Delusional disorder is a rare type of psychotic mental illness that is characterized by persistent delusions. Unlike more common psychoses, like schizophrenia, most people with this condition have non-bizarre delusions that cause little impairment in their lives. Resistance to accept that delusions are false beliefs means many people with delusional disorder refuse treatment. With therapy and antipsychotic medications, delusions may diminish. The prognosis depends on an individual’s willingness to get help, but because functioning is typically high, not getting treatment does not mean a person can’t live a normal life.
What Is Delusional Disorder?
Delusional disorder is a mental illness that causes a person to have delusions, or beliefs that are not true or that are highly exaggerated. The false beliefs occur when an individual misinterprets reality or perceives reality incorrectly. The kinds of delusions this disorder causes are most often not bizarre or fantastical; they are things that really could happen, such as being followed or being lied to by a friend.
Delusions are considered a symptom of psychosis, but delusional disorder usually causes less impairment than other psychotic conditions, like schizophrenia. Most people with delusional disorder function normally in their lives and do not appear odd or eccentric to others. They tend to keep quiet about their delusions. The condition may cause impairment in some cases—for instance, if a person is convinced someone is trying to kill them, they may not leave home and may not be able to work. Delusional disorder can be treated with therapy and medications, but resistance to treatment makes it difficult.
Types of Delusional Disorder
Delusional disorder can be classified as one of several types based on the types of delusions or false beliefs a person has:
- Erotomanic. With this type of delusional disorder the individual believes someone is in love with them, often someone famous or newsworthy. The delusions may lead to stalking behaviors and trouble with the law as a result.
- Grandiose. Grandiose delusions give an individual an inflated sense of self-worth or of abilities and talents.
- Jealous. Jealous delusions focus on a person’s partner and a perceived disloyalty or cheating behaviors.
- Nihilistic. A nihilistic delusion is related to a sense or belief that something really terrible is going to happen.
- Persecutory. Persecutory delusions are those related to being harmed by others. A person with persecutory delusional disorder may think someone is out to get them, is lying to them, or is spying on them. This type can lead to unnecessary calls to law enforcement.
- Referential. These are delusions that actions, statements, and situations are directed at oneself, when they really are unrelated.
- Somatic. Someone with somatic delusions believes that he or she is sick, has a disease, or has some physical disability or defect.
- Mixed. When someone experiences more than one type of false belief it is classified as mixed delusional disorder.
Facts and Statistics
Delusional disorder has not been extensively studied, and much of the information experts have about it are based on case studies, not rigorous research with multiple patients.
- Delusional disorder is considered to be rare as a mental illness, and delusions are most often a sign of another condition that is more common, like schizophrenia.
- This mental illness is most likely to begin in middle age or later.
- One study found that delusional disorder may be present in prison populations at eight times the rate of the general population.
- Studies have also found that, although people with delusional disorder function better than those with schizophrenia, their delusions are more firmly held and more severe.
Symptoms and Diagnosis of Delusional Disorder
It can be difficult to diagnose delusional disorder for a couple of reasons. One of these is that people with the condition often don’t talk about their false beliefs and often function normally as a result. Another reason is that these individuals do not realize their beliefs are false and do not see anything wrong with how they think. This can lead to resistance to being evaluated for any mental illnesses.
If a person can be convinced to be evaluated, there are issues with distinguishing between delusional disorder and other mental illnesses with psychotic symptoms. First, in a diagnostic evaluation the mental health professional must determine if the person is truly having delusions or if their beliefs are true. It can help to talk to family or friends to make this determination. Observations of the patient and interviews also help the professional decide if delusions are present.
When a person is determined to be delusional it is then necessary to rule out other conditions. A physical examination helps rule out medical conditions, but a mental health professional should also consider and screen for other psychotic conditions like schizophrenia or manic phases of bipolar disorder. To screen for delusional disorder a mental health expert follows the symptoms and criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders:
- Delusions have been persistent for at least a month.
- The patient does not meet the criteria for schizophrenia.
- If there are hallucinations they are minor and related to the delusion.
- Behaviors are not bizarre and the patient functions mostly normally.
- Any periods of depression or mania are brief.
- The delusions cannot be better explained as being caused by another mental illness, a physical illness, or a medication or substance abuse.
The main symptom of delusional disorder is having one or more delusions, but there may be other signs. These include irritability, depression, anger, obsessive thoughts, and minor hallucinations directly related to the delusions.
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Causes and Risk Factors
The exact cause or causes of delusional disorder are not known. As with other mental illnesses, it is likely that there are multiple complex causes, but determining what causes the condition is also challenging because it is not well studied. Genetics probably play a role in delusional disorder. There is evidence that people who have family members with the condition or with other psychotic conditions, like schizophrenia, are at a greater risk for developing it.
There may also be biological contributing factors. Abnormalities in brain structures or imbalances in the chemicals used for signaling in the brain may be related to the development of delusions and delusional disorder. Environmental factors may also play a role. These may include stress, substance abuse, and social isolation. Some risk factors that have been determined to put someone at a greater risk for having delusional disorder include being an immigrant and having poor vision or hearing loss, although why these may be related to delusions is unknown.
As with many mental illnesses, delusional disorder often occurs with other mental illnesses or substance use disorders. Co-occurrence may be explained by the fact that many of these conditions have the same or similar risk factors. Or, it may be that one condition puts a person at risk for another. For instance, misusing drugs or alcohol may trigger delusions in someone who was already predisposed to experience them. Also, struggling with some of the issues of having delusions could lead someone to use drugs or alcohol to cope. Although studies are limited, it has been found that depression is among the most common co-occurring mental illnesses with delusional disorder.
Treatment and Prognosis of Delusional Disorder
Treating delusional disorder is tricky because most people living with this condition resist treatment or start but don’t stick with it. Also, because most people function well with delusional disorder, there may be no push to be evaluated or treated. Treatment can help, though, if a patient is willing, and can reduce the severity of delusions.
Treatment for delusional disorder usually involves the use of antipsychotic medications and regular therapy. Medications most commonly used for delusional disorder are risperidone and olanzapine. Psychotherapy can help an individual learn to recognize the beliefs that are false. Behavioral therapies help a patient set goals and take positive actions to change their false thought patterns and resulting negative behaviors. Family therapy can help family members learn more about the condition and how to support their loved one.
The prognosis for delusional disorder varies depending on an individual’s willingness to recognize delusions and get treatment. This is a chronic illness that tends to persist, but most people don’t experience serious disruptions because of it. Treatment helps reduce symptoms, but even without treatment many people live healthy, productive lives.