Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. Also called major depressive disorder or clinical depression, it affects how you feel, think and behave and can lead to a variety of emotional and physical problems. You may have trouble doing normal day-to-day activities, and sometimes you may feel as if life isn't worth living.
A panic attack is the abrupt onset of intense fear or discomfort that reaches a peak within minutes and includes at least four of the following symptoms: Palpitations, pounding heart, or accelerated heart rate. Sweating. Trembling or shaking. Sensations of shortness of breath or smothering.
PTSD is a condition of persistent mental and emotional stress occurring as a result of injury or severe psychological shock, typically involving disturbance of sleep and constant vivid recall of the experience, with dulled responses to others and to the outside world.
Social anxiety is the fear of social situations that involve interaction with other people. You could say social anxiety is the fear and anxiety of being negatively judged and evaluated by other people. It is a pervasive disorder and causes anxiety and fear in most all areas of a person's life.
If you have a mood disorder, your general emotional state or mood is distorted or inconsistent with your circumstances and interferes with your ability to function. You may be extremely sad, empty or irritable (depressed), or you may have periods of depression alternating with being excessively happy (mania).