The term psychosis is frequently applied to abnormal conditions of the mind in which people lose contact with reality, experiencing delusional beliefs or hallucinations, as is frequently observed in the behavior of schizophrenics. The brain chemical dopamine acts a signaling molecule or neurotransmitter, facilitating the transfer of information between brain cells in the form of electrical impulses. High brain dopamine levels have been associated with psychosis, particularly in patients who suffer from schizophrenia.
Drug Induced Psychosis
Amphetamine and cocaine drug abuse increases brain dopamine levels, inducing symptoms similar to those suffered by schizophrenics during psychotic episodes, highlighting a link between dopamine and psychosis, according to a March 2008 article published in the "Journal of Clinical Psychiatry."
Parkinson's Patients
The drug levodopa raises dopamine levels in the brain, and is frequently prescribed to patients with Parkinson's disease, a degenerative condition characterized by movement disorders that arise due to the breakdown of dopamine-stimulated neuronal pathways in the brain. As with cocaine and amphetamine abuse, psychotic episodes are also a frequent side effect of levodopa, reinforcing the link between raised brain dopamine levels and psychosis, according to a January 2004 article published in the "Journal of Geriatric Psychiatry and Neurology."
Blocking Dopamine Signaling
A group of drugs known as phenothiazines that include chlorpromazine are known to inhibit the binding of dopamine to receptors in brain cells, thereby reducing dopamine stimulated brain activity. Chlorpropazine is frequently prescribed as an antipsychotic, which effectively reduces symptoms of psychosis, most likely through the blocking activity of this drug on dopamine signaling in the brain, according to an October 2010 article published in "Clinical Schizophrenia & Related Psychoses."
Other Factors
Studies have shown that some patients administered with sizable doses of drugs that inhibit dopamine signaling in the brain do not experience reduced symptoms of psychosis, indicating factors other than dopamine most likely contribute to psychosis in these cases, according to an October 2010 article published in "Clinical Schizophrenia & Related Psychoses."
Secondary Effects
Although the dopamine-inhibiting drugs that stimulate brain activity often act to reduce levels of this neurotransmitter within a matter of minutes, the antipsychotic actions of these medicines do not alleviate symptoms of psychosis in patients until several days have passed in most cases. These delayed actions suggest that raised dopamine levels may be only indirectly responsible for causing psychosis, according to a September 2010 article published in "Journal of Pharmacological Sciences."
References
- PubMed: "Clinical Schizophrenia & Related Psychoses"; Thinking Glutamatergically: Changing Concepts of Schizophrenia Based Upon Changing Neurochemical Models; J. Kantrowitz, D. Javitt; October 2010
- PubMed: "Journal of Pharmacological Sciences"; Advanced research on dopamine signaling to develop drugs for the treatment of mental disorders; M. Itokawa et al.; September 2010.
- PubMed: "Journal of Clinical Psychiatry"; Substance Induced Psychosis: A clinical Conundrum; S. Mathias et al.; March 2008.
- PubMed: "Journal of Geriatric Psychiatry and Neurology"; Psychosis in Parkinson's Disease; D. Wint et al.; January 2004.
