Causes of Delusions

People who experience delusions have a distorted perception of reality. They may believe they are being persecuted, when in reality no one is pursuing them. A delusional person might believe someone is following them, when no one has such motives. The delusions are as varied as the people who suffer from it. Several causes contribute to the onset of delusions, including drug use, psychotic disorders, mood disorders or dementia.

Drug Abuse

• Long-term use of marijuana often results in delusions.

  Illicit drugs, such as marijuana, can be a cause of delusions in drug abusers. Drug abusers who engage in drug use such as marijuana for several years become at risk of developing delusional disorders. Some studies have concluded that marijuana use is not as harmless as once perceived, according to Bloomberg.

Psychotic Illnesses

• Persons who suffer delusions have difficulty separating reality from fiction.

  Psychotic disorders are normally characterized by the sufferer experiencing paranoia and delusions. Psychotic illnesses include those such as schizophrenia, schizoaffective disorder and delusional disorder. A person with delusional disorder might perceive, for instance, that he has a life-threatening disease when none is present. Delusions in persons with delusional disorder usually last at least a month.

Mood Disorders

• Untreated bipolar or depression illnesses result in delusional thinking.

  Mood disorders include those such as depression and bipolar disorder, which can trigger the onset of delusions. Mood disorders are disorders of the brain, which result in abnormal behavior and thoughts. Such illnesses usually provoke false beliefs in the mind of the sufferer.

Dementia

• Dementia is one of several causes of delusional thinking in citizens who have Alzheimer's disease.

  Dementia includes diseases of the brain that include memory loss and mental impairment. Alzheimer's disease accounts for many cases of dementia. Common delusions experienced by those with Alzheimer's disease include misplacing an item and believing someone stole it or believing a trip to the doctor is an attempt to force them into a nursing home. In essence, the patient with dementia has a distorted perception of reality.