Depression is a mental health illness that affects one in 10 Americans.More than just feeling down, clinical depression is a mood disorder characterized by persistent feelings of sadness, hopelessness, and worthlessness that don’t go away on their own. It is essential to recognize that feeling down on occasion is a normal – and important – part of life. Sad and distressful events occur in everyone’s life, and responding to them emotionally is healthy. However, feeling miserable consistently and without any sense of hope is not normal, and should be treated as a serious medical condition.
People experience depression in different ways. It can often interfere with a person’s daily responsibilities and relationships. Left untreated, the condition may last for months or years and often becomes worse. However, depression is a treatable medical condition, and those who seek treatment often see improvements in their symptoms.
Classified as a mood disorder, depression affects people very differently. There are also different types of depression. The type of depression a person has will largely determine what kind of medical treatment the person should receive. According to the Diagnostic and Statistical Manual of Mental Disorders, there are two main categories of depression – major depressive disorder and dysthymia – and a grouping of other, less common types. There are also a number of other mood disorders that can cause depression symptoms.
People with major depression experience a near-constant state of sadness, emptiness, and despair for at least two weeks. They are unable to enjoy activities that they once found pleasurable and may have a hard time eating, sleeping, working, or connecting with others. Major depressive disorder is a debilitating disease that can seriously affect a person's health, wellbeing, and life. Untreated, episodes of major depression last an average of six months, though with 20 percent of sufferers, it could be as long as two years. People who experience major depression have a 50 percent chance of recurrence.
Although many people use the word "depression" to describe this mood disorder, medical professionals prefer to use the term "major depressive disorder" or "major depression," both of which are more clinically precise, describing a specific medical condition, as opposed to a general group of behaviors. Major depressive disorder is also typically what is meant by "clinical depression."
In some cases, major depressive disorder is accompanied by certain behaviors or caused by specific factors that make the symptoms and eventual course of the disorder significantly different than usual. Medical professionals break these special cases out into five "subtypes" of major depressive disorder:
Whereas people with major depression are uniformly depressed, people with atypical depression have what’s called mood reactivity. That is, they experience temporary emotional highs from good news and lows from bad news. Some mental health experts believe that atypical depression may in fact be a milder form of bipolar disorder known as cyclothymia. Atypical depression often first surfaces in a person’s teenage years, and can continue into adult life.
Postpartum depression is moderate to severe depression that can occur in women after childbirth. It is different than the normal “baby blues,” which can occur due to fluctuating hormones. Symptoms may include trouble eating or sleeping as well as feelings of worthlessness, restlessness, or even paranoia. They may appear soon after giving birth and up to a year later.
Seasonal Affective Disorder
People with Seasonal Affective Disorder (SAD) experience depression every year in the late fall or early winter due to limited sunlight from the change in seasons. Symptoms — which include sadness, social withdrawal, anxiety, hopelessness, and fatigue — can get worse as winter progresses.
People who suffer from melancholic depression generally experience severe anhedonia (an inability to find pleasure in positive things), significant weight loss, psychomotor agitation, and guilt. They also tend to suffer from insomnia, waking earlier in the morning than they would like.
This is perhaps the rarest subtype of major depression. Catatonic depressives suffer from severe psychomotor disturbances, either involving a sudden inability to move at all, or conversely, an excessive amount of movement that seems to have no purpose.
Although it typically has fewer or milder symptoms than major depression, dysthymia is just as serious because it lasts longer. The condition is characterized by experiencing a depressed mood most of the time for at least two years, along with at least two of these symptoms low self-esteem, hopelessness, poor concentration, poor appetite or overeating, insomnia or excessive sleep, indecisiveness, or a lack of energy.
In some cases, patients may have a disorder that is characterized by depressive symptoms but does not fit into the category of major depression, dysthymia, or another mood disorder. Some examples of depressive disorder not otherwise specified include:
Minor Depressive Disorder
Sometimes also referred to as “minor depression,” minor depressive disorder is marked by at least two depressive symptoms that last over two weeks long.
Recurrent Brief Depression
This classification of depression indicates symptoms that last from two days to two weeks, occurring at least once a month for twelve months. It is a milder form of depression that is usually treated with therapy.
Adjustment Disorder with Depressed Mood
Occasionally, some single event or stressor can cause a psychological response so intense that it results in a mood low enough that it can be considered a type of depression. This condition is referred to as adjustment disorder with depressed mood. Usually, this condition is temporary.
There are a number of mood disorders that cause depression symptoms, but are not depression. It is essential to recognize that these disorders are not depression, because treatment for these other mood disorders may be very different than treatment for depression. Mood disorders causing depression symptoms include:
Bipolar Disorder or Manic Depression
Bipolar disorder is characterized by intense mood swings that range from deep depression to intense euphoria. People may experience shifts in mood a few times a year or several times a day. Bipolar disorder is a lifelong condition that can be managed through medication and therapy.
Cyclothymia or Cyclothymic Disorder
Cyclothymia is a milder form of bipolar disorder in which individuals suffer mood swings that range from moderate depression to euphoria. The mood swings are less severe than with bipolar disorder, and people with cyclothymia tend to stay grounded in reality. Cyclothymia is a long-term condition that may require lifelong treatment through medication and therapy.
Severe depression can be accompanied by psychotic symptoms such as delusions or hallucinations. The content of the psychotic delusions tend to be consistent with feelings of depression; for example, someone suffering from psychotic depression may hear voices telling them that they are worthless and don't deserve to live.
Written by: the Healthline Editorial Team
Medically reviewed by the Healthline Medical Team