Questions: What is dysthymia or persistent depressive disorder?
Answers: Dysthymia, now called persistent depressive disorder or PDD, is a mood disorder. It is related depression (major depressive disorder). The difference between the two is in the number of symptoms and the amount of time that they last. Someone diagnosed with PDD would experience two to four of the symptoms below for at least two years with no periods of wellness during that time, while someone diagnosed with major depressive disorder would experience five or more of the symptoms below for at least two weeks. 
   Symptoms of PDD include: 
   There is a myth that PDD is not as severe an illness as major depressive disorder, but research shows that the disability of the illness, like the ability to work productively and enjoy hobbies, may be as severe in PDD as it is in major depressive disorder. As PDD involves a smaller number of symptoms that last for a very long time, many people begin to assume PDD is just part of their personality rather than an illness that can be effectively treated. So you should most certainly talk to a doctor or mental health professional if you think you might have PDD.