Delusions are beliefs that are false, illogical and fixed. The deluded person is convinced that his delusion is real, and he cannot be persuaded otherwise. Although the term "deluded" is often tossed around by healthy people in the heat of an argument, delusions in the medical sense have a different quality. Everyone other than the patient would agree his delusion is not true, and it can't be explained by the person's world view, religious beliefs or social environment.
Neurological and Medical Causes
The first appearance of delusions, whether accompanied by other symptoms or not, should always raise the suspicion of an underlying neurological problem. As explained in "Adams and Victor's Principles of Neurology," many different disorders of the brain can lead to delusions. Delirium is a transient state, common in elderly people who are hospitalized for any reason, consisting of confusion, hallucinations and delusions. Dementia often cause delusions, especially Lewy Body Dementia, as a review in "Age and Ageing" explains. Huntington's chorea is a degenerative disease of the brain whose symptoms include uncontrollable movements and delusions. Strokes and tumors can cause delusions. Seizures disorders can be accompanied by delusions, especially partial complex seizures, in which the patient is in an altered state of consciousness. Diffuse processes affecting the brain, such as infections, multiple sclerosis, B12 deficiency and an excess of cortisol, can all lead to delusions. Hallucinogens, such as LSD and PCP, and poisoning with heavy metals are other causes of delusions.
Delusional Disorder
Delusional disorder, as defined by the "Diagnostic and Statistical Manual of Mental Disorders," involves nonbizarre delusions, meaning situations that could theoretically occur in reality. In a patient with delusional disorder,no other significant symptoms exist, and other than having this one irrational belief, the person behaves and functions normally. Delusions seen in this disorder can be erotomanic, which means that a patient believes that an important person is in love with him. Other types of delusions include persecutory delusions and somatic ones, meaning that the patient is convinced that he has a medical illness and no amount of proof to the contrary will reassure him.
Schizophrenia
Schizophrenia is a chronic mental illness, symptoms of which include thought disorder, hallucinations and delusions. Delusions in schizophrenia are often bizarre, which means they could not possibly occur in reality. For example, the patient might believe he's been abducted by aliens. He might believe he can read minds or that other people can take thoughts out of his head. The patient with paranoid delusions believes he is being followed and persecuted. Paranoid delusions can lead the patent to protect himself by attacking those he believes are persecuting him.
Other Psychotic Disorders
Delusions are part of the symptoms of brief psychotic disorders, which can occur one time in a person life, never to return. Sometimes they are precipitated by an acute stressor, such as an inability to sleep for several days. Both depression and mania can be accompanied by delusions. As explained in "Kaplan and Sadock's Comprehensive Textbook of Psychiatry," the content of delusions in mood disorders is usually congruent with the type of mood disturbance. Patients with psychotic depression may feel that they are responsible for the destruction of the world. A manic patient, on the other hand, might think that she has special powers and can fly.
References
- "Adams and Victor's Principles of Neurology"; Maurice Victor and Allan Ropper; 2001
- "Age and Ageing"; Review: Delusions in Dementia; Richard Harvey; 1996:25:405-408
- "Kaplan and Sadock's Comprehensive Textbook of Psychiatry"; Virginia Sadock and Pedro Ruiz (eds.); 2009
- "Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR Fourth Edition"; American Psychiatric Association; 200
