Major Depressive Disorder

Depressed mood for most of the day, nearly every day for 2 weeks or longer
Loss of interest or pleasure in activities the person usually enjoys
Other syptoms can include those listed on the symptoms page

Psychotic Depression

Most common in late life
Major depressive disorder accompained by delusions (believing things that are not true) or hallucinations (seeing or hearing things that do not exist)

Minor Depressive Disorder

Symptoms do not meet the criteria for major depressive disorder

Dysthymic Disorder

Fewer or less symptoms than major depressive disorder that last longer than major depressive disorder