Dysthymia is a form of depression that is less severe than major depression but usually lasts longer. Many people with this type of depression describe having been depressed as long as they can remember, or they feel they are going in and out of depression all the time. Symptoms usually begin slowly in adolescence or early adult life. Dysthymia does tend to run in families. People with dysthymia have a greater than average chance of developing major depression.