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Relationship of Neurotransmitters and Depression

Updated on December 29, 2011


The purpose of this paper is to examine different articles on the types of neurotransmitters that play a role in the treatment of depression. The first article aim was to study and investigate the relationship between plasma glutamate, glutamine and gamma-aminobutyric acid (GABA) levels in female patients with major depression treated with S-citalopram or fluoxetine. Concluding that people with higher levels of GABA where less likely to exhibit signs of depression. The second article reviews the published research on the efficacy of neurotransmitter precursors in treating depression, highlights the findings of studies, and discusses issues regarding the interpretation of those findings. It was found that neurotransmitter precursors were successful in treating depression. The conclusion from these articles states that regulating the neurotransmitters of the monoamines group and increasing levels of GABA is effective at treating symptoms of depression.


Depression currently affects 16% of Americans. This has been one of the new diseases that started in the twentieth century. Depression has no single cause. It results from a mixture of problems, such as trauma and stress, a person’s conditions, their personality type, and even genetics. Some people have no idea why they are depressed. No matter the cause, depression is just not external. It is caused from imbalance changes in the brain. This imbalance is chemical that carries signals in your brain and nerves called neurotransmitters.

Effects of Depression

Events can trigger depression in all people, such as losing a job or a bad relationship. When these events are resolved most people come out of the depression easily and quickly. Some people however cannot. Others have no external reason for their depression. Depression can affect everyone, but some groups are more affected than others. One factor is age. Older people may lose loved ones and have to adjust to living alone. They may become physically ill and unable to be as active as they once were. These changes can all contribute to depression. Another is gender. Women are two times likely to become depressed then men. Women’s depression may be due to hormonal changes brought on by puberty, menstruation, menopause, and pregnancy. Men can suffer from depression and are more likely to go undiagnosed. They typical do not seek help, and suicide is common risk for men with depression.

There are many physical effects of depression. Depression can cause an increase in anxiety (more common in women) and anger (more common in men). People also have a loss of interest in activates they enjoy such as hobbies and sexual activity. A depressed person weight can fluctuate up or down and will experience sleeping problems such as insomnia. Sever depression can lead to physical sickness and thoughts or attempts of suicide.

Importance of Neurotransmitters

A neurotransmitter is a chemical that is released form one neuron to another and has an excitatory or inhibitory effect (Carlon 2008, p30). There are many neurotransmitters that play a role in depression; Serotonin plays one of the most important roles. Serotonin helps regulate mood and is important for feelings of well-being. Other neurotransmitters involved are dopamine, norepinephrine, and epinephrine (also called adrenaline). All four of these neurotransmitters belong to a group of chemical compounds called monoamines. They are all similar in there make up and can affect many of the same things.

There has been new research that the amino acid gamma-aminobutyric acid or GABA plays a role in depression (Winter 2010). GABA does serve a roll of a neurotransmitter but unlike the monoamines it is not synthesized from other amino acids. For example Serotonin is synthesized from the amino acid tryptophan, and dopamine, norepinephrine, and epinephrine are synthesized from tyrosine.

1st Article Review

I have reviewed two articles that explain how the lack of certain neurotransmitters causes depression and how certain drugs can increase these neurotransmitters. The first article explains the effects of the neurotransmitters serotonin and norepinephrine. The second article explants what roll GABA plays in depression.

The first article is titled Use of Neurotransmitter Precursors for Treatment of Depression. This article reviews different research on the efficacy of neurotransmitter precursors in treating depression. The two neurotransmitters studied are serotonin and norepinephrine. The paper states that insufficient active of the serotonin and norepinephrine is a central element of the model of depression held by neurobiologists (Myers 2000, p64).

The paper uses different studies from around the world to drawl its conclusion. Most of the studies took place from the 1970 to 2000. The group size varied and includes populations from Europe, Japan, and the USA. Groups were given drugs to increase serotonin and norepinephrine levels and monitored from 3 weeks to over a year. The measurement involved a test given before and after treatment such as Hamilton Rating Scale for Depression.

For the studies of serotonin, drugs where given that contain 5-HTP (5-Hydroxtryptophan) which synthesizes the amino acid tryptophan to serotonin. Each study evaluated conducted a double blind study with the control group receiving the drug with 5-HTP, and a control group receiving a placebo. The same procedures were used for the testing of norepinephrine with the exception that the drugs contained L-tryptophan: the synthesis for norepinephrine and dopamine.

The results suggest that synthesis level of serotonin did increase when these drugs were given. All groups given 5-HTP drugs scored higher on the Hamilton test after treatment. For norepinephrine the results had a lot smaller effect than serotonin, also there was less research done with norepinephrine. The results were better when both 5-HTP drugs and L-tryptophan drugs were given.

There was some limitation with the article. Most of the studies where in clinical situations and treated sever depression, although there were some outpatient studies. It was also a review of other peoples work. Not all testing procedures could be determined. There was a fluctuation of sample size from 18 to 155. The time the subjects were monitored was anywhere from a few weeks to a year.

2nd Article Review

The second article reviewed was The change in plasma GABA, glutamine and glutamate levels in fluoxetine- or S-citalopram-treated female patients with major depression. The reason for the study was to investigate the relationship between GABA levels in female patients with major depression. To see if increasing GABA leaves would improve depression with S-citalopram or fluoxetine.

13 female patients with severe depression were given S-citalopram (10 mg/day) or fluoxetine (20 mg/day). The measurement included the Hamilton and Beck Depression Inventory Scales before and after treatment. Blood samples were collected for the evaluation of plasma levels. Fifteen healthy female volunteers were also included in the study and blood samples were collected for the evaluation of normal plasma levels. They also took the Hamilton and Beck Depression Inventory Scales and received higher scores than the 13 patients before treatment.

There results stated: The plasma GABA levels of the healthy volunteers were higher whereas those for glutamate and glutamine were lower than the day zero samples of the patients. An increase in plasma GABA levels and a decrease in glutamate and glutamine levels were observed on the 10th day of treatment (Kucukibrahimoglu, Sygin, Cahskan, Kaplan, Unsal, and Goren 2009). When the GABA levels where increased; the patients test scores where higher. The article concluded thatthe findings may suggest that GABA, glutamate and glutamine play a role in depression and that plasma GABA may be used as a biomarker for treatment control.

The biggest limitation of this article was the sample size was small. Also, the subjects were all female. They all had severe depression and where staying at a treatment center. This article would have been hard to read with no prior knowledge of GABA. This trial needs to be tested on a larger population involving men and women with different levels of depression.

New Areas of Learning

After reviewing the articles, the newest ideal on treating depression was the increasing of GABA levels. The research of neurotransmitters took off in the 1950’s and most of the testing reviewed took place during the 1970’s and 1980’s. GABA research for depression is just now getting started. Another report just published in March 2010 stated; study of 85 people is the largest such research effort on GABA and major depressive disorder to date. It compared four groups: 25 individuals with treatment-resistant depression, 16 with major depression who were unmediated, 19 individuals with major depression who were successfully treated with medication and had normal mood, and a control group of 25 healthy individuals (Winter 2010, p.1).

The study’s findings where that people who were treatment-resistant to depression had lower levels of GABA. Therefore by increasing GABA levels patients are more likely to respond to other depression treatments. Future treatment may include a mix of drugs that increases levels of GABA so that drugs that increases the synthesis of serotonin will be more effective.

Summery and Opinion

All of the articles that where reviewed was relevant to the current treatment of depression. Each paper explained the reason for the testing and the sample base used. The paper on neurotransmitters was not new research but it was one of the first to summarize many different types of data to show the effeteness of neurotransmitter precursors. The study of GABA is a nice development on the treatment of depression. There does seem to be and increase of GABA studies in just this last year -2010.

My opining is that combining multiple researches on the effectiveness of neurotransmitter precursors was a good thing to do. There has been many experiments on how increasing serotonin helps fight depression. Comparing multiple studies from a span of 30 years and from different countries help prove the effectiveness of neurotransmitter precursors. There was some weakness in the report because of the lack of reliability of these sources.

I found the study of GABA the most interesting. The article reviewed went in to great detail on how the experiment was conducted. This was a very sound and exciting study. The biggest problem I saw was its samples size. The second article I found on GABA did have a larger sample size, but was very limited in the details of its findings. Both of the articles supported the idea that GABA helps fights and treats depression.

I believe that depression is easily treatable. Getting support from friends or a professional can help. There are times when that is not enough. Taking medication to alter the chemical imbalance may be the only way. I believe a person should try professional help first, as long as the depression is not life threatening, before pharmaceuticals.


As we saw, there are many different factors for the cause of depression; such as external factors, demographic factors, and chemical imbalances. Depression can cause many physical ailments and cause a person to live an unhealthy life. This disease can also lead to a complete withdraw from society leading to take of one’s own life.

Scientists have been trying to find ways to treat depression. It started with earlier research involving neurotransmitters to recent research involving GABA. It was found that increasing the levels of serotonin by introducing drugs wit 5-HTP and L-tryptophan will treat the symptoms of depression. By increasing GABA levels, patients do show improvement of their symptoms. Also people may be more receptive to depression treatment when GABA levels are higher.


Myers S. 2000, Use of neurotransmitter precursors for treatment of depression alternative Medicine Review vol. 5 #1 p.64 - 71.

Winter P.2010 Critical brain chemical shown to play role in severe depression Burrill Canadian Biotech News Vol 19 #8 p1 -2.

Kucukibrahimoglu, Sygin, Cahskan, Kaplan, Unsal, and Goren 2009. The change in plasma GABA, glutamine and glutamate levels in fluoxetine- or S-citalopram-treated female patients with major depression Marmara University school of Medicine Truky.

Carlson N. 2008 Foundations of physiological psychology 7th ed. Pearson Boston


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