Depression isn’t just a case of the blues where you feel down for a while. Most people go through periods of feeling down, but when you’re depressed you feel persistently sad for weeks or months, rather than just a few days. Depression affects people in different ways and can cause a wide range of symptoms from lasting feelings of unhappiness and hopelessness, to losing interest in the things you used to enjoy. Symptoms of depression can occur along a spectrum both in duration and severity. This test is often used in a primary care setting to assess the likelihood of depression and how severe it might be. The screening has nine questions, and those questions ask how often you have been bothered by a series of nine problems during the last two weeks. The questions address sleep, energy, appetite, and other symptoms of depression, as well as the frequency of these symptoms.
Kroenke K, Spitzer RL, Williams JB; The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001 Sep 16(9):606-13.
