Biology 202
1999 First Web Reports
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What is Clinical Depression?

C. Murphy

People of all ages, backgrounds, and walks of life have felt depressed and unhappy at some time in their lives. These periods of sadness usually pass after a short time, but for some people, this feeling can remain for weeks, months, and even years. (1) This prolonged state of unhappiness is called major (or clinical) depression and is characterized by a persistent sad or "empty" mood, loss of interest in favorite activities, difficulty concentrating, and many other symptoms. It is not simply a mental state but an illness that interferes with the way people feel, function, and think.(2)

What are the symptoms of Clinical Depression?

The American Psychiatric Association considers people to have clinical depression if they exhibit at least five of the following symptoms almost every day for two weeks, and must show at least one of the first two criteria:

- depressed or sad mood most of the day

- markedly diminished interest or pleasure in daily activities

- substantial increase or decrease in appetite

- insomnia or excessive sleeping

- restlessness or slowness of movement

- fatigue or loss of energy

- feelings of worthlessness or excessive or inappropriate guilt

- difficulty concentrating, thinking, or making decisions

- recurrent thoughts of death or suicide

These symptoms must cause significant impairment of a person's ability to carry on with daily activities. Also, side affects of medication, drug abuse, a medical condition (thyroid abnormalities, for example), or bereavement, should be ruled out first. (3) A definite diagnosis of depression, however, requires an evaluation by a mental health specialist.

What causes Clinical Depression?

There has been debate between neurobiologists and psychologists on what causes depression - neurochemical imbalances or unfortunate experiences and negative thinking. (3) While successful drug therapies which act on neurotransmitters in the brain imply that depression is a neurobiological condition (4), the fact that such medications do not help about 20 percent of depression-sufferers seems to show that not all depression is due to such imbalances. Rather, depression is not caused by one single factor; it is most often caused by many different things. Genetics, biochemical factors, medicines and alcohol, developmental and other external factors, and relationships, marriage and children all have effect on the development of clinical depression. (5) The strongest hypotheses on the pathways to depression are in decreases in the activity of specific neurotransmitters, or the overactivity of certain hormonal systems. (3)

Who suffers from Clinical Depression?

More people suffer from depression than you might think. People of all ages, backgrounds, lifestyles, and nationalities get clinical depression. An estimated 35 to 40 million Americas living today will suffer from major depression at some time during their lives. (4) This is about 13 to 20 percent of all Americans. (1) About half of these individuals will experience recurring depression. (3) Despite being what authorities call "the nation's leading mental health problem" (6), depression is often misdiagnosed or undiagnosed, and therefore not treated. (4) Often as a result, about 25 percent of these people attempt suicide to end their suffering (6) and about 80 percent of all suicide deaths are of people who were profoundly depressed. (1) The Centers for Disease Control and Prevention reported in 1996 that suicide was the ninth leading cause of death in the United States (30,862 people), however, these figures are considered a great underestimate in that many suicides are masked as accidents. (3)

How does Clinical Depression affects others?

Depression is not just the problem of those who are depressed. For every depressed person, the family and friends of whom also suffer. Human suffering is only part of the destruction caused by depression. Also, it is estimated that depression costs billions of dollars in reduced and lost productivity in the workplace. (3) Clinical depression affects everyone, not only those who are ill.

WWW Sources

1) Text: Rosenzweig, Leiman, and Breedlove. 2nd Edition. Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience. Sinauer Associates, Massachusetts, 1999.

2) Dr. Ivan's Depression Central

3)Scientific American Article: "The Neurobiology of Depression"

4)A Depression Web Site

5)More Information on Depression


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