Some people are misguided in thinking that depression is merely a state of mind that people can "snap out of" if they are willing. This is not true. Depression is a real illness, just like heart disease or diabetes. And, as people deal with any chronic disease, they must learn how to recognize depression and control it throughout their lives.

You should not feel embarrassed or ashamed if you feel depressed. You should, however, let your doctor know how you are feeling. If physicians are not aware of all of the symptoms, it is difficult for them to make a diagnosis. There are many effective ways to treat depression and prevent it from interfering with the quality of life. If depression goes untreated, it can turn into a life-threatening disease.

Depression is an illness that causes a disturbance in an individual's emotions and feelings, what is referred to as mood. Most people experience a down mood from time to time throughout their lives. True depression is suspected when people consistently find themselves in depressed moods every day over a period of two weeks or more. Typically, if people are suffering from depression, their mood will prevent them from living their lives as they normally do. Stressful life events, like a death in the family or financial problems, can trigger depression. Sometimes, people find themselves depressed for no apparent reason.

Most often, depression produces a sad mood. However, some people experience indifference, apathy, loss of pleasure or irritability instead. In addition to disturbing one's mood, depression can interfere with several basic body functions including changes in sleep, decreased or increased appetite, sluggishness, restlessness, fatigue, loss of concentration and poor memory. People with depression may feel excessive shame or guilt and dwell on thoughts of death or dying, including ideas about suicide.

Depression Throughout History

Even in ancient times depression was recognized as an illness. The Ebers Papyrus, one of the world's oldest medical documents from ancient Egypt, describes a condition of severe despondency that is equivalent to our modern definition of depression. There are references to depression in the book of Samuel of the Old Testament. Hippocratic writings of the fourth century describe "melancholy" as a condition thought to arise from an imbalance in the humors of the body. And, in addition to many references to depression in literature, many notable philosophers, scientists, politicians, actors and writers have struggled with periods of depression in their lives.

Who Gets This Disease?

At any given time, about 5 percent of the population of the United States suffer from major depression. It affects people of all ages, races and ethnic groups. For unknown reasons, women are almost twice as likely as men to suffer from depression. The lifetime prevalence of major depression is about 20 to 26 percent for women and 8 to 12 percent for men. Manic depressive illness is less common. Between 0.5 and 1 percent of the population suffer from this type of depression.

Unlike other diseases that an individual can contract only once in a lifetime, depression is a recurrent condition. Those who have had an episode of depression have better than a 50 percent chance of the depression recurring sometime in their lives. Depression can occur at any age, but the average age of onset is about 40. Although many people experience their first episode of depression in their late teens or early adulthood, the incidence of depression increases with age. The elderly are at a high risk of developing depression as they face multiple health problems or the loss of loved ones. Persons of any age or race may contemplate suicide as part of their depression, but older white men are more likely than younger individuals to actually commit suicide. Overall, about 15 percent of patients who have depression for more than one month commit suicide. Many of these patients seek medical help before their suicide, often within one month of their death.

Understand Your Body

The brain is the control center for every part of the body. It controls our conscious behavior (walking and thinking) and our involuntary behavior (heartbeat and breathing). The brain also regulates our emotions, memory, self-awareness and thought processes. The brain receives information via nerve cells, called neurons, from every part of the body. The brain evaluates the information it receives and sends appropriate instructions via the neurons. Each one communicates with the cells around it through electrical signals. When a nerve signal reaches the end of one cell, it must pass over a gap to reach the other one. The nerve causes a release of chemicals called neurotransmitters. The improper relay of signals may be partly responsible for depression.

What Causes Depression?

• Biological Factors --The underlying causes of depression are not well understood, although there are a lot of clues suggesting that various systems in the brain may cause depression or be affected by it. For example, major depression is characterized by excessive sleep. So, it is very likely that the brain stem (which controls sleep) plays a role in depression. Similarly, abnormalities in the cerebral cortex (which controls thinking) probably have to do with the inability to concentrate and negative thoughts that can be characteristic of depression.

Imbalances in neurotransmitters (chemicals in the nervous system) seem to play a key role in depression. Research into the way antidepressant medications function has provided the greatest insight in this area. For example, certain medications used to treat depression have been shown to increase the amount of neurotransmitters such as norepinephrine, serotonin and dopamine in the brain; this suggests that a chemical imbalance in the brain causes depressive symptoms. Abnormalities in the neuroendocrine system of the brain also seem to play a role in depression, including abnormalities linked to the thyroid, pituitary and adrenal glands.

• Genetic Factors -- Individuals with a family history of depression have a greater risk of becoming depressed than the general population. Some researchers believe that a "single depression gene" exists, but there is mounting evidence to suggest that several genes may be responsible for causing depression.
• Social and Environmental Factors -- Social and environmental factors also may cause depression, but there are many conflicting studies concerning this issue. For example, some studies suggest that adverse life events such as divorce, serious illness or multiple episodes of misfortune may cause depression. Other studies have found that no such relationship exists.

• Strokes and Depression --In some cases, a stroke may cause depression. Strokes that cause depression are more likely to occur in the left frontal lobe of the brain, but they can be found elsewhere. One study of older adults found that damage to specific areas of the brain (subcortical white matter lesions) were more likely to be found in people with major depression than in healthy individuals, or patients with dementia (progressive decline in the ability to think and reason). These smmall, subcortical strokes are the type found in individuals with long-standing high blood pressure (hypertension), diabetes or other medical illnesses that affect blood vessels in the brain, heart and other organs.

Will I Get Better?

The course and outcome of depression varies with each individual. Depression may begin suddenly or build up gradually. It may last a few weeks, months or even years. Most depressive episodes clear spontaneously after six months.

Effective treatment can bring depression under control in a matter of weeks. However, 20 percent of patients become chronically depressed. With antidepressant therapy, the overall prognosis is positive; however, more than 50 percent of patients will have a recurrence of depression at some point in their lives.

The Risk of Suicide

The most serious complication of depression is suicide. About 15 percent of patients with untreated depression will kill themselves. It is extremely important for people to seek treatment immediately if they are feeling depressed or if they know someone who is thinking and speaking a great deal about death and suicide. People suffering from depression may feel suicide is a deserved punishment or that the world would be a better place without their existence. In some cases, depressed patients may think about harming others. Other Complications from Depression Aside from suicide, depression can have serious consequences resulting in poor performance at work or school, disruptive relationships, substance abuse and unnecessary medical testing. There is some concern that depression may have a negative affect on the immune system, making people more susceptible to other medical illnesses. However, this relationship never has been proven.

National Institute of Mental Health
Reprinted with permission.