Delusional Disorder

“Delusions are distinguished from mistaken beliefs in that delusional beliefs remain unchanged in the face of clear, reasonable evidence to the contrary” ~ Dr. Carol Tamminga, M.D, Stanton Sharp Distinguished Chair in Psychiatry

What is Delusional Disorder?

Delusional disorder is a rare disorder that tends to present in middle to later life and is slightly more common in women. It is a type of serious mental illness, a “psychosis” in which someone has trouble recognizing reality and distinguishing what is real from what is imagined. A delusion is a false belief that stems from an incorrect and imbalanced perception of reality.  Delusions, like all psychotic symptoms, can occur as a symptom within a variety of psychiatric disorders. However, the term delusional disorder is only used when delusions are the most prominent symptom.[1]

Schizophrenia is perhaps the most widely-known psychotic disorder in which delusions are frequently presented. However, a key difference between delusional disorder and schizophrenia is that, in the case of delusional disorder, the delusions will present without the common symptoms of other psychoses, such as hallucinations, impaired social behavior, and disorganized speech. [2]

The delusions presented within delusional disorder fall into two main categories: bizarre and, more commonly, non-bizarre:

  • Non-bizarre: These are occurrences that align with reality as they are plausible and could easily occur. Non-bizarre delusions are likely to only be detectable by close family or friends and can make the clinical diagnosis of delusional disorder difficult. These occurrences could include unfounded beliefs that a partner is being unfaithful, misguidedly believing someone is in love with them, irrational conviction that one is being poisoned, or unwarranted feelings of being followed or watched. These delusions will often stem from an actual occurrence that has been exaggerated or misinterpreted.
  • Bizarre: These involve implausible situations such as believing that thoughts have been inserted into their head or that they are, or a family member is, being controlled by an outside force. [3]

Symptoms and Types of Delusional Disorder

The presence of non-bizarre delusions is the most common and obvious symptom of this disorder. Other potential symptoms include:[4]

  • A pervasive distrust or suspicion of others
  • An irritable, angry, or low mood
  • Feelings of exploitation
  • Preoccupation with others’ actions and intentions/loyalty
  • Tendency to misinterpret situations and read into things incorrectly
  • Persistent bearing of grudges
  • Hallucinations (seeing, hearing, or feeling things that are not there) that are related to the delusion

Those suffering with delusional disorder do not tend to exhibit odd, disruptive, or anti-social behaviors that are unrelated to their delusion type.

There are several recognized sub-types of Delusional Disorder:[5]

  • Erotomanic: Patients believe that another person, often someone who is important or famous, is in love with them. This belief can lead to stalking behaviors, as they will try to make contact or pursue a relationship with the person.
  • Grandiose: Patients with this delusion may believe they have a special ability or remarkable talent, have made an important discovery, or have a relationship with someone important, such as a celebrity or the Pope. It could also be more generalized, where the person has an exaggerated sense of worth, knowledge, or power.
  • Jealous: Patients with this delusion believe that their partner, spouse, or lover is unfaithful.  It may be supported by some evidence. However, it is either exaggerated, falsified, or misinterpreted.
  • Persecutory: People with this type of delusional disorder believe that they (or someone close to them) are being plotted against, threatened, or mistreated or that someone is spying on them or planning to harm them. The person will often make repeated accusations and complaints to legal authorities. They may also react aggressively as a result of their perceived need for self-defense or retaliation.
  • Somatic: The patient believes that they have an illness, medical issue, physical defect, or bodily dysfunction.
  • Mixed: These people have two or more types of delusion.


Causes of psychotic disorders are largely unknown. However, studies have shown correlations to various genetic, biological, environmental, or psychological factors.

  • Genetic. Studies have found that delusional disorder is more prevalent in those with a family history of psychotic disorders.
  • Biological. An imbalance in the brain’s neurotransmitters, which interfere with the transmission of messages, has been linked to the formation of delusional symptoms.
  • Environmental/psychological. Evidence suggests that delusional disorder can be triggered by stress and through addiction to drugs and alcohol. Those who are isolated due to sensory impairments, such as sight or hearing loss, also appear to be more vulnerable to this disorder. [6]


Since delusional disorder is rare, doctors will commonly first evaluate the possibility of another psychotic disorder such as schizophrenia, a mood disorder, or a medical or neurological problem. These disorders can be difficult to diagnose for a multitude of reasons. Often, the person does not believe they are deluded or in need of psychiatric assistance. This can lead to distrust and concealment of thoughts and feelings, making treatment more complicated. In older patients, delusional disorder may coexist with dementia. [7]

When making a clinical diagnosis, the patient’s full medical and family history will be obtained, and a medical examination will be undertaken to rule out any illnesses that could cause the delusional symptoms, such as Alzheimer’s disease, OCD, epilepsy, schizophrenia, and substance misuse.

An evaluation will be undertaken as to the individual threat of the patient’s delusion in case it could provoke dangerous behavior.

Treatment and Outlook

Treatment for this disorder can be challenging, especially if the delusion has been present for a long time. As it is common for patients not to accept that they are suffering with a disorder, they may refuse all treatment options. It is beneficial in these instances for the person to be supported by family and friends and for all who are affected to receive education, support, and reassurance.  It is also essential for the sufferer’s support system to frequently and compassionately help them differentiate between reality and delusion.

Treatment may take one or more of the following forms:[8]

  • Treatment establishes a positive and effective physician-patient relationship, with support to address the complications the delusions may cause for the patient.
  • Psychotherapy is the primary treatment, as it provides a safe environment for patients to explore their delusions while cultivating healthier and more functional behaviors.
  • Hospitalization if the delusions trigger dangerous behavior.
  • Antipsychotics can be helpful; however, not all delusions respond to medication.
  • Ongoing education of family and friends along with support resources and family therapy.

Living with Delusional Disorder

The outlook for a person suffering from delusional disorder depends largely on the individual, the type of delusion, and the person’s specific conditions.

People with delusional disorder can usually remain employed and continue to socialize aside from the direct source of their delusion. Of course, in some cases, the delusion may be too overwhelming and the preoccupation with their delusions may disrupt their lives by causing inter-personal conflicts and preventing them from functioning normally in day-to-day life and society. [9]

As the sufferer commonly does not believe that they have a mental disorder, the condition is frequently chronic and long term. However, patients who engage with treatment can find relief from their symptoms, enter stages of remission, and even completely recover. Without treatment, delusional disorder can be a life-long illness.


There is no known way to prevent someone from developing a delusional disorder. However, early diagnosis and management of symptoms through treatment can help decrease the stress and disruption that this disorder can cause the sufferer.

If you are concerned about any issues discussed in this blog, please contact Heather R. Hayes & Associates – call 800-335-0316 or email today.

[1] Publishing, Harvard. “Delusional Disorder – Harvard Health”. Harvard Health, 2019,

[2] Tamminga, Carol. “Delusional Disorder – Psychiatric Disorders – MSD Manual Professional Edition”. MSD Manual Professional Edition, 2020,

[3] Publishing, Harvard. “Delusional Disorder – Harvard Health”. Harvard Health, 2019,

[4] Ba, and Quarantine Explained Social Distancing. “Delusional Disorder”. Webmd, 2021,

[5] Hollander, E. et al. “Body Image In Mood And Psychotic Disorders”. Encyclopedia Of Body Image And Human Appearance, 2012, pp. 233-237. Elsevier, doi:10.1016/b978-0-12-384925-0.00035-3. Accessed 19 Jan 2021.

[6] Munro, Alistair. Delusional Disorder. Cambridge University Press, 1999.

[7] Tamminga, Carol. “Delusional Disorder – Psychiatric Disorders – MSD Manual Professional Edition”. MSD Manual Professional Edition, 2020,

[8] Skelton, Mike et al. “Treatments For Delusional Disorder”. Cochrane Database Of Systematic Reviews, 2015. Wiley, doi:10.1002/14651858.cd009785.pub2. Accessed 19 Jan 2021.

[9] Winokur, George. “Delusional Disorder (Paranoia)”. Comprehensive Psychiatry, vol 18, no. 6, 1977, pp. 511-521. Elsevier BV, doi:10.1016/s0010-440x(97)90001-8. Accessed 19 Jan 2021.

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