Depression is an illness that can interfere with a person’s thoughts, feelings, behavior, and physical health. Everyone feels sad, “blue”, or “down-in-the-dumps” at times. Depression is different. It can last for weeks, months, or years and greatly interfere with a person’s life. It is the leading cause of disability in the U.S. from medical illness. If not treated, depression can lead to suicide. The good news is that most people can be successfully treated.

You might have a condition known as major depression if you have several of the following symptoms at the same time, these symptoms are different from the way you usually feel, they last longer than two weeks, and they are interfering with your life. Some people have few symptoms; others have many. Symptoms might be worse for some people than others, but also the severity can change over time for each person.

• sad or irritable mood
• major changes in sleep, appetite, and energy
• difficulty thinking, concentrating, and remembering
• physical slowing or restlessness
• lack of interest in or pleasure from activities that were once enjoyed
• feelings of guilt, worthlessness, hopelessness, and emptiness
• recurrent thoughts of death or suicide
• physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and pain.

There are different types of depression just like there are different types of other illnesses. Three of the most common include:

• Major depression, which involves a combination of different symptoms that interfere with a person’s daily life and last a long time. Someone may be diagnosed with mild, moderate, or severe major depression.
• Dysthymia, which is a less serious form of depression. The symptoms are not disabling but also last a long time and can keep a person from functioning well and/or from feeling well.
• Bipolar disorder, which is also called manic-depressive illness. It is not as common as the other forms of depression. In this disorder, a person’s mood can shift from depressed to manic. In the manic cycle, the person might be extremely active, sleep little, talk too much and too fast, and do things that can cause problems such as spending too much money.

How is depression diagnosed?

Depression can be diagnosed by a primary care or mental health practitioner such as a psychologist or clinical social worker. It is a good idea to see your primary care practitioner early on. Some medical conditions and medications can cause the same symptoms as depression. Through a physical exam, patient interview, and diagnostic tests, the primary care practitioner can determine if something other than depression might be causing the symptoms.