Delusional Disorder

What is delusional disorder?

Delusional disorder is a mental health condition listed in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). People with delusional disorder experience at least one delusion, lasting for at least a month. People who live with this mental health condition may have psychotic symptoms that appear similar to schizophrenia, but they do not meet the full diagnostic criteria for schizophrenia. When people with delusional disorder experience hallucinations, they must be related to the content of the delusions ^[1]. 

Types of delusional disorder 

Different types of delusional disorders can vary based on the content of a person’s delusions. These types are outlined below ^[2]:

• Erotomanic Type: People with this delusion believe that another person is in love with them. Typically, they think that someone famous or of high status has fallen in love with them. 
• Grandiose Type: Grandiose delusions surround the belief that a person has incredible talent, power, or knowledge or is associated with influential people, such as celebrities or deities. 
• Jealous Type: A person with jealous delusions believes that their significant other is being unfaithful. 
• Persecutory: Persecutory delusions lead a person to believe that someone is conspiring against them, attacking them, or somehow stopping them from achieving their goals.
• Somatic Type: Somatic delusions are related to bodily sensations. People with somatic delusions may feel that their bodily functions or sensations are abnormal. 
• Mixed Type: When a person has mixed delusions, they experience at least two types of delusions. For instance, they may have both somatic and grandiose delusions. 

Symptoms of delusional disorder

People with delusional disorder have one or more irrational beliefs, called delusions. In most cases, people with delusional disorders function well, and their behavior does not appear bizarre ^[2].

Some specific symptoms of delusional disorder are as follows ^[2]:

• Having a false belief that remains, even when a person is presented with evidence that the belief is not true
• Remaining fixed on a belief that most other people know is false 
• Maintaining at least one delusional thought for a month or more 
• Social isolation resulting from delusional thinking

Diagnosing delusional disorder

A mental health provider, like a psychiatrist, can diagnose delusional disorder. To diagnose this condition, a mental health professional will look for the following criteria, which are contained in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM 5) ^[2]:

• The presence of at least one delusional thought, lasting for at least one month
• No evidence of a physiological, medical, or substance-related cause of the delusions
• No proof that another mental health disorder explains the delusional thinking
• Delusions that are non-bizarre, meaning that while they are false, they are situations that could happen in real life

In addition to performing a psychiatric evaluation to diagnose delusional disorder, a professional may conduct additional testing, such as a urine drug test, to rule out substance-induced delusions. Medical professionals may also consult friends and family members about the timeline of the delusions and any other symptoms a person has to rule out alternative psychiatric diagnoses. In addition, since other mental health conditions can appear similar to delusional disorders, a mental health professional often has to evaluate the criteria of other mental health conditions, like schizophrenia or schizoaffective disorder, to rule out alternative diagnoses ^[2]. 

Conditions related to delusional disorder

When a clinician diagnoses delusional disorder, they will rule out related psychiatric conditions to ensure that they have made an accurate diagnosis. Some other conditions that may look similar to delusional disorder are as follows:

• Schizophrenia: Individuals with schizophrenia experience at least two symptoms: delusions, hallucinations, disorganized speech, catatonic behavior, or negative symptoms (lack of motivation, flat affect). They also have trouble in interpersonal relationships, at work, or caring for themselves. The difference between schizophrenia and delusional disorder is that a person with delusional disorder does not meet all the criteria for schizophrenia. They may experience hallucinations related to their delusions, but they do not have additional symptoms of schizophrenia, such as flat affect ^[1].
• Obsessive-compulsive disorder (OCD): OCD may look like delusional disorder because people who live with this condition experience repeated, unwanted thoughts that cause them significant distress. They try to suppress these unwanted thoughts through compulsive behaviors, such as hand-washing. Obsessive thoughts may appear similar to delusions ^[3]. 
• Bipolar Disorder: Sometimes, people experience delusions during mood episodes that occur with bipolar disorder. To be diagnosed with delusional disorder, delusions must last for longer than mood symptoms ^[2].
• Major Depressive Disorder: Mood symptoms that occur with major depression can also result in delusions ^[2]. For instance, a person who is depressed may have a delusional sense of guilt or feel as if they are worthless, with no evidence to support these beliefs ^[4]. 

Causes of delusional disorder

There is not one single cause of delusional disorder, and experts disagree on the leading causes of the condition because so little research has been conducted. However, some of the following risk factors may contribute to the development of delusional disorder, based on what is known about the condition:

• Biological Factors: Medical conditions and neurological problems could contribute to delusions in some people ^[2].
• Substance Use: Drug and alcohol misuse has been found to precede delusional disorder, especially in men ^[5]. 
• Other Mental Health Disorders: In men, paranoid personality disorders like schizoid and schizotypal personality disorder tend to develop before the onset of delusional disorder ^[5]. 
• Genetics: Experts believe genetics may contribute to the risk of developing delusional disorder, because studies have shown that a family history of schizophrenia increases the risk of delusional disorder. Genetic variations associated with schizophrenia may also be linked to delusions ^[6].

Prevention of delusional disorder

There are no known ways to prevent delusional disorder. Sometimes, a person may have a genetic risk factor that predisposing them to develop the condition. The best way to avoid severe impairment from delusional disorder is to seek early intervention as soon as symptoms appear. Then, with a diagnosis and professional treatment, people can learn to manage symptoms of delusional disorder.

Treatment for delusional disorder

Helping someone with delusional disorder

If your loved one has symptoms of delusional disorder, there are things you can do to be supportive. First, when approaching your loved one, remember to remain positive. Avoid blaming them for their problems or accusing them of being illogical. 

Attempting to talk your loved one out of their delusions is unlikely helpful. Instead, you can offer a listening ear, express that you understand their anxious thoughts, and encourage them to seek treatment. 

Frequently asked questions about delusional disorder

What is the outlook for people with delusional disorder?

Based on what is known about delusional disorder, many people with this condition do not have significant impairment. In fact, they tend to function well psychologically when not discussing their delusion ^[2].

Some people with delusional disorder may experience difficulties at work and social isolation. However, treatment can help. The prognosis with treatment is generally good, and nearly half of patients with delusional disorder will respond well to medication ^[2]. 

Are there any long-term complications to delusional disorder?

While people with delusional disorder generally function well, there can be complications if the condition is untreated. For instance, some patients may develop symptoms of depression because of the stress associated with delusions. Others may have legal problems, as they may harass or stalk a person who is the object of delusional thinking, ultimately leading to criminal charges. People with delusional disorder may also become socially isolated because delusional thinking can interfere with relationships. 

How common is delusional disorder?

Delusional disorder is rare, with estimates that just 0.02% of the population experiences this mental health condition. Compared to other conditions, such as schizophrenia and mood disorders, delusional disorder is uncommon. Prevalence rates of the condition may be underestimated, as not everyone with delusional disorder seeks treatment ^[2].