More than feeling sad, clinical depression is a common, real and treatable illness. As a matter of fact, it is one of the most common mental illnesses, affecting more than 19 million Americans each year. This includes major depressive disorder, manic depression and dysthymia, a milder, longer-lasting form of depression.

This mental affliction causes people to lose pleasure from daily life, can complicate other medical conditions, and can even be serious enough to lead to suicide. Depression can occur to anyone, at any age, and to people of any race or ethnic group.  Depression is never a "normal" part of life, no matter what your age, gender or health situation.

Unfortunately, though treatment for depression is almost always successful, fewer than half of those suffering from this illness seek treatment. Too many people resist treatment because they believe depression isn't serious, that they can treat it themselves or that it is a personal weakness rather than a serious medical illness.

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Link: http://www.mentalhealthamerica.net/go/information/get-info/depression/depression-what-you-need-to-know/depression-what-you-need-to-know