A mood disorder represents a category of mental illnesses in which the underlying problem primarily affects a person’s persistent emotional state (their mood).
Depression: This mood disorder causes a persistent feeling of sadness and loss of interest in daily activities. Also called major depressive disorder or clinical depression, it affects how one feels, thinks, and behaves. Untreated it can lead to a variety of emotional and physical problems.
Bipolar Disorder: This mood disorder (formerly called manic-depressive illness or manic depression) causes unusual shifts in mood, energy, activity levels, concentration, and the ability to carry out day-to-day tasks. Moods can range from periods of extremely “up,” elated, irritable, or energized behavior (known as manic episodes) to very “down,” sad, indifferent, or hopeless periods (known as depressive episodes).
Bipolar disorder is typically diagnosed during late adolescence (teen years) or early adulthood. Occasionally, bipolar symptoms can appear in children.