When you hear the word "depression", major depressive disorder probably comes to mind — which makes sense, because it's the most common kind of depression out there, striking up to one in 10 people over the course of their lives. You might have major depressive disorder when you've had a depressed, low, empty, hopeless, pessimistic mood most of the time for at least two weeks, and you've lost interest in the kinds of activities that used to mean something to you. Other important possible symptoms include weight gain or weight loss due to appetite changes, insomnia, oversleeping, low energy and fatigue, moving more slowly or being physically restless, trouble concentrating, indecisiveness, guilt and feelings of worthlessness, and in some cases thoughts about death or suicide.
This kind of depression can strike anyone — regardless of circumstance or any particular trigger.
Adjustment disorder with depressed mood
A fairly new diagnosis, adjustment disorder is a label available to clinicians who are presented with patients who have reactions that are considered "excessive" or "abnormal" to an identifiable stressor or trigger — like the death of someone close to you, a divorce or breakup, financial catastrophe, or job loss, for instance. Possible symptoms include defiant or impulsive behavior, trembling and skipping heartbeats, but in the case of "adjustment disorder with depressed mood", we're basically talking about symptoms of depression with a cause that can be pinpointed.
To "qualify" for this diagnosis, your symptoms:
- Have to rear their head within three months after the triggering event occurred or started.
- Last less than six months after the cause of the symptoms stops being present. This bit also explains why it's called adjustment disorder; you're basically having trouble "adjusting" to a new situation in your life.
- Should be worse than "expected" in response to a situation like yours — this is clearly culture-dependent to some extent.
- Can't be explained by another disorder.
Persistent depressive disorder
Persistent depressive disorder — which used to be called dysthymic disorder and may also be referred to as dysthymia — is similar to major depressive disorder, with patients meeting its diagnostic criteria. Its duration is longer, however; at least two years. The depression is usually mild to moderate, and people who have persistent depressive disorder may have months in which they feel a lot better.
Postpartum depression — which has the same possible symptoms as major depressive disorder and is treated with antidepressants and talk therapy — can strike anytime within the first 12 months of giving birth. It is important to note that the symptoms of postpartum depression are more severe and long-lasting than another phenomenon called the "baby blues", in which new mothers feel down, weepy, and full of doubt for a short time after their baby is born. While the baby blues subside on their own, postpartum depression warrants treatment.
Psychotic depression, or major depression with psychotic features, combines the symptoms of major depressive disorder with those of psychosis. People who suffer from it may have:
- Delusions — persistent false beliefs despite ample evidence to that they're not true (the convinction that people are "out to get you", for instance).
- Hallucinations — seeing, feeling, or hearing things that aren't there.
Seasonal affective disorder
Seasonal affective disorder, the acronym for which is, aptly, SAD, is a seasonal kind of depression. It usually strikes during the winter, and is linked to a lack of exposure to sunlight — which is why it's more common in people who live far from the equator, in places where it is dark much or all of the time in winter. Occasionally people are, however, affected by SAD during summer rather than winter.
Now for a 'bonus' — other disorders that present with depressive symptoms
Bipolar disorder used to be called "manic depression" — because this serious mood disorder combines manic periods that may include a state of euphoria, a feeling of invincibility, delusions of grandeur, and sometimes psychosis, with "hypomanic" periods during which patients meet the diagnostic criteria for major depressive disorder. It isn't depression, though, but a whole different mood disorder.
Unspecified depressive disorder may be diagnosed in people who have symptoms of major depression and whose functioning is significantly impaired, but who do not meet the diagnostic criteria for major depressive disorder, nor any other kind of depression.
Premenstrual dysphoric disorder is a severe form of premenstrual disorder (PMS) in which patients meet the diagnostic criteria for major depression, enough to be severely depressed, before their periods. Many sufferers also have seasonal affective disorder and anxiety, while some also have a seperate diagnosis of major depression. Besides antidepressants and talk therapy, hormonal birth control and ovulation-suppressing medications are among the main treatments that seem to help.
Post-traumatic stress disorder isn't depression — but people with PTSD may have some of the same symptoms. It is possible to suffer from PTSD and major depression at the same time, as well.