About 7% of the US population is suffering from depression that needs medical attention. The number of people who have suffered at one time or another in their life from depression is about three times as high. According to the World Health Organization women are two to three times as likely to develop a depression than are men.

Medical scientists believe that the tendency for depression is at least in part caused by hereditary factors. People who have gone through a bout of depression once have a higher risk of falling ill again.

Depression can me treated successfully with a combination of drugs and psychotherapy.

Doctors suspect that certain neurotransmitters (chemical agents that carry nerve signals) like serotonin and noradrenalin aren't working as efficiently in a sick person as in a healthy person. The reasons for this deficiency aren't known, but it is believed than genes and hereditary factors play an important role. Drugs that combat depression do it by 'helping' serotonin and noradrenalin to do their job more effectively in the brain.

It is usually, but not always, very difficult and painful events in a person's life that trigger depressive episodes. With the use of psychotherapy the doctor tries to help the patient to work through those events or help him or her to avoid them altogether.

Types of Depressions

1. Unipolar Depression. This is the most common form of depression. It's called unipolar because the patient is 'only' depressed, but not manic-depressive. Main symptoms are feeling very low in the morning, waking up very early, insomniac tendencies and feeling depressed.

2. Bipolar Affective Depression. As opposed to the unipolar depression the bipolar depression is marked by depressive and maniacal phases. Patients suffering from it are delusional about their own capacities and may, for example, work day and nights for weeks on end without feeling exhausted.

3. Winter Depression. It's also called the seasonal depression, since it occurs usually at the onset of autumn or winter and disappears with the coming of spring. This form of depression therefore only lasts up to 5 or 6 months. The most common symptom is the lack of physical energy, not the feeling of being depressed per se.

4. Some prescription drugs may cause depression, like those with a high element of cortisone, contraceptive products like the pill and drugs combating heart disease (beta blockers).

It's natural to feel low sometimes, but it is different from a depression. In most cases it is easy to distinguish between simple mood changes, even if they come in rapid succession and a disease like depression.

There is not always an outside event that triggers the onset of a depression. That's why it is so difficult to understand not only for the patient but for his or her relatives as well. They definitely suffer through and with the sick person. Since there is no apparent identifiable catastrophe that can explain the mood swings of the patient, he or she very often stretches the patience of those around him or her to the limit.

The most common symptoms are: feeling generally very low, a pronounced lack of interest in normal activities like sports or socializing, loss of appetite and loss of weight (in some cases increased appetite and weight gain), the inability to sleep well (insomnia), loss of concentration, indecisiveness, diminished sexual desire, general exhaustion and lack of energy, obsessive thinking about death, suicidal tendencies and suicide attempts.