Depression is a sad or discontented mood that can leave a person feeling lethargic, unmotivated, or hopeless. In some cases, depression can lead to suicidal ideation. Depression may occur in a severe form, as in major depression, or in a more chronic, mild-to-moderate form, as is the case with persistent depressive disorder.

Depression’s symptoms can vary greatly from person to person and may even change throughout the course of the illness. Symptoms may also vary depending on an individual’s gender, culture, or age. Adolescents experiencing depression might appear irritable and agitated, and women may be more likely to admit to depression than men, while certain cultural groups might mask their feelings or display them differently.