Persistent Depressive Disorder (PDD), also known as dysthymia, is a chronic form of depression that lasts for at least two years. Individuals with PDD experience prolonged periods of low mood, fatigue, and difficulty enjoying life. Though less severe than Major Depressive Disorder, PDD can significantly impair daily functioning. Treatment typically involves antidepressants and psychotherapy, such as CBT, to manage symptoms and improve quality of life.