Which disorder is characterized by persistent feelings of sadness and lack of interest?

The disorder characterized by persistent feelings of sadness and lack of interest is Major Depressive Disorder. This condition involves a pervasive low mood that lasts for at least two weeks and includes symptoms such as diminished interest or pleasure in almost all activities, significant weight change, sleep disturbances, fatigue, feelings of worthlessness, and difficulty concentrating. These symptoms must be severe enough to interfere with daily functioning.

In contrast, Generalized Anxiety Disorder involves excessive worry about various aspects of life without the predominant symptoms of sadness and lack of interest that define depression. Bipolar Disorder includes mood swings that encompass periods of high energy (mania or hypomania) and depression, making it distinct from the consistent low mood seen in Major Depressive Disorder. Obsessive-Compulsive Disorder primarily entails unwanted thoughts (obsessions) and repetitive behaviors (compulsions) rather than the emotional symptoms central to depression. Thus, when identifying a disorder that specifically manifests as persistent sadness and a lack of interest, Major Depressive Disorder is the clear choice.