With variation in the types of depression, the symptoms of depression also vary. In fact, the diagnosis of depression is done largely on the basis of the symptoms and the types of depression. The symptoms of chemical depression include feeling sad, lonely, or depressed. With the progress of the disease, feeling depressed at any event might seem to be a normal reaction for the person. This is the symptom of major depression, when these feelings overwhelm and hamper the normal functioning of life. Depressiontreatment at such a stage is essential, because if not treated it can cause huge suffering, and can also lead the person to commit suicide. Some of the other symptoms include:

1. Difficulty in concentrating, and making decisions
2. Hopelessness feeling and a feeling of guilt
3. Sad and empty feeling
4. Restlessness accompanied by irritability
5. Suicidal thoughts

Infectious diseases or psychological problems might also lead to the development of depression. Thus, ranging from major depressive disorders, dysthymic disorder, bipolar disorder, postpartum disorder, premenstrual dysphoric disorder, seasonal affective disorder and atypical depression are the different types of depression that might occur in a person.

The risks of coronary artery disease might also increase the risk of coronary artery disease, asthma, HIV, and several other medical illnesses. Some of the other major complications of depression might include the tendency to increase many other existing medical complications

Treatment in any of these cases is essential, and proper treatment can help the person to recover.