Medically reviewed by Susan Vachon, PA-C on January 10, 2022
The most common form of depression is called major depressive disorder. There are various other forms of depression (some of which are subtypes of major depression) including persistent depressive disorder (aka dysthymia), premenstrual dysphoric disorder (PMDD), postpartum depression, and seasonal affective disorder.
Major Depressive Disorder
Major depressive disorder is a serious medical condition in which patients experience a number of symptoms for at least two weeks or longer. The most common symptom among all forms of depression is a prolonged sense of sadness and despair. If you have MDD, you may also experience feelings of worthlessness or hopelessness; lose interest in things you used to enjoy; feel agitated or slowed down; have trouble concentrating or making decisions; experience changes in sleep and appetite; or have recurrent thoughts about death or suicide.
Persistent Depressive Disorder (aka Dysthymia)
Persistent Depressive Disorder (PDD) is a type of mood disorder. It means you’ve had an ongoing depressed or irritable mood for most days over a period of at least two years. Additional symptoms that can occur with PDD are changes in appetite, insomnia or excessive sleeping, low energy, poor self-esteem, difficulty with concentration, and a sense of hopelessness. These symptoms may cause distress or problems with your ability to work, study, socialize and interact with others.
Premenstrual Dysphoric Disorder (PMDD)
Premenstrual Dysphoric Disorder (PMDD) is a very severe form of premenstrual syndrome (PMS). PMDD can make it difficult to perform daily tasks. If you have PMDD, you experience symptoms like anxiety, irritability, mood swings and depression. You may also feel like ending your life or harming others. Women with PMDD usually have symptoms 7-10 days before their period begins that last an average of 6 days a month. These symptoms typically improve once menstruation begins.
Postpartum depression refers to depression symptoms that can occur post-delivery. These symptoms most commonly begin within the first month after birth but can occur anytime within the 12 months following birth. In some instances, symptoms can occur before birth. Symptoms are very similar to those experienced by women with clinical depression in general (feeling sad, stressed, anxious, irritable or agitated). The risk of postpartum depression is higher in women who have a past history of depression in their lifetime before pregnancy.
Seasonal Affective Disorder
The term seasonal affective disorder, or SAD, refers to a type of depression that is triggered by changes in seasons. SAD is associated with a particular change in daylight hours. Symptoms include feelings of sadness and hopelessness, loss of interest in activities once enjoyed and weight gain or weight loss. People with SAD typically experience these symptoms during autumn and winter months when there are less hours of sunlight each day.