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 them, 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. Causes The cause of delusional disorder is unknown, but genetic, biochemical, and environmental factors may play a significant role in its development. Some people with delusional disorders may have an imbalance in neurotransmitters, the chemicals that send and receive messages to the brain. There does seem to be some familial component, and immigration (generally for persecutory reasons), drug abuse, excessive stress, being married, being employed, low socioeconomic status, celibacy among men, and widowhood among women may also be risk factors. Delusional disorder is currently thought to be on the same spectrum or dimension as schizophrenia, but people with delusional disorder, in general, may have less symptomatology and functional disability. Diagnosis 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 delusional disorder, 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