All these factors can affect the functioning of the brain.  It is known that certain parts of the brain control mood and if these areas become dysfunctional, depression results.  It is also known that certain chemicals found in the brain act as messengers between the nerve cells.  There are many such messengers.  Some of these messengers become deficient in some way and this results in depression.  One of the messengers most important in depression is a substance called serotonin, although others such as noradrenaline and dopamine are important as well  Pharmacological treatments for depression affect these essential messenger systems.

Studies using special x-rays of the brain have demonstrated that persons who are depressed have decreased metabolic activity in important parts of the brain that control mood.  Of note, this dysfunction is reversed with effective treatment.

It is important to note what does not cause depression:

   * depression is not caused by bad parenting
   * depression is not self-inflicted and, therefore, a person with depression
         cannot "snap out of it" or just "pull up their socks"
   * depression is not due to a "weakness" in personality or character
   * depression is not a sinful disease, not a form of punishment

Depression is a serious illness that has many possible causes; with the end result being a biological illness that affects the functioning of the part of the brain controlling mood.  It is due to abnormalities in the chemical messenger systems in the brain.  Depression is very much like the illness diabetes.  Diabetes also has several causes, but it is known that the end result is a deficiency in insulin production.  Both diabetes and depression are easily treated by correcting the chemical deficiency but other factors such as lifestyle changes are also important.

Are there any tests for depression?

Depression is a diagnosis made primarily on signs and symptoms.  A physician must rule out any other physical illness that can cause depression.  This may involve blood tests, x-rays and a physical examination.

There are some tests that can help to confirm the diagnosis of depression, but they are not usually necessary and not routinely done.  One such test is called the dexamethasone suppression test.  There are a number of psychological tests, which have rating scales that help to assess the severity of depression.

Can depression be treated?

Depression can be very successfully treated and further episodes can be prevented.  The treatment of depression involves a combination of several psychological and biological approaches.