Neurotransmitters Linked to Depressive Symptoms

Introduction

There is an undeniable relationship between monoamine neurotransmitters and depressive symptoms. Monoamine neurotransmitters are chemical messengers in the brain including serotonin, norepinephrine, and dopamine. Despite the overlap between these three, each has a distinct role. Serotonin aids in the regulation of overall mood and impacts learning, memory, and sleep cycles (Cleveland Clinic, 2022). Norepinephrine impacts stress responses by regulating attention and arousal. Dopamine is crucial in the brain’s reward pathway, influencing pleasure and motivation (Khalil et al., 2024). These three key neurochemicals have direct impacts on mood and behavior. It is critical to highlight that mental illness cannot be simplified to a neurobiological issue. Rather, it is best to approach all cases from a biopsychosocial perspective, a lens that examines the potential biological, psychological, and social roots of illness. However, a comprehensive understanding of the neurotransmitters associated with depression can indubitably lead to better treatment outcomes. This paper aims to educate people in the mental health field. Clinicians, psychiatrists, students, and researchers alike can benefit from better understanding the neurotransmitters linked to depression. This paper also intends to educate the community outside of these fields, such as people who have been diagnosed themselves (or know someone with depression) and want a comprehensive understanding of the neurobiological connection. To further understand this topic, it is beneficial to examine other research findings. In treatment, as research continues, the neurotransmitters related to specific depressive symptoms can be targeted, thus allowing symptoms to be alleviated. 

Current findings suggest that a relationship exists between neurotransmitters and specific depressive symptoms. It may be that each neurotransmitter regulates and causes a different symptom in the patient. Instead of targeting depression as a whole, antidepressant medication can be used to target specific symptoms (Nutt, 2008). Additionally, medication can target residual symptoms that are not due to a co-occurring diagnosis (Blier, 2013). If a depressive symptom is unresponsive to medication, an antidepressant that targets a different neurotransmitter may be more effective (Blier, 2013). Furthermore, physicians need to understand the links between neurotransmitters and depressive symptoms to predict better outcomes for their patients. With comprehension of this relationship, physicians can prescribe antidepressants with greater accuracy (Nutt, 2008). In understanding which neurotransmitters implicate which depressive symptoms, psychotropic medications can be prescribed with increased certainty about their effectiveness. Recent surveys conducted by the Center for Disease Control have shown that 13.1% of adolescents and adults in the United States currently battle with some form of depressive disorder (Brody & Hughes, 2025). Within this group, nearly 90% reported that their depressive symptoms create difficulties at work, school and in social activities. (Brody & Hughes, 2025). With increased comprehension of the link between neurotransmitters and depressive symptoms, patients can have intentional and effective treatment plans, promoting better well-being and social life.

This review examines the findings put forth in the field of biological psychology, intending to expose the direct linkage between monoamine neurotransmitters (dopamine, norepinephrine, and serotonin) and symptoms of major depressive disorder (MDD). The DSM-5 describes major depressive disorder as a distinct episode of at least two weeks (although most episodes last considerably longer) with drastic changes in affect, cognition, and neurovegetative functions with inter-episode remissions (American Psychiatric Association, 2013). If researchers can determine the neurotransmitters that affect certain depressive symptoms, then psychotropic medication can be prescribed with more efficacy.

Discussion

        Current research has identified a link between neurotransmitters and the regulation of moods and behaviors (Nutt, 2008). The following figure shows the three key monoamine neurotransmitters and their contributions to different moods and behaviors (Nutt, 2008).

Figure 1

Monoamine Neurotransmitter Regulation of Mood and Behavior

There are two components of depressive disorder: negative affect, and loss of positive affect. Negative affect means that the client is experiencing their life with negativity, viewing components of the world as hostile and malevolent. Alternatively, loss of positive affect means that the individual is experiencing anhedonia, the inability to find pleasure in activities that were previously enjoyable (Nutt, 2008). The client may also lose motivation to maintain routines that were once an integral part of their life. These two components manifest vastly different symptoms. Current research proposes that clients with negative affect may feel symptoms alleviated by the use of psychotropic medication that specifically targets norepinephrine and serotonin. This could potentially reduce feelings of anxiety and irritability, increasing overall mood. Furthermore, clients experiencing loss of positive affect may have symptoms greatly reduced by integrating dopamine-targeting medication (Nutt, 2008).

Another factor to consider is the treatment of residual depressive symptoms after seeking treatment. The following figure shows the percent of respondents who stated they had residual depressive symptoms (Blier, 2013).

Figure 2

Proportion of Responders Who Had Symptoms at Baseline That Persisted at Exit

Research shows that clients who seek treatment for depressive disorders are often left with residual symptoms (Blier, 2013). If a client’s persistent symptoms are unresponsive to psychotropic medication, they should be re-evaluated. If their residual symptoms fall into the category of negative affect, then the client may feel relief with medication that targets norepinephrine and serotonin. Alternatively, if the client’s symptoms fall into the loss of positive affect category, they may experience symptom reduction by medication that targets the dopamine system. Their treatment can only be effective following a thorough and accurate diagnosis. Unfortunately, even with a comprehensive evaluation, some clients continue to struggle with persistent symptoms of depression. Research shows that the incorporation of serotonin and norepinephrine reuptake inhibitors (SNRIs) may be beneficial in these cases (Blier, 2013). The most common antidepressants target serotonin (Blier, 2013). When psychotropic medications increase serotonin levels, they often simultaneously decrease dopamine and norepinephrine levels. (Blier, 2013). The client’s symptoms, either core or residual, need to be fully comprehended so that the right medications can be prescribed. When a client presents with negative affective symptoms, SNRIs may be the correct choice. By increasing both serotonin and norepinephrine levels, the client may experience decreased feelings of irritability, anxiety, and an increase in mood. This differs from solely using SSRIs (selective serotonin reuptake inhibitors) in the treatment of depression. Although SSRIs can be beneficial, a complete understanding of the client's symptoms is necessary prior to prescribing any antidepressants.

        The etiology of depressive disorder cannot be tied to one neurotransmitter. There are an array of aspects (including environmental, biological and genetic) that contribute to the development and course of depressive disorders. Continued research on the complex relationship between neurotransmitters and depressive symptoms can lead to better treatment interventions (Kalia, 2005). Moving forward, research should focus on the effects of psychotropic medications that target the specific neurotransmitter involved in the production of depressive symptoms. Continued research on the neurobiological causes of major depressive disorder can provide insight into better treatment options and patient outcomes. Targeting specific neurotransmitters can ultimately lead to symptom reduction. With competent care and individualized treatment plans, patients’ overall well-being can be greatly improved, leading to further success in different aspects of life including school, work and relationships.

References

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. Diagnostic and Statistical Manual of Mental Disorders, 5(5). https://doi.org/10.1176/appi.books.9780890425596

Blier, P. (2013). Neurotransmitter Targeting in the Treatment of Depression. The Journal of Clinical Psychiatry, 74(suppl 2), 19–24. https://doi.org/10.4088/jcp.12084su1c.04

Brody, D., & Hughes, J. (2025). Prevalence of depression in adolescents and adults: United States. National Center for Health Statistics, 527(527). https://doi.org/10.15620/cdc/174579

Cleveland Clinic. (2022). Serotonin. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22572-serotonin

Kalia, M. (2005). Neurobiological basis of depression: An update. Metabolism, 54(5), 24–27. https://doi.org/10.1016/j.metabol.2005.01.009

Khalil, B., Warrington, S. J., & Rosani, A. (2024). Physiology, Catecholamines. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK507716/

Nutt, D. J. (2008). Relationship of neurotransmitters to the symptoms of major depressive disorder. The Journal of Clinical Psychiatry, 69 Suppl E1(18494537), 4–7. https://pubmed.ncbi.nlm.nih.gov/18494537/