Major depression significantly affects a person's family and personal relationships, work or school life, sleeping and eating habits, and general health. Its impact on functioning and well-being has been compared to that of other chronic medical conditions such as diabetes.

A person having a major depressive episode usually exhibits a very low mood, which pervades all aspects of life, and an inability to experience pleasure in activities that were formerly enjoyed. Depressed people may be preoccupied with, or ruminate over, thoughts and feelings of worthlessness, inappropriate guilt or regret, helplessness, hopelessness, and self-hatred. In severe cases, depressed people may have symptoms of psychosis. These symptoms include delusions or, less commonly, hallucinations, usually unpleasant. Other symptoms of depression include poor concentration and memory (especially in those with melancholic or psychotic features), withdrawal from social situations and activities, reduced sex drive, irritability, and thoughts of death or suicide. Insomnia is common among the depressed. In the typical pattern, a person wakes very early and cannot get back to sleep. Hypersomnia, or oversleeping, can also happen. Some antidepressants may also cause insomnia due to their stimulating effect.

A depressed person may report multiple physical symptoms such as fatigue, headaches, or digestive problems; physical complaints are the most common presenting problem in developing countries, according to the World Health Organization's criteria for depression. Appetite often decreases, with resulting weight loss, although increased appetite and weight gain occasionally occur. Family and friends may notice that the person's behavior is either agitated or lethargic. Older depressed people may have cognitive symptoms of recent onset, such as forgetfulness, and a more noticeable slowing of movements. Depression often coexists with physical disorders common among the elderly, such as stroke, other cardiovascular diseases, Parkinson's disease, and chronic obstructive pulmonary disease.

Depressed children may often display an irritable mood rather than a depressed mood, and show varying symptoms depending on age and situation. Most lose interest in school and show a decline in academic performance. They may be described as clingy, demanding, dependent, or insecure. Diagnosis may be delayed or missed when symptoms are interpreted as normal moodiness.

Depressive mixed states occur when patients experience depression and non-euphoric, usually subsyndromal, hypomania at the same time. As mentioned previously, it is particularly difficult to diagnose BP-II when a patient is in this state.

In a mixed state, mood is depressed, but the following symptoms of hypomania present as well:

- Irritability

- Mental overactivity

- Behavioral overactivity

Mixed states are associated with greater levels of suicidality than non-mixed depression. Antidepressants may increase this risk.

Minor depressive disorder is very similar to major depressive disorder in the symptoms present. Generally, a person's mood is affected by thoughts and feelings of being sad or down on themself or by a loss of interest in nearly all activities. People can experience ups and downs in their life everyday where an event, action, stress or many other factors can affect their feelings on that day. However, depression occurs when those feelings of sadness persist for longer than a few weeks.

A person is considered to have minor depressive disorder if they experience 2 to 4 depressive symptoms during a 2-week period. The Diagnostic and Statistical Manual of Mental Disorders lists the major depressive symptoms. Depressed mood most of the day and/or loss of interest or pleasure in normal activities must be experienced by the individual to be considered to have minor depressive disorder. Without either of these two symptoms, the disorder is not classified as minor depressive disorder. Other depressive symptoms include significant weight loss or weight gain without trying to diet (an increase/decrease in appetite can provide clues as well), insomnia or hypersomnia, psychomotor agitation or psychomotor retardation, fatigue or loss of energy, and feelings of worthlessness or excessive guilt.

All of these signs can compound on each other to create the last major symptom group of minor depressive disorder: thoughts of death, suicidal thoughts, plans to commit suicide, or a suicide attempt.

Minor depressive disorder differs from major depressive disorder in the number of symptoms present with 5 or more symptoms necessary for a diagnosis of major depressive disorder. Both disorders require either depressed mood or loss of interest or pleasure in normal activities to be one of the symptoms and the symptoms need to be present for two weeks or longer. Symptoms also must be present for the majority of the length of a day and present for a majority of the days in the two-week period. Diagnosis can only occur if the symptoms cause "clinically significant distress or impairment". Dysthymia consists of the same depressive symptoms, but its main differentiable feature is its longer-lasting nature as compared to minor depressive disorder. Dysthymia was replaced in the DSM-5 by persistent depressive disorder, which combined dysthymia with chronic major depressive disorder.

It is during depressive episodes that BP-II patients often seek help. Symptoms may be syndromal or subsyndromal. Depressive BP-II symptoms may include five or more of the below symptoms (at least one of them must be either depressed mood or loss of interest/pleasure). In order to be diagnosed, they need to be present only during the same two-week period, as a change from previous hypomanic functioning:

- Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feels sad, empty, or hopeless) or observation made by others (e.g., appears tearful). (Note: In children and adolescents, can be irritable mood.)

- Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day (as indicated by either subjective account or observation).

- Significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day. (Note: In children, consider failure to make expected weight gain.)

- Insomnia or hypersomnia nearly every day.

- Psychomotor agitation or retardation nearly every day (observable by others; not merely subjective feelings of restlessness or being slowed down).

- Fatigue or loss of energy nearly every day.

- Feelings of worthlessness or excessive or inappropriate guilt nearly every day (not merely self-reproach or guilt about being sick).

- Diminished ability to think or concentrate, possible irritability or indecisiveness, nearly every day (either by subjective account or as observed by others).

- Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, a suicide attempt, or a specific plan for committing suicide.

Evidence also suggests that BP-II is strongly associated with atypical depression. Essentially, this means that many BP-II patients exhibit reverse vegetative symptoms. BP-II patients may have a tendency to oversleep and overeat, while typically depressed patients sleep and eat less than usual.

Cyclothymia is characterized by short cycles of baseline, stable periods of not over two months and numerous swings between depression and hypomania that fail to meet the severity of sustained duration criterion for major affective syndromes for at least two years.

Depressive/dysthymic episodes. Symptoms of the "depressive/dysthymic phase" may include any of the following conditions:difficulty making decisions, problems concentrating, poor memory recall, guilt, self-criticism, low self-esteem, pessimism, self-destructive thinking, constant sadness, apathy, hopelessness, helplessness and irritability. Also common are quick temper, poor judgment, lack of motivation, social withdrawal, appetite change, lack of sexual desire, self-neglect, fatigue, insomnia and sleepiness.

Hypomanic episodes. Symptoms of the "hypomanic episode" may include any of the following conditions: unusually good mood or cheerfulness (euphoria), extreme optimism, inflated self-esteem, rapid speech, racing thoughts, aggressive or hostile behavior, lack of consideration for others, agitation, massively increased physical activity, risky behavior, spending sprees, increased drive to perform or achieve goals, increased sexual drive, decreased need for sleep, tendency to be easily distracted, and inability to concentrate.

Mania is a distinct period of at least one week of elevated or irritable mood, which can range from euphoria to delirium, and those experiencing hypo- or mania may exhibit three or more of the following behaviors: speak in a rapid, uninterruptible manner, short attention span, racing thoughts, increased goal-oriented activities, agitation, or they may exhibit behaviors characterized as impulsive or high-risk, such as hypersexuality or excessive spending. To meet the definition for a manic episode, these behaviors must impair the individual's ability to socialize or work. If untreated, a manic episode usually lasts three to six months.

People with hypomania or mania may experience a decreased need of sleep, impaired judgment, and speak excessively and very rapidly. Manic individuals often have a history of substance abuse developed over years as a form of "self-medication". At the more extreme, a person in a full blown manic state can experience psychosis; a break with reality, a state in which thinking is affected along with mood. They may feel unstoppable, or as if they have been "chosen" and are on a "special mission", or have other grandiose or delusional ideas. This may lead to violent behavior and, sometimes, hospitalization in an inpatient psychiatric hospital. The severity of manic symptoms can be measured by rating scales such as the Young Mania Rating Scale, though questions remain about the reliability of these scales.

The onset of a manic or depressive episode is often foreshadowed by sleep disturbances. Mood changes, psychomotor and appetite changes, and an increase in anxiety can also occur up to three weeks before a manic episode develops.

Hypomania is the milder form of mania, defined as at least four days of the same criteria as mania, but does not cause a significant decrease in the individual's ability to socialize or work, lacks psychotic features such as delusions or hallucinations, and does not require psychiatric hospitalization. Overall functioning may actually increase during episodes of hypomania and is thought to serve as a defense mechanism against depression by some. Hypomanic episodes rarely progress to full blown manic episodes. Some people who experience hypomania show increased creativity while others are irritable or demonstrate poor judgment.

Hypomania may feel good to some persons who experience it, though most people who experience hypomania state that the stress of the experience is very painful. Bipolar people who experience hypomania, however, tend to forget the effects of their actions on those around them. Even when family and friends recognize mood swings, the individual will often deny that anything is wrong. What might be called a "hypomanic event", if not accompanied by depressive episodes, is often not deemed problematic, unless the mood changes are uncontrollable, volatile, or mercurial. Most commonly, symptoms continue for a few weeks to a few months.

Recurrent brief depression (RBD) defines a mental disorder characterized by intermittent depressive episodes, not related to menstrual cycles in women, occurring between approximately 6-12 times per year, over at least one year or more fulfilling the diagnostic criteria for major depressive episodes (DSM-IV and ICD-10) except for duration which in RBD is less than 14 days, typically 2–4 days. Despite the short duration of the depressive episodes, such episodes are severe and suicidal ideation and impaired function is rather common. The majority of patients with RBD also report symptoms of anxiety and increased irritability. Hypersomnia is also rather frequent. About 1/2 of patients fulfilling diagnostic criteria for RBD may have additional short episodes of brief hypomania which is a severity marker of RBD. RBD may be the only mental disorder present, but RBD may also occur as part of a history of recurrent major depressive episodes or bipolar disorders. RBD is also seen among some patients with personality disorders.

Major depression frequently co-occurs with other psychiatric problems. The 1990–92 "National Comorbidity Survey" (US) reports that half of those with major depression also have lifetime anxiety and its associated disorders such as generalized anxiety disorder. Anxiety symptoms can have a major impact on the course of a depressive illness, with delayed recovery, increased risk of relapse, greater disability and increased suicide attempts. There are increased rates of alcohol and drug abuse and particularly dependence, and around a third of individuals diagnosed with ADHD develop comorbid depression. Post-traumatic stress disorder and depression often co-occur. Depression may also coexist with attention deficit hyperactivity disorder (ADHD), complicating the diagnosis and treatment of both. Depression is also frequently comorbid with alcohol abuse and personality disorders.

Depression and pain often co-occur. One or more pain symptoms are present in 65% of depressed patients, and anywhere from 5 to 85% of patients with pain will be suffering from depression, depending on the setting; there is a lower prevalence in general practice, and higher in specialty clinics. The diagnosis of depression is often delayed or missed, and the outcome can worsen if the depression is noticed but completely misunderstood.

Depression is also associated with a 1.5- to 2-fold increased risk of cardiovascular disease, independent of other known risk factors, and is itself linked directly or indirectly to risk factors such as smoking and obesity. People with major depression are less likely to follow medical recommendations for treating and preventing cardiovascular disorders, which further increases their risk of medical complications. In addition, cardiologists may not recognize underlying depression that complicates a cardiovascular problem under their care.

The lifetime prevalence of RBD has been estimated at 2.6 to 10.0%, and the one-year prevalence at 5.0-8.2%. The World Health Organization project on "Psychological problems in general health care", which was based on primary care samples, reported a one-year prevalence of 3.7 – 9.9%. However none of these studies differentiate between RBD with and without a history of other mood disorders (e.g. major depression). DSM-IV field trial estimated the life-time of RBD only to be about 2%.

Melancholic depression, or depression with melancholic features, is a DSM-IV subtype of clinical depression requiring at least one of the following symptoms:

- Anhedonia (the inability to find pleasure in positive things)

- Lack of mood reactivity (i.e. mood does not improve in response to positive events)

And at least three of the following:

- Depression that is subjectively different from grief or loss

- Severe weight loss or loss of appetite

- Psychomotor agitation or retardation

- Early morning awakening

- Guilt that is excessive

- Worse mood in the morning

Melancholic features apply to an episode of depression that occurs as part of either major depressive disorder or bipolar disorder I or II.

Melancholic depression is often considered to be a biologically based and particularly severe form of depression. Treatment involves antidepressants, electroconvulsive therapy, or other empirically supported treatments such as cognitive behavioral therapy and interpersonal therapy for depression. A 2008 analysis of a large study of patients with unipolar major depression found a rate of 23.5% for melancholic features. It was the first form of depression extensively studied, and many of the early symptom checklists for depression reflect this.

The incidence of melancholic depression has been found to increase when the temperature and/or sunlight are low.

According to the DSM-IV, the "melancholic features" specifier may be applied to the following only:

1. Major depressive episode, single episode

2. Major depressive episode, recurrent episode

3. Bipolar I disorder, most recent episode depressed

4. Bipolar II disorder, most recent episode depressed

The following are the revised criteria for a diagnosis of cyclothymic disorder (DSM-IV-TR 301.13) from the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-IV-TR):

- A. For at least 2 years (1 year in children and adolescents), the presence of numerous periods with hypomanic symptoms and numerous periods with depressive symptoms that do not meet criteria for a Major Depressive Episode

- B. During the above period, the person has not been without the symptoms in A for more than 2 months in the 2-year period

- C. No Major Depressive Episode, Manic Episode, or Mixed Episode has been present during the first 2 years of the disturbance.

- D. The symptoms in Criterion A are not better accounted for by Schizoaffective Disorder and are not superimposed on Schizophrenia, Schizophreniform Disorder, Delusional Disorder, or Psychotic Disorder Not Otherwise Specified.

- E. The symptoms are not due to the direct physiological effects of a substance (e.g. drug of abuse, a medication) or a general medical condition (e.g., hyperthyroidism).

- F. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

The DSM-IV-TR notes that the mood disturbance must be not severe enough to constitute a full-fledged manic or major depressive episode. The diagnosis requires that there be periods of both hypomania and depression and that periods of normal mood not last longer than 2 months.

The DSM-IV-TR also notes that Cyclothymia and borderline personality disorder share similar features and that individuals can be diagnosed with both BPD and Cyclothymia depending on the symptoms they present.

Minor depressive disorder, also known as minor depression, is a mood disorder that does not meet the full criteria for major depressive disorder but at least two depressive symptoms are present for two weeks. These symptoms can be seen in many different psychiatric and mental disorders, which can lead to more specific diagnoses of an individual's condition. However, some of the situations might not fall under specific categories listed in the "Diagnostic and Statistical Manual of Mental Disorders". Minor depressive disorder is an example of one of these nonspecific diagnoses, as it is a disorder classified in the DSM-IV-TR under the category Depressive Disorder Not Otherwise Specified (DD-NOS). The classification of NOS depressive disorders is up for debate. Minor depressive disorder as a term was never an officially accepted term, but was listed in Appendix B of the DSM-IV-TR. This is the only version of the DSM that contains the term, as the prior versions and the most recent edition, DSM-5, does not mention it.

A person is considered to have minor depressive disorder if they experience 2 to 4 depressive symptoms, with one of them being either depressed mood or loss of interest or pleasure, during a 2-week period. The person must not have experienced the symptoms for 2 years and there must not have been one specific event that caused the symptoms to arise. Although not all cases of minor depressive disorder are deemed in need of treatment, some cases are treated similarly to major depressive disorder. This treatment includes cognitive behavioral therapy (CBT), anti-depressant medication, and combination therapy. A lot of research supports the notion that minor depressive disorder is an early stage of major depressive disorder, or that it is simply highly predictive of subsequent major depressive disorder.

SAD is a type of major depressive disorder, and sufferers may exhibit any of the associated symptoms, such as feelings of hopelessness and worthlessness, thoughts of suicide, loss of interest in activities, withdrawal from social interaction, sleep and appetite problems, difficulty with concentrating and making decisions, decreased sex drive, a lack of energy, or agitation. Symptoms of winter SAD often include oversleeping or difficulty waking up in the morning, nausea, and a tendency to over eat, often with a craving for carbohydrates, which leads to weight gain. SAD is typically associated with winter depression, but springtime lethargy or other seasonal mood patterns are not uncommon. Although each individual case is different, in contrast to winter SAD, people who experience spring and summer depression may be more likely to show symptoms such as insomnia, decreased appetite and weight loss, and agitation or anxiety.

"With seasonal pattern" is a specifier for "bipolar and related disorders", including bipolar I disorder and bipolar II disorder.

Most people with SAD experience major depressive disorder, but as many as 20% may have a bipolar disorder. It is important to discriminate between diagnoses because there are important treatment differences. In these cases, people who have the "With seasonal pattern" specifier may experience a depressive episode either due to major depressive disorder or as part of bipolar disorder during the winter and remit in the summer. Around 25% of patients with bipolar disorder may present with a depressive seasonal pattern, which is associated with bipolar II disorder, rapid cycling, eating disorders, and more depressive episodes. Gender displays distinct clinical characteristics associated to seasonal pattern: males present with more Bipolar II disorder and a higher number of depressive episodes, and females with rapid cycling and eating disorders.

Depressive Disorder Not Otherwise Specified (DD-NOS) is designated by the code "311" in the DSM-IV for depressive disorders that are impairing but do not fit any of the officially specified diagnoses. According to the DSM-IV, DD-NOS encompasses "any depressive disorder that does not meet the criteria for a specific disorder." In the DSM-5, it is called unspecified depressive disorder.

Examples of disorders in this category include those sometimes described as minor depressive disorder and recurrent brief depression.

"Depression" refers to a spectrum of disturbances in mood that vary from mild to severe and from short periods to constant illness. DD-NOS is diagnosed if a patients symptoms fail to meet the criteria more common depressive disorders such as major depressive disorder or dysthymia. Although DD-NOS shares similar symptoms to dysthymia, dysthymia is classified by a period of at least 2 years of constantly recurring depressed mood, where as DD-NOS is classified by much shorter periods of depressed moods.

For most people who suffer the condition, their life will be significantly affected. DD-NOS can make many aspects of a person's daily life difficult to manage, inhibiting their ability to enjoy the things that used to make them happy. Sufferers of the disorder tend to isolate themselves from their friends and families, lose interest in some activities, and experience behavioural changes and sleeping disorders. Some sufferers also experience suicidal tendencies or suicide attempts. In addition to having these symptoms, a diagnosis of DD-NOS will only be made if the symptoms cause significant distress or impairment in social, occupational, or other important areas of functioning. For the diagnosis to be accurate, a psychiatrist is required to spend extensive time with the patient.

Symptoms of the disorder may arise due to several reasons. These include:

- Distress due to medical conditions

- Environmental effects and situations

However, the effects of drugs or medication or bereavement are not classified under the diagnosis.

A person will not be diagnosed with the condition if they have or have had any of the following: a major depressive episode, manic episode, mixed episode or hypomanic episode.

A diagnosis of the disorder will look like: "Depressive Disorder NOS 311".

The disorder is characterized by a sudden onset of psychotic symptoms, which may include delusions, hallucinations, disorganized speech or behavior, or catatonic behavior. The symptoms must not be caused by schizophrenia, schizoaffective disorder, delusional disorder or mania in bipolar disorder. They must also not be caused by a drug (such as amphetamines) or medical condition (such as a brain tumor). The term bouffée délirante describes an acute nonaffective and nonschizophrenic psychotic disorder, which is largely similar to DSM-III-R and DSM-IV brief psychotic and schizophreniform disorders.

Symptoms generally last at least a day, but not more than a month, and there is an eventual return to full baseline functioning. It may occur in response to a significant stressor in one's life, or in other situations where a stressor is not apparent, including in the weeks following birth. In diagnosis, a careful distinction is considered for culturally appropriate behaviors, such as religious beliefs and activities. It is believed to be connected to or synonymous with a variety of culture-specific phenomena such as latah, koro, and amok.

There are three forms of brief psychotic disorder:

1. Brief psychotic disorder with a stressor, such as a trauma or death in the family.

2. Brief psychotic disorder without a stressor, there is no obvious stressor.

3. Brief psychotic disorder with postpartum onset. Usually occurs about four weeks after giving birth.

Postpartum depression onset usually begins between two weeks to a month after delivery. Recent studies have shown that 50% of postpartum depressive episodes begin prior to delivery. Therefore, in the DSM-5 postpartum depression is diagnosed under "depressive disorder with peripartum onset", in which "peripartum onset" is defined as anytime either during pregnancy or within the four weeks following delivery. PPD may last several months or even a year. Postpartum depression can also occur in women who have suffered a miscarriage.

Symptoms of PPD can occur any time in the first year postpartum. Typically, a diagnosis of postpartum depression is considered after signs and symptoms persist for at least two weeks. These symptoms include, but are not limited to:

311- Depressive Disorder Not Otherwise Specified (NOS)

The Depressive disorder NOS category includes disorders with depressive features that do not meet the criteria for Major Depressive Disorder, Dysthymic disorder, Adjustment Disorder with Depressed Mood or Adjustment Disorder with Mixed Anxiety and Depressed Mood. Sometimes depressive symptoms can present as part of an Anxiety Disorder Not otherwise Specified. Examples of Depressive Disorder Not Otherwise Specified include.

- Premenstrual Dysphoric Disorder: in most menstrual cycles during the past years, (e.g., markedly depressed mood, marked anxiety, marked affective lability, or decreased interest in activities) regularly occurred during the onset of menses. These symptoms must be severe enough to markedly interfere with work, school, or usual activities and be entirely absent for at least 1 week post menses.

- Minor depressive disorder: episodes of at least 2 weeks of depressive symptoms but with fewer than the five items required for Major Depressive Disorder.

- Recurrent brief depressive disorder: depressive episodes lasting from 2 days up to 2 weeks, occurring at least once a month for 12 months (not associated with the menstrual cycle)

- Post psychotic depressive Disorder of schizophrenia: a Major Depressive Episode that occurs during the residual phase of schizophrenia.

- A Major Depressive Episode superimposed on delusional disorder, Psychotic Disorder Not Otherwise Specified, or the active phase of schizophrenia.

- Situations in which the clinician has concluded that a depressive disorder is present but is unable to determine whether it is primary, due to a general medical condition, or substance induced.

Symptoms of the disorder may arise due to several reasons. These include:

- Distress due to medical conditions

- Environmental effects and situations

This is described as a rare form of severe mental illness, with the following characteristics:

- Sudden onset in a previously asymptomatic person.

- Brief duration, with full recovery.

- Psychotic symptoms that can include confusion or hallucinations, mutism and stupor, delusions, or manic state. These are distinct from premenstrual tension, premenstrual syndrome, premenstrual (late luteal phase) depression or dysphoric disorder or menstrual mood disorder.

- Occurrence in rhythm with the menstrual cycle.

It shares clinical features with, and presents similarly to, postpartum psychosis. Researchers Deuchar and Brockington proposed that a sudden drop in levels of estrogen in the brain could be the trigger for both conditions.

Brief psychotic disorder is a period of psychosis whose duration is generally shorter, is not always non-recurring, but can be, and is not caused by another condition.

The causes of melancholic-type major depressive disorder are believed to be mostly biological factors; some may have inherited the disorder from their parents. Sometimes stressful situations can trigger episodes of melancholic depression, though this is a contributing cause rather than a necessary or sufficient cause. People with psychotic symptoms are also thought to be more susceptible to this disorder. It is frequent in old age and often unnoticed by some physicians who perceive the symptoms to be a part of dementia. Major depressive disorder, melancholic or otherwise, is a separate condition that can be comorbid with dementia in the elderly.

According to the DSM IV-TR, the development of the emotional or behavioral symptoms of this diagnosis have to occur within three months of the onset of the identifiable stressor(s). Some emotional signs of adjustment disorder are:

However, the stress-related disturbance does not only exist as an exacerbation of a pre-existing axis I or axis II disorder and cannot be diagnostic as axis 1 disorder.

Suicidal behavior is prominent among people with AD of all ages, and up to one-fifth of adolescent suicide victims may have an adjustment disorder. Bronish and Hecht (1989) found that 70% of a series of patients with AD attempted suicide immediately before their index admission and they remitted faster than a comparison group with major depression. Asnis et al. (1993) found that AD patients report persistent ideation or suicide attempts less frequently than those diagnosed with major depression. According to a study on 82 AD patients at a clinic, Bolu et al. (2012) found that 22 (26.8%) of these patients were admitted due to suicide attempt, consistent with previous findings. In addition, it was found that 15 of these 22 patients chose suicide methods that involved high chances of being saved. Henriksson et al. (2005) states statistically that the stressors are of one-half related to parental issues and one-third in peer issues.

An adjustment disorder (AD)—sometimes called exogenous, reactive, or situational depression—occurs when an individual is unable to adjust to or cope with a particular stress or a major life event. Since people with this disorder normally have symptoms that depressed people do, such as general loss of interest, feelings of hopelessness and crying, this disorder is sometimes known as situational depression. Unlike major depression, the disorder is caused by an outside stressor and generally resolves once the individual is able to adapt to the situation. One hypothesis about AD is that it may represent a sub-threshold clinical syndrome.

The condition is different from anxiety disorder, which lacks the presence of a stressor, or post-traumatic stress disorder and acute stress disorder, which usually are associated with a more intense stressor.

Common characteristics of AD include mild depressive symptoms, anxiety symptoms, and traumatic stress symptoms or a combination of the three. There are nine types of AD listed in the DSM-III-R. According to the DSM-IV-TR, there are six types of AD, which are characterized by the following predominant symptoms: depressed mood, anxiety, mixed depression and anxiety, disturbance of conduct, mixed disturbance of emotions and conduct, and unspecified. However, the criteria for these symptoms are not specified in greater detail. AD may be acute or chronic, depending on whether it lasts more or less than six months. According to the DSM-IV-TR, if the AD lasts less than 6 months, then it may be considered acute. If it lasts more than six months, it may be considered chronic. Moreover, the symptoms cannot last longer than six months after the stressor(s), or its consequences, have terminated. Diagnosis of AD is quite common; there is an estimated incidence of 5%–21% among psychiatric consultation services for adults. Adult women are diagnosed twice as often as are adult men. Among children and adolescents, girls and boys are equally likely to receive this diagnosis. AD was introduced into the psychiatric classification systems almost 30 years ago, but similar syndromes were recognized for many years before that.