44-Year-Old Shop Owner from Kalyan Treated for Delusional Disorder After Believing His Business Partner Was Plotting Against Him
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Delusional Disorder Case Study: Patient Background
This delusional disorder case study follows Suresh (name changed), a composite example that reflects how delusional disorder commonly shows up and how it is assessed and treated at Calida Rehab. The details are illustrative and do not describe any one identifiable person.
Suresh is a 44-year-old owner of an auto-parts shop in Kalyan. He is married and lives with his wife and their two children, aged 15 and 11. He built the shop over twenty years with the help of a business partner, Vinod (name changed), who looks after the supply side. For most of his life Suresh was known as hardworking, practical and careful with money. About fourteen months before he came to us, he began to feel that something was wrong at the shop. Over the next year that feeling hardened into a fixed belief that Vinod and a rival trader were secretly planning to push him out of the business, and that they were having him watched. Nothing his family, his accountant or his friends said could shake it. His wife brought him for help after he stopped eating or drinking anything prepared at the shop and began to go through the CCTV footage for hours every night.
Before the case itself, a short note. Delusional disorder is a mental health condition in which a person holds one or more fixed false beliefs, called delusions, for at least a month, without the other major features of schizophrenia such as ongoing hallucinations or disorganised speech. Away from the belief, the person often thinks, speaks and works quite normally, which is why the condition is so easily missed. It is not caused by a weak character or by overthinking. If you want the full picture, read our page on delusional disorder.
Symptoms: How Delusional Disorder Showed Up in Daily Life
The main symptom of delusional disorder is a delusion: a belief that is clearly false, that the person holds with complete conviction, and that does not change even when strong evidence is shown. Delusions can take different themes. Suresh had the most common one, the persecutory type, in which a person believes they are being cheated, followed, spied on or plotted against.
The delusional belief
- Feels certain that a particular person or group is working against them in secret
- Reads ordinary events, such as a car parked outside or a phone call that ends suddenly, as proof of the plot
- Cannot be reasoned out of the belief, and may become angry or withdrawn when doubted
- Thinks about the belief for much of the day
Changes in behaviour
- Checking, recording or guarding: locks, CCTV, phone, accounts
- Avoiding places, people or food linked with the belief
- Confronting or writing complaints about the person they suspect
- Poor sleep, tension and irritability that build over time
- Pulling away from friends, relatives and business contacts
What is usually not present
- Constant hallucinations, such as hearing voices that others cannot hear
- Jumbled speech or very disorganised behaviour
- A long period of low mood or high mood that explains the belief
In this case: Suresh was certain that Vinod and a rival trader were planning to take over his shop, that his phone was being tapped and that two men in a parked car outside were watching him. He changed the shop locks three times, stopped taking tea or snacks from the shop, and spent most nights reviewing CCTV clips. He argued openly with Vinod in front of customers, and two regular clients stopped coming. He slept four to five hours a night, lost weight and became short-tempered at home. Apart from this one theme, he still kept accounts correctly, spoke clearly and looked after his children. He had no thoughts of ending his life or of harming anyone, and this was checked carefully at assessment.
Why Delusional Disorder Is Often Missed for Years
Delusional disorder is uncommon. DSM-5-TR estimates a lifetime prevalence of about 0.2%, and it often first appears in middle adult life. Because the person can work, run a home and speak sensibly about everything else, families and even doctors may treat the belief as a quarrel, a personality quirk or plain suspicion. Most people with a delusion do not believe they are ill, and they rarely ask for help. It is usually a relative or a colleague who finally seeks it, often after a crisis.
Left untreated, delusions can lead to broken relationships, lost jobs and businesses, long-running disputes, poor sleep and, in some cases, risky or aggressive acts based on the belief. The earlier the person is helped, the less damage builds up, and the easier it is to build trust.
In this case: Suresh’s wife first thought he was under heavy business stress. His brother tried to prove the belief wrong by showing him bank statements and speaking to Vinod, but this made Suresh feel that even his own family was being fooled. For almost a year he refused to see a doctor, saying that he was not the one who needed help. It was only after the clients left and he began avoiding food that his wife persuaded him to come in, on the condition that it was for his sleep and his health.
Diagnosis: How Delusional Disorder Was Assessed at Calida Rehab
There is no blood test or scan that confirms delusional disorder. The diagnosis is made by a psychiatrist through a careful clinical assessment. At Calida Rehab this typically includes:
- A detailed interview about the belief itself: when it began, how strongly it is held, how much it fills the day and how it affects work and family
- Information from the family, with the person’s consent, about how things have changed and what the person has said and done
- A mental state examination to check speech, mood, thinking and perception, and to see whether hallucinations or disorganised thinking are present
- A risk assessment for suicide, for harm to others and for acting on the belief
- A medical check to rule out other causes, including thyroid problems, vitamin B12 deficiency, blood sugar problems, infections, head injury and brain conditions, with a brain scan if the doctor thinks it is needed
- Screening for alcohol, cannabis, stimulant and medicine use, which can cause suspicious or paranoid thinking
To diagnose delusional disorder, the psychiatrist looks for one or more delusions lasting at least one month; no pattern of schizophrenia, such as ongoing hallucinations or disorganised speech; daily functioning that is not badly affected apart from the direct effects of the belief; no major mood episode that explains it; and no other medical condition or substance as the cause. The condition is then named by its theme. See our pages on schizophrenia and psychosis disorder treatment to see how the conditions are told apart. Our schizophrenia case study shows a different pattern.
Result in this case: Suresh was diagnosed with delusional disorder, persecutory type. His thyroid, vitamin B12, blood sugar and brain scan were normal. He drank two to three drinks on some weekends, with no pattern of heavy use, and tests for other substances were negative. He showed no mood episode and no hallucinations. His mood was tense and his sleep was poor, both linked to the belief.
Treatment Plan for Delusional Disorder
Treatment of delusional disorder needs patience. Because the person does not feel ill, the first job is to build trust. At Calida Rehab the plan is made after the assessment, and the family is involved when the person agrees. Most plans combine the following.
Building trust first. The team does not argue with the belief or try to prove it wrong in the first weeks, because this usually makes the person feel more alone. Instead, the team starts from what the person does accept, such as poor sleep, constant tension and the toll on health and family, and offers help with those.
Medicines. The psychiatrist usually prescribes an antipsychotic medicine, started at a low dose and raised slowly. Medicines do not remove the belief overnight. They often reduce the fear, the preoccupation and the sleeplessness first, and the belief may then loosen over weeks or months. Response varies, and the plan is adjusted as needed. Pulse, blood pressure, weight, blood sugar, sleep and movement-related side effects are checked regularly. Never start, stop or change a dose on your own.
Talking therapies. Therapy helps the person look at their experiences gently, understand how stress and sleeplessness feed suspicion, and cope with fear without acting on it.
Family education. Families learn what delusional disorder is, why arguing does not help, and how to respond calmly.
Daily routine and rest. Fixed sleep and wake times, regular meals, light exercise and a structured day support every other part of the plan. Alcohol and other substances are kept out, because they can make suspicion worse.
In this case: Suresh was admitted to a structured four-week programme at Calida Rehab for assessment, stabilisation and therapy. He agreed to stay for help with sleep and stress. A low-dose antipsychotic was started and slowly increased, with regular checks of his weight, blood sugar and sleep. Staff did not challenge his belief about Vinod. They listened, took his worries seriously and focused on his fear and exhaustion. His wife and brother joined family sessions.
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Therapies Used in This Delusional Disorder Case Study
The therapies below were part of Suresh’s plan and are commonly used in the care of delusional disorder and other forms of psychosis.
- Supportive individual counselling: a steady, non-judging relationship in which the person feels heard, which is the base for all other therapy. See our individual counselling page.
- Cognitive Behavioral Therapy (CBT) for psychosis: over time, looks at the evidence for and against a belief, explores other explanations and builds coping skills for fear and stress. Read more on our CBT page.
- Psychoeducation: helps the person and family understand the condition, the medicines and the early signs that symptoms are returning
- Stress and sleep skills: breathing, relaxation and sleep routines, which reduce the tension that feeds suspicion
- Occupational therapy: rebuilds daily routine and a gradual return to work. See our occupational therapy page.
- Family therapy: sessions that help the family stay calm, avoid arguments about the belief and support treatment. See our family therapy page.
Follow-Up Care After the First Phase
Delusional disorder can come back, so care does not end when the first phase of treatment ends. Follow-up usually includes:
- Regular reviews with the psychiatrist to check the belief, mood, sleep and side effects, with more frequent reviews in the first months and wider gaps later
- Medicine review, since stopping medicines too early is a common reason for relapse
- Booster therapy sessions when stress, sleeplessness or old suspicions return
- A written plan with early warning signs and who to call, shared with the family
- Support with the return to work and with repairing relationships
Our delusional disorder page explains what ongoing care looks like.
Outcome: What Recovery Looks Like With Delusional Disorder
What changed for Suresh over the first three months:
- The belief: it did not vanish, but he held it less tightly. He could say that he sometimes wondered whether he had misread things, and he thought about it for a few minutes a day, not most of the day.
- Behaviour: he stopped reviewing CCTV through the night and went back to eating at the shop.
- Sleep and mood: he slept around seven hours at regular times, and his fear and irritability settled.
- Work: he returned part-time, then full-time. At his own request, the accounts were reviewed by an outside accountant, which helped him get on with work whatever he still thought.
- Family: arguments at home eased, and his wife said she felt she had her husband back.
It is worth being clear about what recovery means. In delusional disorder, a delusion does not always disappear completely. Success can mean that the belief causes much less fear, no longer rules the day, and no longer pushes the person into harmful acts. The person works, sleeps, eats and relates to others again.
What the first six months of treatment usually look like
- Month 1: assessment, diagnosis, trust-building, a short structured programme and a written plan
- Months 2 and 3: medicines are adjusted, therapy builds, and family sessions continue
- Months 4 to 6: gains settle in, and the team reviews what is working and what still needs support
This is a general guide. Every person moves at a different pace.
Key Takeaways from This Delusional Disorder Case Study
- Delusional disorder is a medical condition. It is not stubbornness, weakness or a character flaw.
- A person can look and act normally in most areas of life while holding a fixed false belief, which is why the condition is often missed.
- Arguing with or trying to disprove the belief usually makes things worse. Trust and calm come first.
- A proper diagnosis needs a full assessment to rule out medical causes, substance use and other mental illnesses.
- The best results usually come from medicines, talking therapy, family support and a steady daily routine together.
- Recovery often means the belief loses its hold, not that it disappears. Getting help early is still worth it.
When Should You See a Doctor?
Please speak to a doctor if a family member or you:
- Hold a belief with complete certainty that others cannot understand, such as being watched, cheated, poisoned or plotted against
- Spend much of the day thinking about it, checking, guarding or collecting proof
- Have stopped eating, sleeping or working normally because of it
- Have been pulling away from family, friends or colleagues, or keep making complaints or confronting people
- Have been drinking or using substances to cope with fear or suspicion
If you or someone you know talks about hurting themselves or someone else, do not wait. Call 112 in an emergency, or Tele-MANAS on 14416. You can also call our 24-hour helpline for a confidential conversation.
Delusional Disorder Case Study: Frequently Asked Questions
What is delusional disorder?
Delusional disorder is a mental health condition in which a person holds one or more fixed false beliefs, called delusions, for at least a month. Apart from the effects of the belief, the person often functions fairly normally.
How is delusional disorder different from schizophrenia?
In schizophrenia, a person usually has several symptoms together, such as ongoing hallucinations, disorganised speech and thinking, and a clear drop in daily functioning. In delusional disorder, the delusion is the main problem, and the person is otherwise much less affected.
What are the types of delusional disorder?
The main types are named after the theme of the delusion: persecutory, jealous, erotomanic, grandiose, somatic and mixed. The persecutory type, in which a person believes they are being harmed, followed or plotted against, is among the most common.
Why does the person not believe they are ill?
A delusion feels completely real to the person. Many people with delusional disorder lack insight into their illness, so they do not feel they need treatment. This is part of the condition and not stubbornness.
Should family members argue with the delusion?
No. Arguing or showing proof usually leads the person to feel that no one understands them, and may push them away from help. It is better to stay calm, listen, acknowledge the fear or stress they feel and encourage them to see a doctor.
How is delusional disorder treated?
Treatment usually combines antipsychotic medicines, talking therapy such as CBT for psychosis, family education and a steady daily routine. Building trust comes first, and the psychiatrist adjusts the plan as the person responds.
Can delusional disorder be cured?
Many people improve a great deal with treatment, but the condition can return, and some beliefs do not disappear completely. Treatment aims to reduce fear and preoccupation, protect relationships and work, and prevent relapse.
Is my information kept private?
Yes. Assessment and treatment details are confidential and are shared with family or employers only with your consent, except where there is a serious risk to safety.
Sources and Further Reading
This page is for information and is not a substitute for medical advice. The case described is a composite example, and details are illustrative. If you think you or someone close to you may have delusional disorder, please see a psychiatrist for a full assessment.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). 2022.
- National Institute for Health and Care Excellence. Psychosis and schizophrenia in adults: prevention and management (CG178). nice.org.uk/guidance/cg178
- Kiran C., Chaudhury S. Understanding delusions. Industrial Psychiatry Journal, 2009; 18(1): 3-18.