*Common symptoms of depression include persistent low mood, loss of interest and enjoyment, changes in sleep and appetite, thoughts of guilt, difficulty concentrating, and decreased energy. *

Symptoms in people with depression vary from person to person. The severity, frequency, and duration of symptoms vary between individuals and their specific disease. Signs and symptoms include: Persistent sadness, anxiety, or a feeling of "emptiness." - Persistent sadness, anxiety, or "empty" feelings - feeling hopeless or pessimistic - Feeling guilty, worthless, or helpless - Sensitivity, irritability, restlessness - Loss of interest in activities or hobbies that you once enjoyed (including sex) - Fatigue and lack of energy - Difficulty concentrating, remembering details, and making decisions - Insomnia, early awakening or excessive sleepiness - Overeating or loss of appetite - Suicidal thoughts, suicide attempts - Aches or pains, headaches, cramps, or digestive problems that don't go away with treatment. Major depressive disorder is characterized by the presence of at least five symptoms, which can be classified from mild to severe. Severe episodes can be accompanied by psychotic symptoms such as paranoia, hallucinations, or incapacity.

Subthreshold (mild) depression is characterized by the presence of 2 to 4 depressive symptoms, including depressed mood or anhedonia, lasting more than 2 weeks.

Persistent depressive disorder (dysthymic disorder) is characterized by three or four dysthymic symptoms present on most days for at least 2 years. Symptoms of dysthymia include depressed mood, appetite changes, sleep disturbances, decreased energy, low self-esteem, difficulty concentrating, and feelings of hopelessness.