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Psychiatric-Mental Health Nursing

15.3 Delusional Disorder

Psychiatric-Mental Health Nursing15.3 Delusional Disorder

Learning Objectives

By the end of this section, you will be able to:

  • Define and understand the diagnosis of delusional disorder
  • Outline the common types of delusions experienced in delusional disorder
  • Recall the treatment approaches used in delusional disorder

Although there are some similarities, delusional disorder differs from schizophrenia because diagnosis only requires the presence of delusions and none of the other earmarks of psychosis. Those with delusional disorder may not be impaired like those with other psychoses. This section will focus on delusional disorder, the different types, treatments, and complications.

Defining and Diagnosing Delusional Disorder

Delusions are fixed false beliefs based on inaccurate judgment of an external reality. Delusional disorder is characterized by clients having one or more non-bizarre delusions that have lasted for one month or more. These clients do not appear functionally impaired other than by the ramifications of the delusion(s). Those with delusional disorders often present with other mental health disorders, most commonly depression and anxiety. The delusions cannot result from a medical or known substance or medication. In other words, delusional symptoms caused by medical illnesses or diseases do not constitute delusional disorders.

Diagnosing delusional disorder can be complex. These clients usually function well when focused on something other than the delusion. When focused on the delusion, however, they will spend significant and sometimes inordinate amounts of time attempting to accrue evidence or align others with their beliefs. Individuals suffering from this disorder may contact health-care professionals, attorneys, private detectives, the police, and even the court system to confirm their beliefs. They do not have insight into their delusion. Attempts to dissuade them from their delusion will likely result in a negative response by the client, including hostility and aggression. The best way to determine the presence of the disorder is to assess the validity of their claim. Rule out any medical cause and differentiate the delusional disorder from another mental health disorder. For instance, suppose a client claims to have bugs in their urine (delusional parasitosis). The diagnostic assessment entails obtaining copies of the client’s medical records, collecting collateral information from family members, physical examination and labs, ascertaining if the client has taken any other medications or substances, and communicating with the providers they have seen over the past several years (Healthline, 2024a).

Prevalence, Risk, Causes, and Course of Delusional Disorder

The risk of delusional disorder is small, 0.05 to 0.1 percent in population-based studies. Risk factors include family members with schizotypal personality disorder and schizophrenia (Jadhav et al., 2014). The age of onset is between thirty-five and forty-five years but can range between eighteen and eighty years. The cause of delusional disorders is unknown. There is evidence that dysfunction in dopamine neurotransmitter functioning may play a role, along with medial/frontal and anterior cingulate cortex brain abnormalities. The disorder can emerge suddenly or gradually. For example, an acute onset might happen as a part of a stressful event. The course of the illness is relatively stable and chronic. When considering this diagnosis, consider normative cultural beliefs; Western cultures may misdiagnose some traditional and faith-based beliefs as delusional behavior.

Cultural Context


Stress is expressed differently from the lens of varying cultural frames. To ensure that these concepts of distress are conceptualized from these perspectives, it is essential to frame these experiences as the client experiences them. A Shona concept is kunfungisisa or “thinking too much,” and can be a precursor to anxiety, depression, and somatic complaints (“My heart hurts”). This is prominent in the Shurugi district in Zimbabwe. It is a perseverative process focusing on bodily symptoms, including aches, lack of appetite, and sleeplessness. The symptoms can also include anxiety, depression, panic, anger, hallucinations, suicidal thoughts, and substance misuse. Recognition of the concept is imperative. It is a sign of stress and anxiety, not a somatic delusion. Nursing interventions focus on the recognition of the cultural concept of distress and the implementation of culturally appropriate care, such as faith-based spiritual and community support and potential medication management for anxiety and or depression.

(Patel et al., 1995)

Those who suffer from delusional disorder have good outcomes when treated. If not treated, several adverse outcomes can result from behaviors related to the delusions.

Social Isolation

Paranoia can make someone feel alone; other people do not understand or may feel threatened by the person with the delusions. Interactions with other individuals may cause their delusions or moods to worsen. They may become irritable, threatening, or volatile. In such cases, social isolation might result from others staying away or the individuals protecting themselves from others. Social isolation might serve to maintain or further aggravate the delusions.

Depression and Self-Harm

Social isolation and mistrust can lead to mood symptoms, such as depression, creating a cycle. The symptoms of depression—no energy, no motivation, anhedonia, guilt, sad mood, irritability, problems sleeping, and suicidal thoughts—can worsen this social isolation by increasing the need to stay at home. Additionally, those suffering from certain delusions can engage in self-harming behaviors. For instance, a client with delusional parasitosis or a belief that their body is infested may scratch themselves repeatedly to rid themselves of the infestation. Assessment of those with those beliefs for self-harming behaviors is essential in ensuring their health and well-being.


The intersectionality between mental health and the legal system is involved when commitment is a concern (danger to self, others, or gravely disabled), when there is a question regarding the capacity to participate in their defense during criminal cases, and if there was diminished capacity when committing a crime. In general, those suffering from mental illness are overrepresented in the criminal justice system. Substance Abuse and Mental Health Services Administration (SAMHSA, 2022) estimates 18 percent of the general population have a mental illness, though 37 to 44 percent of incarcerated individuals have a mental illness.

Those suffering from erotomaniac, jealous, and persecutory delusions, for instance, can become involved in the legal system if they stalk their object of desire, cross boundaries, or attempt to harm others. The nursing role in forensic settings is to provide safety and security for the client while providing nonjudgmental care and maintaining appropriate boundaries (Dhaliwal & Hirst, 2016).

Common Types of Delusions

Delusional disorder usually involves non-bizarre delusions but can have bizarre content. The types of delusions and subtypes include erotomaniac, grandiose, jealous, persecutory, and somatic.


Erotomaniac delusions involve thoughts of an idealized love between the client and another individual. They usually involve a celebrity or someone who they have never met before. The person affected by the delusion might attempt to connect with or communicate with the celebrity. The belief usually starts with an initial encounter and develops over time as the feelings grow, and the delusion becomes set. These beliefs might lead to stalking or assaultive behaviors, resulting in involvement with the legal system. Celebrities with delusional stalkers include Rihanna, Madonna, Selena Gomez, and Taylor Swift. The stalking behaviors resulted in arrests, probations, home relocations by the celebrities, and restraining orders. The individuals affected by these delusions are often vulnerable, isolated, sexually repressed, and have poor social skills (Seeman, 2016).


Grandiose delusions involve the idea that the individual has done something great or is someone extraordinary. These beliefs might include that they have great wealth, they have power or influence, they are a world-renowned scientist or novelist, or they are greatly admired. This differs from the grandiosity of mania because the mood symptoms affiliated with mania are not present with the delusion. Clients with delusional disorder, grandiose type, are rare and may present as a comorbidity with a psychotic or mood process (Healthline, 2024a).


Jealous delusions are when the individual believes their partner or spouse is cheating on them or will cheat despite evidence to the contrary. Delusionary beliefs of the jealous type can lead to dangerous behaviors, including harm to the partner.


Persecutory or paranoid delusions involve the central theme that people are out to get them. They are the most prevalent of the delusional disorder subtypes. Those suffering from persecutory delusions believe they are being watched, harassed, or obstructed. Anxiety and worry have a significant role in the mechanism of these types of delusions (Startup et al., 2016) and can be a target for psychological intervention. These individuals may also present themselves as irritable or aggressive, guarded, suspicious, or isolative. These individuals may believe that others are trying to hurt them, poison them, spy on them, or acting against them. They often socially isolate, live away from others, and do not interact with others. Additionally, they may involve the legal system to get justice for the wrongs they believe have been done to them.


Somatic or “of the body” delusions involve health, bodily symptoms, or undiagnosed disease. Onset is either acute or gradual, unremitting; these clients usually do not receive mental health care. When they do, they typically present first in infectious disease, medical, or dental clinics and are referred to mental health as a consultant. Delusional parasitosis is a type of somatic delusion where the individual believes they are infected with insects or parasites, for instance. Those with delusional parasitosis often present with comorbid psychiatric illnesses, such as depression, substance misuse, and anxiety. The clients will usually claim that they have extensive knowledge of their infestation and that their family members have been exposed or affected; they may bring a sample of their infestation and may experience formication, a hallucination that bugs are crawling on the skin (Campbell et al., 2019).

Real RN Stories

Nurse: Pam, advanced practice psychiatric nurse
Years in Practice: Twelve
Clinical Setting: Outpatient mental health facility
Geographic Location: Community, rural

I was an advanced practice psychiatric nurse and received a referral from an infectious disease clinic. The client arrived with a cup of urine in their hands. The client stated, “I have a leishmaniasis infection. Look at my urine.” The client had traveled to Australia and came home with symptoms of urinary frequency and burning. They had a friend who traveled to Central America and came home to find that they had the infection; the friend received significant treatment afterward. The client was convinced that they now had the same infection. After receiving word from the infectious disease clinic that leishmaniasis is not endemic to Australia and that the client had a simple urinary tract infection remedied by antibiotics, the client was not convinced. They went to another infectious disease clinic and were told the same thing. The client has been to several providers and clinics, insisting they suffered from the infection. The client was now being evaluated by me today as a referral from the last infectious disease clinic.

I first spent time developing trust and therapeutic alliance with the client. I did not challenge the delusions and encouraged the client to engage in medication therapy after a few sessions. The client was initiated on a second-generation antipsychotic and a serotonin reuptake inhibitor for their comorbid anxiety disorder (OCD). After eight weeks on the medication, the client reported to me that they no longer needed “to see someone for their leishmaniasis. I am cured.”

Treatment of Delusional Disorder

The initial step to treating delusional disorder is establishing therapeutic rapport and trust. These clients need to feel validated and engaged in their treatment through empathy and understanding. It is crucial to align treatment decisions with the client, including their support system, to facilitate adherence to treatment. Medical and psychosocial interventions follow the establishment of the trusting therapeutic relationship.


Clients with delusional disorder often do not have insight into their illness. It is not easy to come to agreement on first-line treatments when the client disagrees that they have a psychotic disorder. The first step is to give the client space and time to consider the diagnosis; sit with it, take time to understand it, and allow themselves to become comfortable with it. Educating the client when they are calm and open to information is the best approach to medication adherence and optimal outcomes. Overall, second-generation antipsychotics are the first choice in medications used to treat delusional disorders. Risperidone (Risperdal) is the medication most frequently cited in case studies with olanzapine (Zyprexa) and quetiapine (Seroquel) as second and third choices. Other medications used in delusional disorders are SSRIs and SNRIs in combination with second-generation antipsychotics. This combination assists with depression and anxiety, often seen in those with delusional disorder. For those clients who struggle with nonadherence to medication, long-acting injectables (LAI) have also been useful (Jalali Roudsari et al., 2015).

Psychosocial Approaches to Treatment

If the client is not willing or does not have the insight into their illness to take medications, adjunctive psychotherapy is the other option. The best outcomes for individuals with delusional disorder have been with cognitive behavioral therapy aimed at identifying the evidence, challenging the delusions, and targeting comorbid anxiety and depression. A clinical example of cognitive therapy for delusional disorder is the Thinking Well Intervention. This therapy involves having the client slow down their thinking, look for more evidence, generate alternative explanations and thoughts rather than delusions, find other ways to think about more logical and less distressing things, and then consider how their thinking affects their mood. This type of intervention has been effective in generating positive outcomes for distress in those with paranoid delusions (Waller et al., 2015). Supportive psychotherapy helps clients work through their experiences with the disorder, provides a framework for coping skills, and eases emotional distress.


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