Dopamine belongs to a class of molecules known as neurotransmitters, chemicals that act as messengers within the brain. Several critical brain systems require dopamine, including the movement, emotion and reward systems. Decreased levels of dopamine may be involved in several health conditions, including mental health conditions such as depression. However, the relationship between dopamine and depression appears to be complex and is proving quite challenging for researchers to fully elucidate.
Dopamine Background
One way different parts of your brain communicate with each other is by secreting and absorbing chemicals called neurotransmitters, such as dopamine. When a neuron needs to send a signal to a neighboring neuron, it releases a cocktail of neurotransmitters into the space between the neurons, also known as the synapse. The neurotransmitters then bind to specific receptors on the surface of the neighboring neuron, and these receptors activate various other signaling pathways inside the neuron that result in different activities.
Dopamine and Depression
During depression, the dopamine transmission lines in the brain are often impaired, resulting in faulty dopamine signaling, explains an article published in the December 2004 issue of the journal "Fundamental & Clinical Pharmacology." People suffering from depression often have low levels of dopamine in their brains, as well as low levels of a closely related neurotransmitter, norepinephrine. Often times, the sensitivity of the dopamine receptors are also changed, leading to a general malfunction of dopamine regulation. In some cases, the causes of these defaults in dopamine signally may be genetic, although researchers are still uncovering the role of genetic variation in depression, reports a paper published in the September-October issue of the "Journal of International Medical Research."
Treating Depression
These insights into dopamine and depression suggest that dopamine may be a suitable drug target for treating depression. Many of the most popular antidepressant medications target a different neurotransmitter, serotonin, and are known as selective serotonin reuptake inhibitors, or SSRIs. Medications that act on dopamine and norepinephrine, known as dopamine and norepinephrine reuptake inhibitors, or DNRIs, are under investigation as of 2011 as alternative options, a paper published in the journal "Primary Psychiatry" in 2007 explains. Future medications might combine both SSRIs and DNRIs with other types of inhibitors in an attempt to improve efficacy.
Complications
Treating depression by tweaking dopamine signaling may present several challenges. While increasing dopamine signaling appears to treat depression in some patients, other patients do not respond. Furthermore, in certain individuals, overstimulation of dopamine signaling appears to make depression worse, according to the article published in 2004 in "Fundamental & Clinical Pharmacology." Additional research is needed before doctors fully understand preciously how to treat depression by targeting dopamine.
References
- "Primary Psychiatry"; The Role of Dopamine and Norepinephrine in Depression; Donald S. Robinson; 2007
- "Fundamental & Clinical Pharmacology"; Dopamine, Depression and Antidepressants; Eric Dailly et al.; December 2004
- "Journal of Clinical Psychiatry"; The Role of Dopamine and Norepinephrine in Depression and Antidepressant Treatment; David J. Nutt; 2006
- University of Texas: Dopamine - A Sample Neurotransmitter
- "Journal of International Medical Resarch"; Polymorphisms in Genes Encoding the Serotonin and Dopamine Pathways in Two Sisters with Metachromatic Leukodystrophy; H. G. Kumperscak et al.; September-October 2008
