Depression is a recognized medical diagnosis and can potentially be a serious mental illness because it can increase the risks of suicidal ideations. Depression is characterized by specific common symptoms experienced over an extended period of time. The etiological (causative) of depression is multi-factorial with environmental, genetic and neurological/biological being the main contributing factors. Neurotransmitters, chemicals produced in the brain, are the key elements controlling mood and behavior when they bind to their specific receptors. These neurotransmitters have been linked to mood and its deficiency or dysfunctions can predispose a person to getting depression. Certain receptors play key roles in depression, such as, dopamine receptors, norepinephrine receptors and serotonin receptors.
Norepinephrine Receptors
In the 1960s, the theories were formulated and developed proposing the basis for depression was chemically-based. The "American Journal of Psychiatry" published an article in 1965 by Joseph J. Schildkraut M.D. who cited the symptoms of depression was attributed to a deficiency in norepinephrine production in the brain. Although norepinephrine has been shown to regulate mood in some individuals, in others the modulation of norepinephrine alone was not sufficient to alter mood. An article published in the 2000 "Journal of Clinical Psychiatry" by researcher PL Delgardo, supported the role that norepinephrine played in depression.
Serotonin Receptors
In the 1970s, the discovery of another neurotransmitter called serotonin gave another theory for depression. The theory stated that depression caused by a drop in serotonin levels will concomittantly permit a drop in norepinephrine, and result in symptoms of depression. This discovery allowed scientists to try to treat depression by modulating serotonin levels. Indeed the most common medications in use today are SSRI's (selective serotonin re-uptake inhibitors) which elevate the levels of serotonin in certain regions of the brain. According to the U.S. Food and Drug Administration, the SSRI medications are commonly used to manage and treat symptoms of depression in the United States.
Dopamine Receptors
A third neurotransmitter, called dopamine, also plays a major role in mood. Dopamine is the 'reward' neurotransmitter and is found in regions in the brain that stimulate and regulate feelings of reward and motivation. These drugs are involve with compulsive behaviors, such as drug abuse. Drugs that affect dopamine can be used in conjunction with other antidepressants. Due to their action on dopamine and the associated feeling of reward, they have a high potential for abuse and must be used with caution.
