Fixed Abnormal Beliefs (Delusions)

🧠 A fixed abnormal belief is a belief that is held with absolute conviction, is not amenable to reason or contrary evidence, and is out of keeping with the person’s cultural or educational background. 👉 Clinically, this is referred to as a delusion. It is a core feature of psychotic disorders but can also arise in organic illness.

📖 About

• Delusions are a type of thought content abnormality.
• They differ from normal beliefs in that they are fixed, false, and unshakeable.
• Can be bizarre (physically impossible, e.g., “aliens control my thoughts”) or non-bizarre (possible but untrue, e.g., “the police are following me”).

🧬 Pathophysiology

• Exact mechanism unclear but involves dysregulation of dopamine pathways (especially mesolimbic hyperactivity).
• Frontal and temporal lobe dysfunction implicated in impaired reality testing.
• Delusions may represent the brain’s attempt to make sense of abnormal perceptual experiences (e.g., hallucinations).

🧾 Types of Delusions

🔍 Clinical Assessment

• 📚 History: Onset, duration, impact on function, risk (e.g., violence, self-harm).
• 👪 Collateral: Essential — patients may lack insight.
• 🧠 Mental State Exam: Identify delusional content, associated hallucinations, thought disorder, or mood symptoms.
• ⚠️ Risk assessment: Persecutory or jealous delusions may drive aggression; nihilistic delusions may lead to self-neglect.

🧪 Investigations

• 🩸 Bloods: FBC, U&E, LFTs, TFTs, B12/folate, glucose.
• 💉 Toxicology: Drugs/alcohol screen.
• 🧲 Imaging: CT/MRI brain if atypical, late onset, or neurological signs.
• 📊 Cognitive screen: To rule out dementia or delirium.

🛠️ Management

• 💊 Antipsychotic medication (first-line: atypicals such as risperidone, olanzapine, quetiapine).
• 🧠 Psychological support (CBT for psychosis, reality testing, coping strategies).
• 👨‍👩‍👧 Family and social support – psychoeducation, safeguarding.
• ⚠️ Risk management: Admission if danger to self/others.
• 🔄 Treat underlying cause: e.g., steroids-induced psychosis → reduce/stop steroids.

🚩 Red Flags

• Command delusions instructing harm to self or others.
• New onset of delusions after age 40 → consider organic causes.
• Coexisting cognitive impairment or fluctuating consciousness (possible delirium/dementia).
• Marked aggression or agitation linked to persecutory beliefs.

🧑‍⚕️ Case Scenarios — Delusional Disorders

• Case 1 (Persecutory delusion in schizophrenia): A 22-year-old university student has become increasingly withdrawn and now insists that MI5 are monitoring his laptop and tracking his movements online. He avoids leaving the house because of these fears and shows no insight into the abnormality of his beliefs. This presentation is most consistent with persecutory delusions in early schizophrenia. He requires urgent psychiatric referral for assessment, initiation of antipsychotic therapy such as risperidone or olanzapine, and a full risk assessment to ensure his safety and that of others, ideally supported by an early intervention in psychosis team.
• Case 2 (Somatic delusion): A 47-year-old woman repeatedly attends emergency departments claiming that her intestines are “rotting,” despite multiple negative scans and blood tests. She remains fixed in her conviction and is distressed when reassured, often demanding surgical intervention. This picture suggests a somatic delusion, which may occur as part of a primary delusional disorder or severe mood disorder. Management involves careful exclusion of organic disease, followed by psychiatric review, initiation of antipsychotic therapy, and consideration of antidepressants if comorbid depression is identified, alongside consistent follow-up to reduce unnecessary admissions.
• Case 3 (Delusional disorder — jealous type): A 60-year-old man with no psychiatric history develops a fixed belief that his wife is being unfaithful. He has become increasingly suspicious, searches her belongings, and has displayed episodes of verbal aggression towards her. The absence of hallucinations or disorganised thought suggests a jealous type of delusional disorder rather than schizophrenia. Given the risks of harm to his partner, urgent psychiatric evaluation is required, with exclusion of organic causes such as dementia or substance misuse, and consideration of inpatient admission for risk management, initiation of antipsychotic therapy, and safeguarding measures involving his family and social services.

✅ Conclusion

Fixed abnormal beliefs (delusions) are a hallmark of psychosis. 🌟 Always exclude organic and substance causes in new presentations. ⚠️ Risk assessment is vital, particularly with persecutory, jealous, or command delusions. Early recognition and treatment improve outcomes and reduce harm.