Dopamine and Psychosis

Psychosis is a mental health disorder where an individual perceives or understands things differently from how other people do.

Dopamine

Image Credit: SergeyTarasov/Shutterstock.com

The two main symptoms are delusions and hallucinations. In the case of delusion, a person strongly believes in the truth of things that other people around them do not. One common delusion a person with psychosis may have is believing that people are planning to harm them.

In the case of hallucination, the individual hears, sees and sometimes even smells, feels or tastes things that are not there. One common example of hallucination is hearing voices.

When a person experiences delusions and/or hallucination, they can become very distressed and may start to change their behaviour. The occurrence of psychotic symptoms is often called a psychotic episode.

What causes psychosis?

Psychosis can be caused by a mental (psychological) condition, a general medical condition, or alcohol or drug misuse.

The cause of psychosis may be a mental health condition such as schizophrenia, bipolar disorder or severe anxiety, stress, or depression. The cause of the psychosis often determines what type of symptoms a person has.

Grandiose delusions are common in bipolar disorder and persecutory delusions are common in schizophrenia and depression. Grandiose delusions refer to when someone believes they have more power or authority than they do, such as believing they are a world leader or can revive dead people.

Persecutory delusions refer to conspiratorial thinking, where someone believes someone in authority is trying to harm them, for example.

Psychosis may also be caused by a general health condition such as Parkinson’s disease, malaria, multiple sclerosis or a brain tumor. Other causes include substance misuses such as drinking too much alcohol or taking drugs such as cocaine, MDMA or amphetamine.

A psychotic episode can also be triggered by suddenly stopping taking drugs or drinking alcohol after having done so for a long time. More rarely, psychosis can manifest as a side effect of taking certain medications or overdosing on them.

The ”dopamine hypothesis”

Scientists have conducted a lot of research into the effects of psychosis on the brain and the brain changes that may trigger psychotic episodes. They believe that the neurotransmitter dopamine plays a key role.

A neurotransmitter is a chemical agent that nerve cells use to transmit information to other nerve cells or muscle or gland cells. Dopamine modulates many brain functions, with dopamine pathways regulating motor control, motivation, interest, reward and activities such as walking and talking. Impairment of such brain functions may underlie the symptoms of psychosis.

Evidence that has led researchers to posit “the dopamine hypothesis” in conditions such as schizophrenia and bipolar disorder is based on several sources, including studies of brain scans and drugs that affect dopamine levels in the brain.

The dopamine hypothesis in schizophrenia

Schizophrenia is the leading cause of admissions to mental health hospitals and it accounts for even more of the permanent populations in such hospitals.

It is a severe and often chronic condition that is associated with more severe levels of impairment and personality disorder than in any other mental health condition. The main symptoms of schizophrenia include hallucinations, delusions, incoherent thought processes, a reduced ability to feel normal and a withdrawal from reality.

Although understanding the neurobiology of schizophrenia still presents a challenge, one feature that remains unchanged is the involvement of dopamine dysfunction.

Disruption to the dopamine system is the result of dopamine dysfunction in the following brain regions: the striatum, the prefrontal cortex, the hippocampus, and the substantia nigra.

In the case of schizophrenia, the dopamine hypothesis proposes that dopamine transmission is overactive in the mesolimbic areas and underactive in the prefrontal cortex. Dopamine dysregulation is also seen in the amygdala, which is involved in emotional processing.

Studies of positron emission tomography (PET) scans have also found differences in the dopamine system in certain brain regions between patients with schizophrenia and neuropsychiatric healthy individuals. In particular, the dopamine system is overactive in the hippocampus among patients with schizophrenia.

The dopamine hypothesis in bipolar disorder

Bipolar disorder is a common mental health condition characterized by changes in mood, which is characterized by episodes of feeling manic and overactive, but patients may also experience depressive episodes in bipolar disorder. Episodes of depression or mania can last for days or weeks.

Although the neurobiological mechanisms underlying bipolar disorder are not fully understood, the dopamine hypothesis has been a key theory for more than 40 years.

A 2017 systematic review published in Molecular Psychiatry, which looked at findings from pharmacological and biomedical imaging studies, found that the studies supported the hypothesis that a state of hyperdopaminergic underlies mania and that increased dopaminergic transporter levels underlie depression.

Interestingly, Oliver Howes and colleagues found that, according to the pharmacological evidence, both dopamine agonists and antidopaminergics may improve symptoms in bipolar depression.

The researchers say the evidence suggested a model where increased dopamine D2/3 receptor levels in the striatum would increase dopaminergic neurotransmission and lead to mania, while increased dopamine transporter (DAT) levels in the striatum would reduce dopaminergic function and cause depression.

According to the researchers, this suggests that the pathological mechanism underlying bipolar disorder may be failed dopamine receptor and transporter homeostasis. If this model could be confirmed, they add, it would have implications for the development of new therapeutic approaches such as decreasing synthesis in mania and inhibiting DAT in depression.

Other neurotransmitters

Recent research has suggested that dopamine perturbations alone may not fully account for the clinical features of psychosis. Ongoing research aims to determine what role, if any, serotonin, acetylcholine, glutamate, and GABA may play in psychosis.

Sources

Overview. Psychosis. NHS 2019. Available at: https://www.nhs.uk/conditions/psychosis/

Scott, JG et al. Dopamine, psychosis, and schizophrenia: the widening gap between basic and clinical neuroscience. Translational Psychiatry 2018;  8, 30 (2018) DOI:10.1038/s41398-017-0071-9. Available at: https://www.nature.com/articles/s41398-017-0071-9

Meyer-Lindenberg, A et al. Dopamine and Psychosis: Theory, Pathomechanisms, and Intermediate Phenotypes. Neurosci Biobehav Rev. 2010; 34(5): 689–700. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2838993/

Gos, T et al. The Role of Dopamine in Schizophrenia from a Neurobiological and Evolutionary Perspective: Old Fashioned, but Still in Vogue. Front Psychiatry 2014; 5: 47. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032934/

Howes, OD et al. The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment. Molecular Psychiatry 2017; 22: 666–679. Available at: https://www.nature.com/articles/mp201716

Schizophrenia. Encyclopedia Britannica. Available at: https://www.britannica.com/science/mental-disorder/Schizophrenia

Further Reading

Last Updated: Jan 23, 2020

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Robertson, Sally. (2020, January 23). Dopamine and Psychosis. News-Medical. Retrieved on May 18, 2021 from https://www.news-medical.net/health/Dopamine-and-Psychosis.aspx.

  • MLA

    Robertson, Sally. "Dopamine and Psychosis". News-Medical. 18 May 2021. <https://www.news-medical.net/health/Dopamine-and-Psychosis.aspx>.

  • Chicago

    Robertson, Sally. "Dopamine and Psychosis". News-Medical. https://www.news-medical.net/health/Dopamine-and-Psychosis.aspx. (accessed May 18, 2021).

  • Harvard

    Robertson, Sally. 2020. Dopamine and Psychosis. News-Medical, viewed 18 May 2021, https://www.news-medical.net/health/Dopamine-and-Psychosis.aspx.

Comments

  1. Jess Butler Jess Butler United States says:

    I have a friend who abuses amphetamines and I have repeatedly seen the dopaminergic effects played out in a manner that perfectly mimics my bipolar changes. When the friend is "speeding" it's just like my "mania" episodes; when they run out of the amphetamines, they act and look like my "depressive" side.
    The mania is pretty self-explanatory, exhibiting increased activity, speaking very rapidly, twitching, racing thoughts, and anorexia. With the withdrawal from the drug they will sleep, sometimes for days, talk and process information very slowly and dully, and eat (mostly carbohydrates and so-called comfort food).
    Researchers should think outside the box in this particular subject and take advantage of the untapped resources available. Also interesting would be a longitudinal study investigating the long-term effects of amphetamines upon the whole dopaminergic system in drug users to correlate their decreasing functionality with that of Parkinson's patients who lose their capabilities naturally instead of chemically.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
You might also like... ×
Study uncovers how the brain learns from subconscious stimuli