Depression causes changes in thinking, feeling, behavior, and physical well-being. Changes in Thinking - You may experience difficulty with concentration and decision making. Some people report problems with short term memory. Negative thoughts and thinking are characteristic of depression. Some people have self-destructive thoughts during a more serious depression.
Many people report feeling sad for no reason.
Others report that they no longer enjoy activities that they once found pleasureable. You might lack motivation, becoming more apathetic. Sometimes irritability is a problem, and you may have more difficulty controlling your temper. In the extreme, clinical depression is characterized by feelings of helplessness and hopelessness. Changes in Behavior - The changes in behavior common during depression are reflective of the negative emotions you experience.