Major Depressive Disorder (MDD): Is a common and serious medical illness that negatively affects how you feel, the way you think and how you act. Fortunately, it is also treatable. Depression causes feelings of sadness and/or a loss of interest in activities you once enjoyed. It can lead to a variety of emotional and physical problems and can decrease your ability to function at work and at home.
Depression symptoms can vary from mild to severe and can include:
- Feeling sad or having a depressed mood.
- Loss of interest or pleasure in activities once enjoyed.
- Changes in appetite — weight loss or gain unrelated to dieting.
- Trouble sleeping or sleeping too much.
- Loss of energy or increased fatigue.
- Increase in purposeless physical activity (e.g., inability to sit still, pacing, handwringing) or slowed movements or speech (these actions must be severe enough to be observable by others).
- Feeling worthless or guilty.
- Difficulty thinking, concentrating or making decisions.
- Thoughts of death or suicide.
- Symptoms must last at least two weeks and must represent a change in your previous level of functioning for a diagnosis of depression.