DepressionLike a heart problem, a stomach ulcer or any other medical illness, depression is also just like any other medical condition. The symptoms for clinical depression are usually similar but may change among individuals. Some of the symptoms may consist of the following: always feeling sad or 'empty', feeling hopeless, helpless, guilty or unworthy. Other things such as: substance abuse, constant fatigue, less of interest in usual activities, decrease in sexual desire, changes in sleep and appetite habits, anger, consistent crying, anxiety, fear, decrease in concentration, forgetfulness, difficulty making decisions, suicidal thoughts, suicidal plans or suicide attempts and long-term physical pain that does not change with any therapy may be other symptoms as well.