Final answer:
Persistent depressive disorder, also known as dysthymia, is characterized by mild to moderate depressive symptoms that last for at least two years.
Step-by-step explanation:
Persistent depressive disorder, also known as dysthymia, is characterized by mild to moderate depressive symptoms. Unlike major depressive disorder, which involves severe and episodic depressive episodes, dysthymia is a chronic condition that lasts for at least two years. Symptoms of dysthymia may include feelings of sadness, hopelessness, low energy, trouble sleeping, poor concentration, and changes in appetite.