Depression presents in many different ways and can cause a wide variety of physical, psychological and social symptoms. Doctors describe depression in the following three ways:
Severity
Depression can be described as mild, in which there is some impairment of daily life, or moderate, in which there is significant impairment in daily life, or severe, in which case activities of daily life are virtually impossible.
Presence or Absence of Physical Symptoms
Most patients with depression have one or two physical (or 'biological' or 'somatic') symptoms. However, some have several.
Presence or Absence of Psychotic Symptoms
Most people with depression do not have psychotic symptoms such as hallucinations or delusions. However, some do.