Delusional Disorder

Definition | Classification (ICD-10 and DSM-5) | Aetiology | Risk Factors | Clinical Presentation | Investigations | Management | When to Refer | References

Definition

Delusional Disorder is a psychiatric condition characterised by the presence of one or more delusions lasting for at least one month. Unlike schizophrenia, delusional disorder is not typically associated with other psychotic symptoms, such as hallucinations or significant cognitive impairment. The delusions are usually non-bizarre and involve situations that could occur in real life, such as being followed, poisoned, or having a disease.

Classification (ICD-10 and DSM-5)

Delusional Disorder is classified under the following diagnostic criteria:

ICD-10 Classification

In the ICD-10, Delusional Disorder is classified under:

• F22.0 - Delusional Disorder: This category includes persistent delusions of persecution, jealousy, or somatic delusions without the presence of other psychotic symptoms such as hallucinations, incoherence, or significant affective flattening.

DSM-5 Classification

In the DSM-5, Delusional Disorder is classified under:

• 297.1 (F22) - Delusional Disorder: This diagnosis requires the presence of one or more delusions for at least one month. The individual’s functioning is not markedly impaired, and behaviour is not obviously bizarre or odd. If hallucinations are present, they are not prominent and are related to the delusional theme.

Aetiology

The exact cause of delusional disorder is not fully understood, but it is believed to result from a combination of genetic, neurobiological, and environmental factors:

• Genetic Factors: A family history of delusional disorder, schizophrenia, or other psychotic disorders may increase the risk, suggesting a genetic predisposition.
• Neurobiological Factors: Imbalances in neurotransmitters, particularly dopamine, and abnormalities in brain structure may contribute to the development of delusional disorder.
• Psychosocial Stressors: Stressful life events, such as the loss of a loved one, social isolation, or immigration, may trigger the onset of delusional disorder in vulnerable individuals.
• Personality Traits: Individuals with certain personality traits, such as suspiciousness or paranoia, may be more prone to developing delusional disorder.

Risk Factors

Several factors increase the likelihood of developing delusional disorder:

• Family History: A family history of delusional disorder, schizophrenia, or other psychotic disorders.
• Age: Delusional disorder typically begins in middle to late adulthood, although it can occur at any age.
• Social Isolation: Individuals who are socially isolated or have limited social support may be at higher risk.
• Personality Disorders: Individuals with personality disorders, particularly paranoid, schizoid, or schizotypal personality disorders, are at increased risk.
• Substance Use: Substance abuse, particularly stimulants such as cocaine or amphetamines, can contribute to the development of delusional symptoms.

Clinical Presentation

Delusional disorder presents with the following key features:

Types of Delusions

• Persecutory Delusions: The belief that one is being conspired against, cheated, spied on, followed, poisoned, or harassed.
• Jealous Delusions: The belief that one’s partner is unfaithful, often leading to accusations without real evidence.
• Erotomanic Delusions: The belief that another person, often of higher status, is in love with the individual.
• Somatic Delusions: The belief that one has a physical defect or medical condition, despite evidence to the contrary.
• Grandiose Delusions: The belief that one has exceptional abilities, wealth, or fame.
• Mixed Delusions: A combination of two or more types of delusions without a predominant theme.

Impact on Functioning

• Preserved Functioning: Unlike schizophrenia, individuals with delusional disorder often maintain relatively normal functioning in other areas of life, such as work and social interactions, except where directly affected by the delusion.
• Non-Bizarre Behaviour: The behaviour is not obviously odd or bizarre, although it may be influenced by the delusional beliefs (e.g., avoiding certain places due to a persecutory delusion).

Investigations

The diagnosis of delusional disorder is primarily clinical, based on a detailed history and mental health assessment. Additional investigations may include:

• Psychiatric Assessment: A thorough mental health evaluation, including the use of structured interviews and rating scales, to assess the nature and impact of the delusions.
• Medical History and Physical Examination: To rule out other medical conditions that could cause delusional symptoms, such as neurological disorders or substance use.
• Laboratory Tests: Blood tests, including thyroid function tests and toxicology screening, to exclude medical conditions or substance use that may present with delusional symptoms.
• Neuroimaging: Brain imaging, such as MRI or CT scans, may be used to rule out structural brain abnormalities that could contribute to the symptoms.

Management

The management of delusional disorder typically involves a combination of pharmacotherapy, psychological therapies, and social support:

Pharmacotherapy

• Antipsychotic Medications: Antipsychotics, such as risperidone, olanzapine, or aripiprazole, are often the first line of treatment to reduce the intensity of delusions. The choice of medication may depend on side-effect profiles and patient preference.
• Adjunctive Treatments: In some cases, antidepressants or anxiolytics may be used to manage co-occurring symptoms of depression or anxiety.

Psychological Therapies

• Cognitive Behavioural Therapy (CBT): CBT can help individuals challenge and reframe their delusional beliefs, develop coping strategies, and reduce distress associated with the delusions.
• Supportive Therapy: Provides emotional support, helps build insight, and encourages medication adherence and engagement in treatment.
• Family Therapy: Involves the family in the treatment process, providing education and support to help manage the condition and reduce the impact on relationships.

Social Support

• Case Management: A case manager can provide ongoing support, helping to coordinate care, manage crises, and connect individuals with social services.
• Occupational Therapy: May help individuals maintain employment and daily functioning, particularly if the delusions impact work or social activities.
• Peer Support Groups: Participation in peer-led support groups can provide a sense of community and reduce feelings of isolation.

When to Refer

Referral to a specialist mental health service or psychiatrist is necessary in the following situations:

• Initial diagnosis or suspected delusional disorder requiring comprehensive assessment and initiation of treatment.
• Severe or treatment-resistant delusional disorder that does not respond to standard therapies, requiring specialised interventions.
• Presence of co-occurring mental health conditions, such as severe depression or anxiety, that require more intensive management.
• Significant impairment in daily functioning, including difficulties in self-care, social interactions, or occupational performance.
• Risk of harm to self or others, necessitating urgent intervention and possible hospitalisation.

References

1. World Health Organization (1992) ICD-10 Classification of Mental and Behavioural Disorders. Available at: https://www.who.int/classifications/icd/en/bluebook.pdf (Accessed: 26 August 2024).
2. American Psychiatric Association (2013) Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). Available at: https://www.psychiatry.org/psychiatrists/practice/dsm (Accessed: 26 August 2024).
3. National Institute for Health and Care Excellence (2024) Psychosis and Schizophrenia in Adults: Prevention and Management. Available at: https://www.nice.org.uk/guidance/cg178 (Accessed: 26 August 2024).

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