicians also try to interview the patient's immediate family, as this can be helpful in determining the presence of delusions. The mental status examination is used to assess the patient's current mental condition. A psychological questionnaire used in the diagnosis of the<unk>  is the Peters Delusion Inventory (PDI) which focuses on identifying and understanding<unk>  thinking. 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.)."
Delusional disorder
Paranoid personality disorder
Externalizing disorder
Substance-induced psychosis
Internalizing disorder
Bipolar disorder
Dissociative disorder
Schizophrenia