Women suffer from unipolar (as opposed to bipolar or manic) depression in greater numbers than men do; twice as much by most estimates. Three times as many teenage girls as boys report having experienced an episode of major depression.
The reason or reasons why women have unipolar depression more frequently than men is less definite, due to a great extent to the fact that we don’t fully understand what causes depression, whether in men or women. Depression is a highly individual disease. Each case is different. One person’s depression may be wholly chemical, while someone else’s is brought on by events and stressful factors in her life. Yet another person may suffer depression due to a combination of chemical and environmental factors.