One of the main symptoms of major depressive disorder is a distorted, negative view that makes it impossible to believe that things or situations in a person's life can resolve in a positive way, according to Healthline. Additional symptoms include social isolation, lack of energy, irritability, loss of interest in once pleasurable activities and suicidal behavior. In severe cases, a patient could experience hallucinations or delusions.
Major depressive disorder is a serious mood disorder that interrupts a person's ability to function in everyday life, states Healthline. People who experience this condition often report that sadness, loss, frustration and anger interfere with their lives for weeks or months at a time. As of 2015, the exact cause of the condition is unknown. However, research suggests that the condition results from chemical changes in a person's brain, a genetic disposition or a combination of both factors. It can also be triggered by stressful events, such as loss, social isolation, or the death or illness of a loved one.
Treating major depressive disorder usually involves medicine, talk therapy or a combination of both, states Healthline. Commonly used antidepressants include Celexa, Prozac and Zoloft. Talk therapy involves helping a patient develop ways of coping with her depression. Treatment could include cognitive behavioral therapy to help the patient deal with negative thoughts, or it could include psychotherapy to help a person better understand the issues behind negative feelings and thoughts.