Depressive disorders are mood disorders that come in different forms, just as do other illnesses, such as heart disease and diabetes. Three of the most common types of depressive disorders are discussed below. However, remember that within each of these types, there are variations in the number, timing, severity, and persistence of symptoms. There are also differences in how individuals experience depression based on age.
Major depression

Major depression is characterized by a combination of symptoms that last for at least two weeks in a row, including sad and/or irritable mood (see symptom list), that interfere with the ability to work, sleep, eat, and enjoy once-pleasurable activities. Difficulties in sleeping or eating can take the form of excessive or insufficient of either behavior. Disabling episodes of depression can occur once, twice, or several times in a lifetime.

Dysthymia

Dysthymia is a less severe but usually more long-lasting type of depression compared to major depression. It involves long-term (chronic) symptoms that do not disable but yet prevent the affected person from functioning at "full steam" or from feeling good. Sometimes, people with dysthymia also experience episodes of major depression. This combination of the two types of depression is referred to as double-depression.

Bipolar disorder (manic depression)

Another type of depression is bipolar disorder, which encompasses a group of mood disorders that were formerly called manic-depressive illness or manic depression. These conditions show a particular pattern of inheritance. Not nearly as common as the other types of depressive disorders, bipolar disorders involve cycles of mood that include at least one episode of mania or hypomania and may include episodes of depression as well. Bipolar disorders are often chronic and recurring. Sometimes, the mood switches are dramatic and rapid, but most often they are gradual.

When in the depressed cycle, the person can experience any or all of the symptoms of a depressive disorder. When in the manic cycle, any or all of the symptoms listed later in this article under mania may be experienced. Mania often affects thinking, judgment, and social behavior in ways that cause serious problems and embarrassment. For example, indiscriminate or otherwise unsafe sexual practices or unwise business or financial decisions may be made when an individual is in a manic phase.

A significant variant of the bipolar disorders is designated as bipolar II disorder. (The usual form of bipolar disorder is referred to as bipolar I disorder.) Bipolar II disorder is a syndrome in which the affected person has repeated depressive episodes punctuated by what is called hypomania (mini-highs). These euphoric states in bipolar II do not fully meet the criteria for the complete manic episodes that occur in bipolar I.

Symptoms of depression and mania

Not everyone who is depressed or manic experiences every symptom. Some people experience a few symptoms and some many symptoms. The severity of symptoms also varies with individuals. Less severe symptoms that precede the more debilitating symptoms are called warning signs.

Depression symptoms of major depression or manic depression
Persistently sad, anxious, angry, irritable, or "empty" mood


Feelings of hopelessness or pessimism


Feelings of worthlessness, helplessness, or excessive guilt


Loss of interest or pleasure in hobbies and activities that were once enjoyed, including sex


Social isolation, meaning the sufferer avoids interactions with family or friends

Insomnia, early-morning awakening, or oversleeping


Decreased appetite and/or weight loss, or overeating and/or weight gain


Fatigue, decreased energy, being "slowed down"


Crying spells


Thoughts of death or suicide, suicide attempts


Restlessness, irritability


Difficulty concentrating, remembering, or making decisions


Persistent physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and/or chronic pain

Mania symptoms of manic depression
Inappropriate elation


Inappropriate irritability or anger


Severe insomnia or decreased need to sleep


Grandiose notions, like having special powers or importance


Increased talking speed and/or volume


Disconnected thoughts or speech


Racing thoughts


Severely increased sexual desire and/or activity


Markedly increased energy


Poor judgment


Inappropriate social behavior