Example: Thinking you know more heart disease than a world famous heart surgeon who holds multiple patents for devices to help treat heart disease; to the point of even denying the legitimate credentials of the world famous heart surgeon.
https://www.webmd.com/schizophrenia/delusions-grandeur
Delusional disorder is a serious mental illness where you can’t tell the difference between what’s real and what’s not. Delusions, or false beliefs, comes in several types. Delusions of grandeur are one of the more common ones. It’s when you believe that you have more power, wealth, smarts, or other grand traits than is true. Some people mistakenly call it “illusions” of grandeur.
Some delusions might be about events that possibly could have happened, but actually didn’t or were exaggerated. Other delusions are clearly bizarre, such as insisting that an alien lives in your fridge.
Symptoms
Even some healthy people can hold unreasonably high opinions of themselves. But unlike them, someone with grandiose delusions is unshakably convinced that their delusions are true.
For example, you may believe that you:
Are a multimillionaire
Found a cure for cancer
Are related to a Hollywood celebrity
Other symptoms may include:
Change in your mood. You may be irritable, angry, or feel low.
Hallucinations. You see, hear, or feel things connected to your delusion that aren’t really there. For example, if you believe that you have a special relationship with God, you may hear God’s voice. Hallucinations aren’t very common with delusional disorders, and they tend not to last long.
Other than the delusion, someone with this condition doesn’t usually seem or act odd. But sometimes, the delusions can get serious enough to cause problems in their daily life.
Causes
Researchers don’t know exactly what causes delusions. Sometimes, delusions of grandeur can be a symptom of another mental illnesses, including bipolar disorder and schizophrenia.
Grandiose delusions rarely happen by themselves. Most often, you are likely to also have delusions of persecution, a related condition where you’re convinced that others are out to harm, conspire against, or otherwise mistreat you.
Several things may play a role in delusional disorders:
Mental illness in your family
An imbalance of brain chemicals called neurotransmitters
Stress
Drug abuse
Social isolation or lack of close relationships
Diagnosis
No test can confirm that you have a delusional disorder. But your doctor will take a detailed mental history and rule out other medical causes to make a diagnosis.
You have this or another type of delusional disorder if you meet these criteria:
You’ve had one or more delusions that lasted a month or longer.
You have not been diagnosed with schizophrenia.
You show obviously bizarre behavior other than your delusions.
If you’ve had any episodes of mania or depression, they didn’t last longer than your delusional periods.
Your delusions don’t stem from drugs, another medical condition, or a different mental disorder.
Treatment
It can be hard to get help for delusional disorder because you may not even understand that you have a problem. Or you may resist or have a hard time sticking to your treatment plan. But that’s the key to feeling better.
The main treatments are:
Medication. Doctors often prescribe medicine for psychotic symptoms, depression, or to stabilize your mood. But it’s unlikely that drugs alone will be enough to manage your condition.
Mental health therapy. Some types of “talk” therapy may help ease grandiose delusions. With cognitive behavioral therapy, for example, you can learn to recognize and change unhelpful behaviors.
Involuntary treatment. If your delusions put you in danger of hurting yourself of others, you may need to stay at a hospital or a treatment center until you’re stable. States and localities have different laws about when and for how long you can be forced to get treatment against your will.