Diseases and Disorders

The Neuropharmacology of Schizophrenia

Vilena Lee


Schizophrenia is a psychiatric disorder that requires lifelong treatment. The causes of schizophrenia are not certain, however scientists believe that the neurotransmitters dopamine and glutamate play a role in increasing the risk of developing schizophrenia. One method of treating schizophrenia is with  antipsychotic medication. Antipsychotic medication works by inhibiting the effects of neurotransmitters (primarily dopamine) on the brain, and this can alleviate symptoms such as mood swings, hallucinations, and delusions.

 

General Overview

    Schizophrenia is an illness that is classed as a chronic and psychiatric disorder. Characterized by severe hallucinations, delusions, cognitive impairment, sleep disturbances, and the inability to make decisions, schizophrenia is detrimental to one’s brain and body.  Globally, schizophrenia affects approximately 21 million people. Treatment is available, however, the disorder cannot be cured entirely.

    Schizophrenia occurs in approximately 1% of the United States general population [1].  However, if a person has a first-degree relative who suffers from schizophrenia, such as a parent or sibling, the chances of him suffering from the same disease increase to roughly 10%. Also, the risk of developing the disorder is higher with identical twins. If one twin has schizophrenia, the other twin has a 40-65% chance of development as well. Symptoms of the illness tend to occur between ages 16 and 30, however people typically do not develop schizophrenia beyond age 45 [2]. Men usually develop symptoms of schizophrenia earlier than women; men will show symptoms of schizophrenia in their late teens and early 20s, while women will begin showing symptoms in their late 20s and early 30s.

Causes

    Scientists have not isolated a single cause of schizophrenia.  Some research studies suggest that schizophrenia may be due to flawed neuronal development as a fetus {3}.  Other studies suggest that environment, as well as genetics and brain chemistry, interact in such a way that causes an increased risk of schizophrenia. Researchers believe that an issue with naturally occurring brain chemicals, such as dopamine and glutamate, may contribute to schizophrenia due to the discovery of abnormalities in these chemicals in schizophrenia patients [4].

    Dopamine and glutamate are neurotransmitters, which are chemicals released by neurons to send signals to other nerve cells.  Dopamine is responsible for controlling the brain’s reward and pleasure centers, as well as regulation of emotional responses and movement. Glutamate is an extremely powerful neurotransmitter, known as a “excitatory” neurotransmitter. Glutamate plays a role in learning and memory for the brain, however, it can also be extremely damaging as it tends to over excite cells, leading to cell death [5]. Scientists have theorized that both dopamine and glutamate levels in the brain can play a role in developing schizophrenia. By using the drug phencyclidine (PCP) to induce psychotic symptoms, scientists have noticed that by blocking neurotransmission at N-Methyl-D-Aspartate (NMDA)-type glutamate receptors, cognitive disturbances resembling that of schizophrenia can be produced [6].  With dopamine, scientists have theorized that too much of the neurotransmitter can result in the development of schizophrenia. The support of this theory stems from the fact that antipsychotic medications, which can be used to treat schizophrenia, operate by blocking dopamine receptors in the brain [7].

 

Treatment

    Even if symptoms have seemingly gone away, Schizophrenia requires lifelong treatment because there is no cure. Antipsychotic drugs are the most common method of treatment for schizophrenia, with the goal being to control and alleviate symptoms at the lowest possible dosage. Antipsychotic drugs are believed to help with symptoms of schizophrenia by affecting the brain’s production of dopamine.

    There are two types of antipsychotic drugs: second-generation antipsychotics and first-generation antipsychotics. Second-generation antipsychotics tend to be preferred because they pose a smaller threat of serious side effects than first-generation antipsychotics, that can have serious long-term side effects, often irreversible. One example of such effects is a movement disorder called “tardive dyskinesia”. This disorder makes one’s facial, tongue, and neck muscles move uncontrollably and can be permanent. On the other hand, first-generation antipsychotics tend to be more generic, thus being cheaper than second-generation antipsychotics. When long-term treatment is necessary, it is not uncommon for a patient to choose to take first-generation antipsychotics over second-generation antipsychotics solely due to price.

    Antipsychotic drugs work by altering the effect of certain chemicals in the brain, primarily dopamine. By altering the effect that dopamine has on the brain, antipsychotic medication can reduce the chances of experiencing hallucinations, delusions and extreme mood swings [8]. After starting antipsychotic medication, it can take 2-4 weeks before symptoms are being alleviated. In order to prevent relapses, treatment through medication for schizophrenia is continued long-term. Side effects of antipsychotic drug treatment include drowsiness, weight gain, dry mouth, and blurred vision. Out of 10 people who take antipsychotic medication for schizophrenia, 8 will experience improvement of their symptoms. In the end, the facts stack up to support the presence of a multitude of benefits that antipsychotic medications can bring to schizophrenic patients.


References


  1. Henderson, Dr Roger. (23/June/2015) “Antipsychotics. Drugs - How Do They Work? Medicine Info.”Antipsychotics. Drugs - How Do They Work? Medicine Info | Patient, Patient.info. patient.info/health/antipsychotic-medicines. Retrieved: 10/11/2017.

  2. Swierzewski, Stanley. (15/10/2013) “Schizophrenia Causes.” Schizophrenia Causes - Schizophrenia - HealthCommunities.com. www.healthcommunities.com/schizophrenia/causes.shtml. Retrieved: 25/10/2017.

  3. (23/Oct/2017)6. (2013) Schizophrenia. In: Diagnostic and Statistical Manual of Mental Disorders DSM-5. 5th ed. Arlington, Va.: American Psychiatric Association. http://www.psychiatryonline.org. Retrieved: 23/10/2017.

  4. (18/11/2014)“About Glutamate Toxicity.” HOPES Huntington's Disease Information, Stanford University,, web.stanford.edu/group/hopes/cgi-bin/hopes_test/about-glutamate-toxicity/. Retrieved: 1/11/2017.

  5. (2/2016) Schizophrenia. National Institute of Mental Health. http://www.nimh.nih.gov/health/topics/schizophrenia/index.shtml. Retrieved: 9/11/2017.

  6. Nordqvist, Christian. (24/3/2017) “Schizophrenia: Symptoms, Causes, and Treatments.” Medical News Today, MediLexicon International. www.medicalnewstoday.com/articles/36942.php. Retrieved: 9/11/2017.

  7. Hung, Y. (26/10/2017) “Risk Factors for Readmission in Schizophrenia Patients Following Involuntary Admission.” PloS One., U.S. National Library of Medicine. www.ncbi.nlm.nih.gov/pubmed/29073180?_ga=2.173334694.46878196.1511061503-917081783.1511061503. Retrieved: 11/11/2017.

  8. (19/4/2017) “Schizophrenia.” Psychology Today, Sussex Publishers, www.psychologytoday.com/conditions/schizophrenia. Retrieved: 11/11/2017.

Vilena Lee

Vilena Lee


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