Delusions are false beliefs that have no basis in reality; individuals hold on to these beliefs despite the existence of evidence to the contrary. Delusions are a symptom of psychosis and occur in some neurological and psychiatric disorders. High levels of the neurotransmitter dopamine, as well as insufficient levels of dopamine, are characteristic of certain disorders. The level of dopamine in your brain affects the existence of delusions.
Dopamine Hypothesis
The dopamine hypothesis indicates that excessive levels of dopamine are associated with psychotic features. It is based on the fact that drugs that increase dopamine levels, such as amphetamines, cause psychosis. In addition, the dopamine hypothesis is supported by the inclusion of dopamine in anti-psychotic medications. Anti-psychotic medications block dopamine receptors to prevent overproduction. As a result, symptoms of psychosis, such as delusions and hallucinations, are reduced.
Schizophrenia
Schizophrenia is a serious mental health disorder. According to the National Institute for Mental Health, schizophrenia affects approximately 1 percent of the U.S. population over age 18 in any given year. The paramount feature of schizophrenia is a break from reality, which is manifested by delusions. Although there is no cure for schizophrenia, there are a variety of medications to treat the symptoms and help reduce delusions. Olanzapine, quetiapine and risperidone are all anti-psychotic medications used to treat schizophrenia by blocking serotonin and dopamine receptors.
Parkinson's Disease
Parkinson's disease is a neurological condition characterized by tremors and a significant impairment in movement. Low levels of dopamine are a contributing factor to the development of this disease. Therefore, treatment for this disease involves medications that increase dopamine levels such as levodopa. However, delusions can occur as a side effect of such drugs. In a study published in April 2007 in the "Journal of Neurology," researchers found that delusions were more likely to occur in Parkinson's patients taking levodopa who had a younger age of onset.
Delusional Disorder
Delusional disorder involves the presence of one or more nonbizzare delusions. "The Diagnostic and Statistical Manual of Mental Disorders" describes "nonbizzare delusions" as beliefs that are conceivable and involve situations that are possible in reality such as being followed or deceived by a loved one. In a 2002 study published in "Neuropsychopharmacology," researchers found haloperidol, an anti-psychotic medication containing a high level of dopamine, was effective in treating delusions associated with delusional disorder. Delusions of persecution were especially supportive of the dopamine hypothesis.
References
- "Neuropsychopharmacology"; Delusional Disorder: Molecular Genetic Evidence for Dopamine Psychosis;Kiyoshi Morimoto et al.; 2002
- "The Diagnostic and Statisical Manual of Mental Disorders", 4th Edition, Text Revision; American Psychiatric Association; 2000
- National Institute of Mental Health: The Numbers Count: Mental Disorders in America
- The Medical News: Delusion Development
- PubMed.gov: Relationship between age and subtypes of psychotic symptoms in Parkinson's disease; G. Kiziltan et al.; April 2007
- CNS Spectrums: Beyond the Dopamine Hypothesis
