Positron Emission Tomography (PET)

Positron emission tomography is a computerized radiographic technique used to examine the metabolic activity in various tissues, especially those in the brain.

Depressed patients who underwent PET showed unusual activity in the limbus and the cortex of the brain. Also increased activity in the amygdale (a part of the limbic system which plays an important part in motivation and emotional behavior) of the left hemisphere is an indication of future depression.

Some of these methods are still in experimental stage and more researches are on to find a conclusive test for depression.