{"formatVersion":"1.1","id":"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters","path":"/library/biology-of-depression-neurotransmitters","url":"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters","title":"Neurotransmitters and Depression","family":"Library detail","description":"Discover the causes of depression, including biological, psychological, and social factors.","language":"en-US","access":{"audience":"public","indexable":true},"provenance":{"sourceUrl":"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters","wordpressId":"4489","contentCompleteness":"complete","dateScope":"original-source"},"authors":[{"@type":"Person","@id":"https://www.mentalhealth.com/people/erin-george#person","name":"Erin L. George","url":"https://www.mentalhealth.com/people/erin-george"}],"dates":{"datePublished":"2024-05-31T23:31:29Z","dateModified":"2025-08-31T12:50:43Z"},"content":{"html":"<nav aria-label=\"Breadcrumb\" class=\"breadcrumbs\"><ol><li><a href=\"https://www.mentalhealth.com/\">Home</a></li><li><a href=\"https://www.mentalhealth.com/library\">Library</a></li><li><a href=\"https://www.mentalhealth.com/library/depression\">Depression</a></li><li><span aria-current=\"page\">Neurotransmitters and Depression</span></li></ol></nav><div class=\"article-page article-standard\" data-library-standard=\"\"><div class=\"article-main-grid\"><header class=\"article-heading\"><h1>Neurotransmitters and Depression</h1><p class=\"article-inline-credits\">Written by <a class=\"article-credit-person\" href=\"https://www.mentalhealth.com/people/erin-george\"><img alt=\"\" height=\"22\" loading=\"lazy\" src=\"https://www.mentalhealth.com/assets/optimized/3e6614c23a1205b91bc9e56a.jpg\" width=\"22\" decoding=\"async\">Erin L. George</a></p><div class=\"article-dates\"><span>Published on <time datetime=\"2024-05-31T23:31:29Z\">May 31, 2024</time></span><span aria-hidden=\"true\"> · </span><span>Updated on <time datetime=\"2025-08-31T12:50:43Z\">August 31, 2025</time></span></div></header><div class=\"article-jumpbar\"></div><div class=\"article-layout\"><div class=\"article-reading\"><article class=\"prose\" id=\"article-content\"><div class=\"article-intro\" data-source-field=\"hero\"><p>Depression, formally known as <a href=\"https://www.mentalhealth.com/library/major-depressive-disorder\" class=\"article-inline-link\" data-context-link=\"355\">major depressive disorder</a>, is a mental health condition characterized by a persistent depressed mood or a loss of pleasure or interest in activities you once enjoyed. </p><p>It can significantly affect your functioning at home, work, or school, and can cause many medical and emotional issues⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"1\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#depression\" data-reference-link=\"\" aria-label=\"Reference 1: American Psychiatric Association. (2020). What Is Depression? American Psychiatric Association. Accessed October 10 2026.\">[1]</a></sup>.,⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"2\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#diagnostic-statistical-manual-mental-disorders\" data-reference-link=\"\" aria-label=\"Reference 2: American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. (5th ed.). PsychiatryOnline. Accessed April 12 2025.\">[2]</a></sup> Depression is a complex psychiatric disorder without one cause—rather, its development is influenced by many interacting and compounding factors like genetics, individual biochemistry, environment, and personality⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"1\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#depression\" data-reference-link=\"\" aria-label=\"Reference 1: American Psychiatric Association. (2020). What Is Depression? American Psychiatric Association. Accessed October 10 2026.\">[1]</a></sup>.</p><p>A literal ton of research has been done on the <a href=\"https://www.mentalhealth.com/library/causes-of-depression\" class=\"article-inline-link\" data-context-link=\"353\">causes of depression</a>. Below is a brief discussion of the multiple biological, psychological, and social factors that have been identified as being related to the development of depression, with a particular focus on neurotransmitters as key messengers in the brain affecting mood and behavior.</p><p>In the context of the Diathesis-Stress hypothesis, the biological factors typically function as diatheses, the psychological factors may serve as diatheses or stressors, and sociological and lifestyle factors may tend to function as stressors or triggers.</p></div><figure class=\"article-feature\"><img alt=\"A man sits thoughtfully at a kitchen table.\" decoding=\"async\" height=\"675\" loading=\"eager\" src=\"https://www.mentalhealth.com/assets/optimized/f65d5f245af8278ca4c4d3d7.webp\" width=\"1200\" srcset=\"/assets/responsive/b4d30d1e48bf19e39a9a3fa0.webp 800w, /assets/optimized/f65d5f245af8278ca4c4d3d7.webp 1200w\" sizes=\"(max-width: 800px) 100vw, 1200px\"></figure><section aria-labelledby=\"key-takeaways\" class=\"article-takeaways\"><h2 id=\"key-takeaways\">Key takeaways</h2><ul><li>Depression reflects interacting biological, psychological, and social influences rather than a single chemical imbalance.</li><li>The vulnerability-stress model describes how predispositions and environmental stressors can combine in the development of depression.</li><li>Serotonin, norepinephrine, dopamine, and other neurotransmitter systems are implicated in mood regulation and depressive symptoms.</li></ul></section><h2 id=\"what-is-the-diathesis-stress-model\">What is the Diathesis-Stress Model?</h2><p>This model, also referred to as the vulnerability-stress model, is a theory asserting that medical and mental health conditions are caused by a person’s genetic predisposition and how they experience stress. </p><p>Diathesis refers to the predisposition like genes or other biological factors and stress refers to environmental stressors like trauma that contributed to an onset of depression or other mental health condition. Both genes and environmental triggers can influence neurotransmitter production and levels in different people, which can then lead to depression⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"3\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#encyclopedia-personality-individual-differences\" data-reference-link=\"\" aria-label=\"Reference 3: Broerman R. (2018). Encyclopedia of Personality and Individual Differences. In: Zeigler-Hill V, Shackelford TK, eds. Springer International Publishing; 2018:1-3. doi:10.1007/978-3-319-28099-8_891-1. Springer. Accessed October 10 2026.\">[3]</a></sup>.</p><h2 id=\"biology-of-depression\">Biology of Depression</h2><p>You may have heard that <a href=\"https://www.mentalhealth.com/library/depression\" class=\"article-inline-link\" data-context-link=\"353\">depression</a> is the result of a simple chemical imbalance of brain chemicals. Although brain chemicals are certainly part of the cause, this explanation is too simplistic. Even just considering the biological dimension of depression, the brain has multiple layers of complexity.</p><h3 id=\"is-depression-biological\">Is Depression Biological?</h3><p>Yes, partially. Depression is a complex condition that involves biological, psychological, and environmental factors. There is evidence that suggests that depression has a biological basis. Research has shown that depression is associated with changes in the structure and function of the brain⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"4\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#harvard-health\" data-reference-link=\"\" aria-label=\"Reference 4: Harvard Health Publishing. (2022). [Referenced web resource]. Harvard Health. Accessed October 10 2026.\">[4]</a></sup>.</p><p>These changes can affect the production, function, and levels of neurotransmitters in the brain. The relationship between depression and neurotransmitters lies in the intricate interplay of chemicals in the brain that regulate mood, emotions, and well-being. </p><p>Neurotransmitters like serotonin, dopamine, and norepinephrine act as messengers, transmitting signals between nerve cells. With depression, there may be low levels of neurotransmitters like serotonin, which can result in symptoms like low mood, lack of pleasure, and disturbed sleep.</p><p>However, this “imbalance” is complex and multifaceted and is likely influenced by many biological, environmental, and genetic factors⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"4\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#harvard-health\" data-reference-link=\"\" aria-label=\"Reference 4: Harvard Health Publishing. (2022). [Referenced web resource]. Harvard Health. Accessed October 10 2026.\">[4]</a></sup>.</p><p>Additionally, genes can also play a role in the development of depression, and there is a higher risk of depression in individuals with a family history of the condition. Therefore, while depression has psychological and environmental factors, it is also a biological condition that can have a significant impact on a person's life.</p><h3 id=\"chemical-imbalances-and-depression\">Chemical Imbalances and Depression</h3><p>The concept of chemical imbalances in depression refers to disruptions in the normal levels of neurotransmitters, such as serotonin, dopamine, and norepinephrine.</p><p>While the theory of a simple, one-size-fits-all chemical imbalance causing depression has been challenged, research suggests that neurotransmitter dysregulation plays a nuanced role⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"4\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#harvard-health\" data-reference-link=\"\" aria-label=\"Reference 4: Harvard Health Publishing. (2022). [Referenced web resource]. Harvard Health. Accessed October 10 2026.\">[4]</a></sup>. Factors like genetics, environmental stressors, and individual variations in brain function contribute to this complex interplay, highlighting the need for a personalized understanding of the neurobiological underpinnings of depression.</p><section aria-label=\"Subject matter expert\" class=\"article-expert article-expert-inline\" data-expert-kind=\"related\" data-expert-layout=\"standard\"><p class=\"article-bio-role\">Subject matter expert</p><div class=\"article-expert-identity\"><a href=\"https://www.mentalhealth.com/people/simone-hoermann\" class=\"card-identity-photo\" aria-label=\"Simone Hoermann  Ph.D.\"><img alt=\"\" height=\"64\" loading=\"lazy\" src=\"https://www.mentalhealth.com/assets/optimized/5ffe249a46895c9a14f6074b.jpg\" width=\"64\" decoding=\"async\"></a><h2><a href=\"https://www.mentalhealth.com/people/simone-hoermann\">Simone Hoermann <span class=\"expert-credentials\">Ph.D.</span></a></h2></div><p class=\"article-expert-focus\">Personality disorders, anxiety, and depression</p></section><h2 id=\"neurotransmitters-and-depression\">Neurotransmitters and Depression</h2><p>The brain uses several chemicals as messengers to communicate with other parts of itself and with the nervous system. These chemical messengers, called neurotransmitters, are released and received by the brain's many nerve cells, which are also called neurons. Neurons are constantly communicating with each other by way of exchanging neurotransmitters. This communication system is essential to all of the brain's functions.</p><p>A tiny space called a synapse connects neurons to one another. In a simple scenario, one neuron (the sender) sends a neurotransmitter message across the synapse and the next neuron (the receiver) receives that message by way of a receptor embedded on its surface. </p><p>Receptors are tiny molecules in nerve cells that function like a lock on a door. Receptors have chemical channels with particular shapes, which perfectly match the shape of neurotransmitter molecules that are sent across the synapse.</p><p>When a \"matching\" neurotransmitter and receptor come into contact with each other, the neurotransmitter fits itself into the receptor molecule's channel. As a result, the receptor becomes activated or opened, just like when a key enters a lock and turns to open it. When there are no neurotransmitter molecules around to unlock the receptors, the receptors remain in a closed or inactive state.</p><p>In music, it's not just the notes that make up a melody; it is also the spaces or rests between the notes that make each note stand out and be distinct. It's exactly the same with regard to neurotransmitters and synapses. </p>\n<p>There needs to be some quiet time between neurotransmitter messages for those messages to have any meaning. It is important that receptors be allowed to reset and deactivate between messages so that they can become ready to receive the next burst of neurotransmitters. </p><p>In order to achieve this \"resetting\", the receptors relax and release their captured neurotransmitters back into the synapse where about 90% of them get taken up again (in a process called reuptake) by the original sending neuron.</p><p>The neurotransmitters are then repackaged and reused the next time a message needs to be sent across the synapse. Even though this seems like a complicated set of steps, this entire information transmission cycle occurs in the brain within a matter of seconds. Any problem that interrupts the smooth functioning of this chain of chemical events can negatively impact both the human brain and nervous system.</p><span id=\"how-does-depression-affect-neurotransmitters-\" class=\"section-anchor-alias\" data-section-alias=\"how-does-depression-affect-neurotransmitters\" aria-hidden=\"true\"></span><h2 id=\"how-does-depression-affect-neurotransmitters\">How Does Depression Affect Neurotransmitters?</h2><p>Depression affects neurotransmitters in the brain, such as serotonin and norepinephrine, which can lead to changes in a person's mood, energy, and overall mental state</p><p>Studies have shown that in people with depression, there may be a decrease in the amount of these neurotransmitters available, which can cause symptoms like loss of interest or pleasure in activities, changes in appetite or sleep, and feelings of <a href=\"https://www.mentalhealth.com/library/anxiety\" class=\"article-inline-link\" data-context-link=\"355\">anxiety</a>.</p><p><a href=\"https://www.mentalhealth.com/library/antidepressants\" class=\"article-inline-link\" data-context-link=\"358\">Antidepressants</a> work by increasing the availability of these neurotransmitters, which can help alleviate symptoms and improve mood. Understanding the role of neurotransmitters in depression is important for developing effective treatments for severe depression and helping patients lead a better quality of life.</p><span id=\"what-neurotransmitter-causes-depression-\" class=\"section-anchor-alias\" data-section-alias=\"what-neurotransmitter-causes-depression\" aria-hidden=\"true\"></span><h2 id=\"what-neurotransmitter-causes-depression\">What Neurotransmitter Causes Depression?</h2><p>Serotonin, norepineprhine, and dopamine are the main neurotransmitters involved in depression⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"5\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#pathophysiology-depression-do-we-have-any-solid-evidence-interest\" data-reference-link=\"\" aria-label=\"Reference 5: Hasler G. (2010). Pathophysiology of depression: do we have any solid evidence of interest to clinicians? World psychiatry : official journal of the World Psychiatric Association (WPA), 9(3), 155–161. Wiley. Accessed October 10 2026.\">[5]</a></sup>.</p><p>Depression is a mood disorder that affects many people. Research has shown that the levels of certain neurotransmitters, which are chemicals that send signals in the brain, can be linked to depression. One such neurotransmitter is serotonin, which plays a role in regulating mood, sleep, and appetite</p><p>Another neurotransmitter, norepinephrine, is also believed to be involved in depression. Studies have found changes in the levels of these and other neurotransmitters in people with depression. </p><p>Antidepressant medications are often used to treat depression by increasing the levels of these neurotransmitters in the brain. Understanding the role of neurotransmitters in brain development and depression is important for finding effective treatments.</p><p>Depression has been linked to problems or imbalances in the brain with regard to the neurotransmitters serotonin, norepinephrine, and dopamine. The evidence is somewhat indirect on these points because it is very difficult to actually measure the level of neurotransmitters in various brain regions of a person's brain.</p><p>What we do know is that antidepressant medications (used to treat the symptoms of depression) are known to act upon these particular neurotransmitters and their receptors. We'll talk more about antidepressant medications in the treatment section of this article.</p><h3 id=\"norepinephrine-and-depression\">Norepinephrine and Depression</h3><p>Norepinephrine contributes to motivation and reward and can influence anxiety and blood pressure. Its effects depend on the brain systems involved; depression cannot be explained by a single neurotransmitter level⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"6\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#norepinephrine-nexus-arousal-motivation-relapse\" data-reference-link=\"\" aria-label=\"Reference 6: Harvard Health Publishing. (n.d.). Depression: Chemicals and communication. Harvard Medical School. Harvard Health. Accessed October 10 2026.\">[6]</a></sup>.</p><p>Another line of research has investigated linkages between the <a href=\"https://www.mentalhealth.com/library/stress\" class=\"article-inline-link\" data-context-link=\"355\">stress response</a>, hormones, depression, and norepinephrine.</p><p>Norepinephrine helps our bodies to recognize and respond to stressful situations. Researchers suggest that people who are vulnerable to depression may have a norepinephrinergic system that doesn't handle the effects of stress very efficiently.</p><h3 id=\"dopamine-and-depression\">Dopamine and Depression</h3><p>Dopamine supports movement, motivation, and reward processing. Changes in these systems may be relevant to depressive symptoms, but loss of pleasure does not by itself demonstrate a dopamine deficiency⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"6\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#norepinephrine-nexus-arousal-motivation-relapse\" data-reference-link=\"\" aria-label=\"Reference 6: Harvard Health Publishing. (n.d.). Depression: Chemicals and communication. Harvard Medical School. Harvard Health. Accessed October 10 2026.\">[6]</a></sup>.</p><h3 id=\"serotonin-and-depression\">Serotonin and Depression</h3><p>The neurotransmitter serotonin is involved in regulating many important physiological (body-oriented) functions, including sleep, aggression, eating, sexual behavior, and mood. Serotonin is produced by serotonergic neurons. </p><p>Current research suggests that a decrease in the production of serotonin by these neurons can cause depression in some people, other mood disorders, and more specifically, a mood state that can cause some people to feel suicidal.</p><p>In the 1960s, the \"catecholamine hypothesis\" was a popular explanation for why people developed depression. This hypothesis suggested that a deficiency of the neurotransmitter norepinephrine (also known as noradrenaline) in certain areas of the brain was responsible for creating depressed mood. More recent research suggests that there is indeed a subset of depressed people who have low levels of norepinephrine.</p><p>For example, autopsy studies show that people who have experienced multiple depressive episodes have fewer norepinephrinergic neurons than people who have no depressive symptoms or history of depressive behavior.</p><p>However, research results also tell us that not all people experience mood changes in response to decreased norepinephrine levels. Some people who are depressed actually show hyperactivity within the neurons that produce norepinephrine. More current studies suggest that in some people, low levels of serotonin trigger a drop in norepinephrine levels, which then leads to depression.</p><h3 id=\"other-neurotransmitters-and-depression\">Other Neurotransmitters and Depression</h3><p>Other chemical messengers have different roles in brain communication:⁠<sup class=\"citation-group\"><a class=\"article-citation\" data-reference-number=\"6\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#norepinephrine-nexus-arousal-motivation-relapse\" data-reference-link=\"\" aria-label=\"Reference 6: Harvard Health Publishing. (n.d.). Depression: Chemicals and communication. Harvard Medical School. Harvard Health. Accessed October 10 2026.\">[6]</a><a class=\"article-citation\" data-reference-number=\"7\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#cholinergic-regulation-mood-basic-clinical-studies-emerging-therapeutics\" data-reference-link=\"\" aria-label=\"Reference 7: Dulawa, S. C., &amp; Janowsky, D. S. (2019). Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics. Molecular psychiatry, 24(5), 694–709. Nature. Accessed October 10 2026.\">[7]</a></sup></p><ul class=\"wp-block-list\">\n<li><strong>Glutamate:</strong> An excitatory messenger that helps neurons pass signals onward.</li>\n<li><strong>GABA:</strong> An inhibitory messenger that reduces neural activity and is involved in anxiety regulation.</li>\n<li><strong>Acetylcholine:</strong> A messenger involved in learning and memory.</li>\n</ul></article><div class=\"article-endmatter\"><section class=\"article-sources\" data-reference-list=\"\" data-reference-style=\"author-date-title-source\" data-source-references=\"\" id=\"references\"><h2 id=\"references-2\">References</h2><ol><li id=\"depression\" value=\"1\" data-reference-number=\"1\" data-reference-format=\"393\">American Psychiatric Association. (2020). <em class=\"reference-title\">What Is Depression?</em> <a href=\"https://www.psychiatry.org/patients-families/depression/what-is-depression?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">American Psychiatric Association</a>. Accessed October 10 2026.</li><li id=\"diagnostic-statistical-manual-mental-disorders\" value=\"2\" data-reference-number=\"2\" data-reference-format=\"393\">American Psychiatric Association. (2013). <em class=\"reference-title\">Diagnostic and statistical manual of mental disorders.</em> (5th ed.). <a href=\"https://psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">PsychiatryOnline</a>. Accessed April 12 2025.</li><li id=\"encyclopedia-personality-individual-differences\" value=\"3\" data-reference-number=\"3\" data-reference-format=\"393\">Broerman R. (2018). <em class=\"reference-title\">Encyclopedia of Personality and Individual Differences.</em> In: Zeigler-Hill V, Shackelford TK, eds. Springer International Publishing; 2018:1-3. doi:10.1007/978-3-319-28099-8_891-1. <a href=\"https://link.springer.com/rwe/10.1007/978-3-319-28099-8_891-1?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">Springer</a>. Accessed October 10 2026.</li><li id=\"harvard-health\" value=\"4\" data-reference-number=\"4\" data-reference-format=\"393\">Harvard Health Publishing. (2022). <em class=\"reference-title\">[Referenced web resource].</em> <a href=\"https://www.health.harvard.edu/mind-and-mood/what-causes-depression?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">Harvard Health</a>. Accessed October 10 2026.</li><li id=\"pathophysiology-depression-do-we-have-any-solid-evidence-interest\" value=\"5\" data-reference-number=\"5\" data-reference-format=\"393\">Hasler G. (2010). <em class=\"reference-title\">Pathophysiology of depression: do we have any solid evidence of interest to clinicians?</em> World psychiatry : official journal of the World Psychiatric Association (WPA), 9(3), 155–161. <a href=\"https://onlinelibrary.wiley.com/doi/10.1002/j.2051-5545.2010.tb00298.x?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">Wiley</a>. Accessed October 10 2026.</li><li id=\"norepinephrine-nexus-arousal-motivation-relapse\" value=\"6\" data-reference-number=\"6\" data-reference-format=\"393\">Harvard Health Publishing. (n.d.). <em class=\"reference-title\">Depression: Chemicals and communication.</em> Harvard Medical School. <a href=\"https://www.health.harvard.edu/depression/depression-chemicals-and-communication?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">Harvard Health</a>. Accessed October 10 2026.</li><li id=\"cholinergic-regulation-mood-basic-clinical-studies-emerging-therapeutics\" value=\"7\" data-reference-number=\"7\" data-reference-format=\"393\">Dulawa, S. C., &amp; Janowsky, D. S. (2019). <em class=\"reference-title\">Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics.</em> Molecular psychiatry, 24(5), 694–709. <a href=\"https://www.nature.com/articles/s41380-018-0219-x?utm_medium=referral&amp;utm_campaign=libra&amp;utm_content=external_resource&amp;utm_id=site-library-biology-of-depression-neurotransmitters&amp;utm_source=mentalhealth.com\" target=\"_blank\" rel=\"nofollow noopener noreferrer\" class=\"reference-source\">Nature</a>. Accessed October 10 2026.</li></ol></section><section class=\"article-about article-panel\"><h2 id=\"about-mentalhealth-com\">About MentalHealth.com</h2><p>MentalHealth.com helps people understand themselves, build healthier relationships, and access the right care. We bring together mental health education, diagnostics, and care management to support well-being throughout every phase of life.</p><div class=\"article-contributors\"><section class=\"article-bio\"><a href=\"https://www.mentalhealth.com/people/erin-george\" class=\"card-identity-photo\" aria-label=\"Erin L. George\"><img alt=\"\" height=\"64\" loading=\"lazy\" src=\"https://www.mentalhealth.com/assets/optimized/3e6614c23a1205b91bc9e56a.jpg\" width=\"64\" decoding=\"async\"></a><div><p class=\"article-bio-role\">Author</p><h3 id=\"erin-l-george\"><a href=\"https://www.mentalhealth.com/people/erin-george\">Erin L. George</a></h3><p class=\"article-bio-credentials\">MFT</p><p>Erin L. George, MFT, holds a master's degree in family therapy with a focus on group dynamics in high-risk families. As a court-appointed special advocate for children, she is dedicated to helping families rebuild relationships and improve their mental and behavioral health.</p><dl><div><dt>Published</dt><dd><time datetime=\"2024-05-31T23:31:29Z\">May 31, 2024</time></dd></div><div><dt>Updated</dt><dd><time datetime=\"2025-08-31T12:50:43Z\">August 31, 2025</time></dd></div></dl></div></section></div></section><section aria-label=\"Related community\" class=\"article-topic-community article-topic-community-end\"><a href=\"https://www.mentalhealth.com/community/depression\" class=\"card-identity-photo\" aria-label=\"Depression\"><img alt=\"\" class=\"topic-community-banner\" height=\"675\" loading=\"lazy\" src=\"https://www.mentalhealth.com/assets/optimized/91211a50ddeaa7fa8b3e0af9.webp\" width=\"1200\" decoding=\"async\" srcset=\"/assets/responsive/a4f14d631a3c579a02f683c8.webp 800w, /assets/optimized/91211a50ddeaa7fa8b3e0af9.webp 1200w\" sizes=\"(min-width: 961px) 236px, calc(100vw - 80px)\"></a><p class=\"topic-community-label\">Related community</p><h2><a href=\"https://www.mentalhealth.com/community/depression\">Depression</a></h2><p>A place for understanding depression and sharing perspectives on its impact on daily life.</p></section></div></div><aside aria-label=\"Article navigation and related information\" class=\"article-sidebar\" data-bounded-rail=\"\" tabindex=\"0\"><details class=\"article-contents\" data-expanded=\"false\" data-scrolled-past=\"false\" data-section-preview=\"3\" open=\"\"><summary><strong>Table of contents</strong><span aria-hidden=\"true\"></span><small data-current-section=\"\">Choose a section</small></summary><nav aria-label=\"Article contents\"><ol id=\"article-section-list\"><li><a aria-label=\"What is the Diathesis-Stress Model?\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#what-is-the-diathesis-stress-model\" title=\"What is the Diathesis-Stress Model?\">What is the Diathesis-Stress Model?</a></li><li><a aria-label=\"Biology of Depression\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#biology-of-depression\" title=\"Biology of Depression\">Biology of Depression</a></li><li><a aria-label=\"Neurotransmitters and Depression\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#neurotransmitters-and-depression\" title=\"Neurotransmitters and Depression\">Neurotransmitters and Depression</a></li><li><a aria-label=\"How Does Depression Affect Neurotransmitters?\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#how-does-depression-affect-neurotransmitters\" title=\"How Does Depression Affect Neurotransmitters?\">How Does Depression Affect Neurotransmitters?</a></li><li><a aria-label=\"What Neurotransmitter Causes Depression?\" href=\"https://www.mentalhealth.com/library/biology-of-depression-neurotransmitters#what-neurotransmitter-causes-depression\" title=\"What Neurotransmitter Causes Depression?\">What Neurotransmitter Causes Depression?</a></li></ol><button aria-controls=\"article-section-list\" aria-expanded=\"false\" class=\"article-sections-toggle\" data-sections-toggle=\"\" type=\"button\">View more</button></nav></details></aside></div></div></div>","text":"Home Library Depression Neurotransmitters and Depression Neurotransmitters and Depression Written by Erin L. George Published on May 31, 2024 · Updated on August 31, 2025 Depression, formally known as major depressive disorder, is a mental health condition characterized by a persistent depressed mood or a loss of pleasure or interest in activities you once enjoyed. It can significantly affect your functioning at home, work, or school, and can cause many medical and emotional issues⁠[1].,⁠[2] Depression is a complex psychiatric disorder without one cause—rather, its development is influenced by many interacting and compounding factors like genetics, individual biochemistry, environment, and personality⁠[1]. A literal ton of research has been done on the causes of depression. Below is a brief discussion of the multiple biological, psychological, and social factors that have been identified as being related to the development of depression, with a particular focus on neurotransmitters as key messengers in the brain affecting mood and behavior. In the context of the Diathesis-Stress hypothesis, the biological factors typically function as diatheses, the psychological factors may serve as diatheses or stressors, and sociological and lifestyle factors may tend to function as stressors or triggers. Key takeaways Depression reflects interacting biological, psychological, and social influences rather than a single chemical imbalance. The vulnerability-stress model describes how predispositions and environmental stressors can combine in the development of depression. Serotonin, norepinephrine, dopamine, and other neurotransmitter systems are implicated in mood regulation and depressive symptoms. What is the Diathesis-Stress Model? This model, also referred to as the vulnerability-stress model, is a theory asserting that medical and mental health conditions are caused by a person’s genetic predisposition and how they experience stress. Diathesis refers to the predisposition like genes or other biological factors and stress refers to environmental stressors like trauma that contributed to an onset of depression or other mental health condition. Both genes and environmental triggers can influence neurotransmitter production and levels in different people, which can then lead to depression⁠[3]. Biology of Depression You may have heard that depression is the result of a simple chemical imbalance of brain chemicals. Although brain chemicals are certainly part of the cause, this explanation is too simplistic. Even just considering the biological dimension of depression, the brain has multiple layers of complexity. Is Depression Biological? Yes, partially. Depression is a complex condition that involves biological, psychological, and environmental factors. There is evidence that suggests that depression has a biological basis. Research has shown that depression is associated with changes in the structure and function of the brain⁠[4]. These changes can affect the production, function, and levels of neurotransmitters in the brain. The relationship between depression and neurotransmitters lies in the intricate interplay of chemicals in the brain that regulate mood, emotions, and well-being. Neurotransmitters like serotonin, dopamine, and norepinephrine act as messengers, transmitting signals between nerve cells. With depression, there may be low levels of neurotransmitters like serotonin, which can result in symptoms like low mood, lack of pleasure, and disturbed sleep. However, this “imbalance” is complex and multifaceted and is likely influenced by many biological, environmental, and genetic factors⁠[4]. Additionally, genes can also play a role in the development of depression, and there is a higher risk of depression in individuals with a family history of the condition. Therefore, while depression has psychological and environmental factors, it is also a biological condition that can have a significant impact on a person's life. Chemical Imbalances and Depression The concept of chemical imbalances in depression refers to disruptions in the normal levels of neurotransmitters, such as serotonin, dopamine, and norepinephrine. While the theory of a simple, one-size-fits-all chemical imbalance causing depression has been challenged, research suggests that neurotransmitter dysregulation plays a nuanced role⁠[4]. Factors like genetics, environmental stressors, and individual variations in brain function contribute to this complex interplay, highlighting the need for a personalized understanding of the neurobiological underpinnings of depression. Subject matter expert Simone Hoermann Ph.D. Personality disorders, anxiety, and depression Neurotransmitters and Depression The brain uses several chemicals as messengers to communicate with other parts of itself and with the nervous system. These chemical messengers, called neurotransmitters, are released and received by the brain's many nerve cells, which are also called neurons. Neurons are constantly communicating with each other by way of exchanging neurotransmitters. This communication system is essential to all of the brain's functions. A tiny space called a synapse connects neurons to one another. In a simple scenario, one neuron (the sender) sends a neurotransmitter message across the synapse and the next neuron (the receiver) receives that message by way of a receptor embedded on its surface. Receptors are tiny molecules in nerve cells that function like a lock on a door. Receptors have chemical channels with particular shapes, which perfectly match the shape of neurotransmitter molecules that are sent across the synapse. When a \"matching\" neurotransmitter and receptor come into contact with each other, the neurotransmitter fits itself into the receptor molecule's channel. As a result, the receptor becomes activated or opened, just like when a key enters a lock and turns to open it. When there are no neurotransmitter molecules around to unlock the receptors, the receptors remain in a closed or inactive state. In music, it's not just the notes that make up a melody; it is also the spaces or rests between the notes that make each note stand out and be distinct. It's exactly the same with regard to neurotransmitters and synapses. There needs to be some quiet time between neurotransmitter messages for those messages to have any meaning. It is important that receptors be allowed to reset and deactivate between messages so that they can become ready to receive the next burst of neurotransmitters. In order to achieve this \"resetting\", the receptors relax and release their captured neurotransmitters back into the synapse where about 90% of them get taken up again (in a process called reuptake) by the original sending neuron. The neurotransmitters are then repackaged and reused the next time a message needs to be sent across the synapse. Even though this seems like a complicated set of steps, this entire information transmission cycle occurs in the brain within a matter of seconds. Any problem that interrupts the smooth functioning of this chain of chemical events can negatively impact both the human brain and nervous system. How Does Depression Affect Neurotransmitters? Depression affects neurotransmitters in the brain, such as serotonin and norepinephrine, which can lead to changes in a person's mood, energy, and overall mental state Studies have shown that in people with depression, there may be a decrease in the amount of these neurotransmitters available, which can cause symptoms like loss of interest or pleasure in activities, changes in appetite or sleep, and feelings of anxiety. Antidepressants work by increasing the availability of these neurotransmitters, which can help alleviate symptoms and improve mood. Understanding the role of neurotransmitters in depression is important for developing effective treatments for severe depression and helping patients lead a better quality of life. What Neurotransmitter Causes Depression? Serotonin, norepineprhine, and dopamine are the main neurotransmitters involved in depression⁠[5]. Depression is a mood disorder that affects many people. Research has shown that the levels of certain neurotransmitters, which are chemicals that send signals in the brain, can be linked to depression. One such neurotransmitter is serotonin, which plays a role in regulating mood, sleep, and appetite Another neurotransmitter, norepinephrine, is also believed to be involved in depression. Studies have found changes in the levels of these and other neurotransmitters in people with depression. Antidepressant medications are often used to treat depression by increasing the levels of these neurotransmitters in the brain. Understanding the role of neurotransmitters in brain development and depression is important for finding effective treatments. Depression has been linked to problems or imbalances in the brain with regard to the neurotransmitters serotonin, norepinephrine, and dopamine. The evidence is somewhat indirect on these points because it is very difficult to actually measure the level of neurotransmitters in various brain regions of a person's brain. What we do know is that antidepressant medications (used to treat the symptoms of depression) are known to act upon these particular neurotransmitters and their receptors. We'll talk more about antidepressant medications in the treatment section of this article. Norepinephrine and Depression Norepinephrine contributes to motivation and reward and can influence anxiety and blood pressure. Its effects depend on the brain systems involved; depression cannot be explained by a single neurotransmitter level⁠[6]. Another line of research has investigated linkages between the stress response, hormones, depression, and norepinephrine. Norepinephrine helps our bodies to recognize and respond to stressful situations. Researchers suggest that people who are vulnerable to depression may have a norepinephrinergic system that doesn't handle the effects of stress very efficiently. Dopamine and Depression Dopamine supports movement, motivation, and reward processing. Changes in these systems may be relevant to depressive symptoms, but loss of pleasure does not by itself demonstrate a dopamine deficiency⁠[6]. Serotonin and Depression The neurotransmitter serotonin is involved in regulating many important physiological (body-oriented) functions, including sleep, aggression, eating, sexual behavior, and mood. Serotonin is produced by serotonergic neurons. Current research suggests that a decrease in the production of serotonin by these neurons can cause depression in some people, other mood disorders, and more specifically, a mood state that can cause some people to feel suicidal. In the 1960s, the \"catecholamine hypothesis\" was a popular explanation for why people developed depression. This hypothesis suggested that a deficiency of the neurotransmitter norepinephrine (also known as noradrenaline) in certain areas of the brain was responsible for creating depressed mood. More recent research suggests that there is indeed a subset of depressed people who have low levels of norepinephrine. For example, autopsy studies show that people who have experienced multiple depressive episodes have fewer norepinephrinergic neurons than people who have no depressive symptoms or history of depressive behavior. However, research results also tell us that not all people experience mood changes in response to decreased norepinephrine levels. Some people who are depressed actually show hyperactivity within the neurons that produce norepinephrine. More current studies suggest that in some people, low levels of serotonin trigger a drop in norepinephrine levels, which then leads to depression. Other Neurotransmitters and Depression Other chemical messengers have different roles in brain communication:⁠[6][7] Glutamate: An excitatory messenger that helps neurons pass signals onward. GABA: An inhibitory messenger that reduces neural activity and is involved in anxiety regulation. Acetylcholine: A messenger involved in learning and memory. References American Psychiatric Association. (2020). What Is Depression? American Psychiatric Association. Accessed October 10 2026. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. (5th ed.). PsychiatryOnline. Accessed April 12 2025. Broerman R. (2018). Encyclopedia of Personality and Individual Differences. In: Zeigler-Hill V, Shackelford TK, eds. Springer International Publishing; 2018:1-3. doi:10.1007/978-3-319-28099-8_891-1. Springer. Accessed October 10 2026. Harvard Health Publishing. (2022). [Referenced web resource]. Harvard Health. Accessed October 10 2026. Hasler G. (2010). Pathophysiology of depression: do we have any solid evidence of interest to clinicians? World psychiatry : official journal of the World Psychiatric Association (WPA), 9(3), 155–161. Wiley. Accessed October 10 2026. Harvard Health Publishing. (n.d.). Depression: Chemicals and communication. Harvard Medical School. Harvard Health. Accessed October 10 2026. Dulawa, S. C., & Janowsky, D. S. (2019). Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics. Molecular psychiatry, 24(5), 694–709. Nature. Accessed October 10 2026. About MentalHealth.com MentalHealth.com helps people understand themselves, build healthier relationships, and access the right care. We bring together mental health education, diagnostics, and care management to support well-being throughout every phase of life. Author Erin L. George MFT Erin L. George, MFT, holds a master's degree in family therapy with a focus on group dynamics in high-risk families. As a court-appointed special advocate for children, she is dedicated to helping families rebuild relationships and improve their mental and behavioral health. Published May 31, 2024 Updated August 31, 2025 Related community Depression A place for understanding depression and sharing perspectives on its impact on daily life. Table of contentsChoose a section What is the Diathesis-Stress Model? Biology of Depression Neurotransmitters and Depression How Does Depression Affect Neurotransmitters? What Neurotransmitter Causes Depression? 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It can significantly affect your functioning at home, work, or school, and can cause many medical and emotional issues.[1],[2] Depression is a complex psychiatric disorder without one cause—rather, its development is influenced by many interacting and compounding factors like genetics, individual biochemistry, environment, and personality.[1]\n\nA literal ton of research has been done on the causes of depression. Below is a brief discussion of the multiple biological, psychological, and social factors that have been identified as being related to the development of depression, with a particular focus on neurotransmitters as key messengers in the brain affecting mood and behavior.\n\nIn the context of the Diathesis-Stress hypothesis, the biological factors typically function as diatheses, the psychological factors may serve as diatheses or stressors, and sociological and lifestyle factors may tend to function as stressors or triggers.","text":"Depression, formally known as major depressive disorder, is a mental health condition characterized by a persistent depressed mood or a loss of pleasure or interest in activities you once enjoyed. It can significantly affect your functioning at home, work, or school, and can cause many medical and emotional issues.[1],[2] Depression is a complex psychiatric disorder without one cause—rather, its development is influenced by many interacting and compounding factors like genetics, individual biochemistry, environment, and personality.[1] A literal ton of research has been done on the causes of depression. Below is a brief discussion of the multiple biological, psychological, and social factors that have been identified as being related to the development of depression, with a particular focus on neurotransmitters as key messengers in the brain affecting mood and behavior. 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