We all feel sad sometimes, but depression goes way beyond ordinary sadness. Depression is a mood disorder—a type of mental illness that mainly affects your mood. Everyone experiences depression a little differently, but there are a few specific types of depression. Usually people just refer to all of these as “depression,” but understanding the differences can help you make sense of your own experiences.
Major depressive disorder (MDD)
People with major depressive disorder (or “major depression”) experience symptoms of depression almost all day, nearly every day. An episode of major depression lasts at least 2 weeks—but it often lasts up to six months, and can sometime last for several years.
About half of people who experience one episode of major depression will experience at least one more episode later in life. Many of those people will experience multiple episodes of depression throughout their lives, especially if it goes untreated.
Psychotic depression isn’t a separate type of depression, but people experiencing a really severe depressive episode can sometimes have psychotic symptoms.
Persistent depressive disorder (PDD)
Persistent depressive disorder is less severe than major depression, but it lasts longer. People with persistent depressive disorder experience symptoms of depression most days for at least two years, but don’t experience a major depressive episode during that time. If you have persistent depressive disorder, you may have been depressed for so long that you have a hard time even remembering what it’s like to not be depressed!
Persistent depressive disorder used to be called dysthymia, and you can still find a lot of information about it online by searching for “dysthymia.”
Many people experience depression after giving birth. Post-partum depression lasts anywhere from two weeks up to a year. It can be really distressing, because people expect to feel happy when they are welcoming a new baby into their lives. But post-partum depression is normal and common. It’s also common to experience depression during pregnancy.
Pre-menstrual dysphoric disorder (PMDD)
This is an extreme form of pre-menstrual syndrome (PMS). People who experience pre-menstrual dysphoric disorder experience severe symptoms of depression in the week leading up to their period.
Seasonal affective disorder (SAD)
Many people’s moods are affected by the seasons. When people experience more symptoms of depression during one part of the year, this is called seasonal affective disorder. Most people who have seasonal affective disorder get depressed in the winter, but a few people actually get more depressed in the summer.
Depression and bipolar disorder
People with bipolar disorder experience alternating episodes of depression and mania. Mania is an extended period of extreme high energy and positive mood. Bipolar disorder is different from being “moody.”
- American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: Author.
- American Psychiatric Association. What is Depression? Retrieved from https://www.psychiatry.org/patients-families/depression/what-is-depression