Mental illnesses are more common than you may thing. According to the National Institutes of Health, about one in four American adults suffers from some type of mental disorder. In fact, these mental health problems are the country's leading cause of disability.
Depression is not the most common mental disorder—that would be anxiety—but it is the leading cause of disability. It is a mood disorder that can cause extreme and persistent feelings of sadness, hopelessness, and worthlessness. Depression can affect someone so severely that their relationships, career, and personal life may deteriorate. Luckily, it is also a treatable medical condition, and many with depression can live very normal and even happy lives.