Biology 202
2000 First Web Report
On Serendip

It is estimated that in the United States about 19 million people or one in ten adults experience depression each year.  Nearly two-thirds do not get help for the disease and or receive the treatment they need.  They might be too embarrassed or ashamed to get help or they may not realize that they are depressed and need help.  Others think that depression is just part of life and their feelings of sadness will pass in time.  While most people experience depression at some time during their lives, depression that last more than a few weeks requires treatment (2).

That is the odd thing about depression.  Few of us think twice about going to the hospital to set a broken limb, because we know a health-care professional can help us.  It is the same for depression.  There is a long-running controversy about the cause of depression, which means no one, knows for sure: some say our personal history or experiences (psychology) cause depression, others say brain chemistry causes depression.  Yet others say that depression is caused by genetic predisposition (4).  Though all theories are valid and supported by various scientific findings, defining the cause of depression is complicated.  Obviously, no two individuals become depressed in the same way.  For example, one might become depressed from stress while another person might have a genetic predisposition to the disease.  To add to the complication of depression, there are various types of the illness. Furthermore, various combinations and severity of symptoms can cause depression and many people suffer only some traits associated with depression ((2)).

So what are the symptoms of depression? ((2)) · Persistent sad, anxious, or "empty" mood · Loss of interest or pleasure in activities, including sex · Restlessness, irritability , or excessive crying · Feelings of guilt, worthlessness, helplessness, hopelessness, pessimism · Sleeping too much or too little, early-morning awakening · Appetite and/or weight loss or overeating and weight gain · Decreased energy, fatigue, feeling " slowed down" · Thoughts of death or suicide, or suicide attempts · Difficulty concentrating, remembering, or making decisions · Persistent physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and chronic pain.

Treatment for depression is prevalent and given the time-effective.  Therapy can include medication, psychotherapy, and electroconvulsive therapy or ECT ((1)).  A prominent and widely used treatment for depression in the United States is drugs that correct biochemical imbalances ((2)).  Scientific findings have found neurotransmitters, norepinephrine, dopamine, and serotonin most involved with depression.  Pathways of these neurotransmitters lead into the hypothalamus responsible for the functions affected in depression (sleep, appetite, mood, and sexual interest).  Findings propose that when one is in a depressed state, the neurotransmitters wane.  When these neurotransmitters are low, the nervous system slows down, the brain’s functions are depressed, and depression is manifested ((4)).

For example, serotonin helps you feel relaxed and content.  But when serotonin levels drop one might become more agitated, anxious, impulsive, and sad.  Suppose you are taking an exam and you reach an unexpected snag.  As you feel yourself getting anxious, neurons send serotonin to neuro-receptors.  When the serotonin hits the neuro-receptor, it passes along the message that you should remain calm.  But if serotonin levels are too low the signal might not be as strong.  Thus, you remain stressed and perhaps become irritable ((4)). 

Some drugs that stabilize neurotransmitters are tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and the newer selective serotonin reuptake inhibitors (SSRIs).  Each acts on different chemical pathways of the human brain related to mood ((4)).  The first two mentioned are older and have many associated side affects such as drowsiness, weight change, nausea, and insomnia ((3)).  All of which might have further affect a depressed individual.  Thus, a new wave of drugs called Selective Serotonin Reuptake Inhibitors (SSRIs) have taken vogue and carry such house-hold names like Prozac, Paxil and Zoloft ((3)).  They work by allowing the serotonin molecules released by your brain to stay in the space between your neurons longer so you receptor cells can absorb and use the serotonin longer and more efficiently ((4)).  Interestingly enough both psychotherapy and drugs relieve depression in some cases, so the treatment does not clarify the causes.  My guess is that psychological factors play a role in almost all depressions and physiological (chemical) factors are a significant causal factors in some depressions, especially the very severe cases but my guess is as good as an others.

The challenge of understanding depression and providing relief to its considerable afflicted population has brought together a unique group of investigators with diverse backgrounds and differing primary focuses.  Approaches conceptualizing depression have taken the form biochemical theories, genetic studies, psychoanalytic models, animal models, as well as cognitive and behavioral formulations ((2)) ((4)).  Often the theory evolves from a consideration of a particular form of depression or from one or two of its discrete characteristics ((2)).  None of the theories clearly explain the totality of depression or reflect the diversity of depression.  Thus, depression is not a unitary phenomenon and brings about many questions.  Do all types of depression have common biochemical etiology?   Are the treatments truly affective or did the illness just run its natural course, and terminate?  Though many questions have been answered several more are yet to be resolved. 

Finally, education of the public may pave the way for some understanding, less stigmatizing, and more acceptance of depressions in all forms.  This small step might be the most crucial as it directly focuses on the victims of depression.

WWW Sources

2) NIMH Brochure on Depression

3) Drug treatment for Depression

4) The Neurobiology of Depression