Depression often leads to poor quality of life and impaired functioning.<unk>  is defined as loss of interest (anhedonia) and/or depressed mood for two or more weeks with at least 4 of the following features: sleep disturbances, loss of appetite/increased appetite, feeling guilty/worthless, loss of energy, loss of concentration, psychomotor retardation, or suicidal ideation.The pathophysiology of depression is not completely understood, but it is thought that decreased  levels of  monoaminergic neurotransmitters Dopamine, Serotonin and Nor-epinephrine are responsible for depressed mood. When a patient with depressed mood comes to primary care, a detailed psychiatric interview is important to evaluate the psychiatric symptoms and assess the effect of symptoms on functioning of the patient. A physician is required to foster a positive rapport with the patient and help with sensitive matters. If needed, family and friends of the patient may be involved and cultural, social, and situational factors should be considered to diagnose triggering factors.
Clinical depression
Depression 
Post travel depression
Atypical depression
Post stroke depression
Suicide ideation
Melancholic depression
Psychotic depression