The internalizing disorders, with high levels of negative affectivity, include depressive disorders, anxiety disorders, obsessive-compulsive and related disorders, trauma and stressor-related disorders, and dissociative disorders. Others like bulimia, and anorexia also come under this category.

Behaviors that are apparent in those with internalizing disorders include depression, withdrawal, anxiety, and loneliness. There are also behavioral characteristics involved with internalizing disorders. Some behavioral abnormalities include poor self-esteem, suicidal behaviors, decreased academic progress, and social withdrawal. Internalizing one's problems, like sadness, can cause the problems to grow into larger burdens such as social withdrawal, suicidal behaviors or thoughts, and other unexplained physical symptoms.

Externalizing disorders often involve emotion dysregulation problems and impulsivity that are manifested as antisocial behavior and aggression in opposition to authority, societal norms, and often violate the rights of others. Some examples of externalizing disorder symptoms include, often losing one's temper, excessive verbal aggression, physical aggression to people and animals, destruction of property, theft, and deliberate fire setting. As with all DSM-5 mental disorders, an individual must have functional impairment in at least one domain (e.g., academic, occupational, social relationships, or family functioning) in order to meet diagnostic criteria for an externalizing disorder. Moreover, an individual's symptoms should be atypical for their cultural and environmental context and physical medical conditions should be ruled out before an externalizing disorder diagnosis is considered. Diagnoses must be made by qualified mental health professionals. DSM-5 classifications of externalizing disorders are listed herein, however, can also be used to classify externalizing disorders. More specific criteria and examples of symptoms for various externalizing disorders can be found in the DSM-5.

There are no specific criteria for "externalizing behavior" or "externalizing disorders." Thus, there is no clear classification of what constitutes an externalizing disorder in the DSM-5. Attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), antisocial personality disorder(ASPD), pyromania, kleptomania, intermittent explosive disorder (IED), and substance-related disorders are frequently referred to as externalizing disorders. Disruptive mood dysregulation disorder has also been posited as an externalizing disorder, but little research has examined and validated it to date given its recent addition to the DSM-5, and thus, it is not included further herein.

The likely course and outcome of mental disorders varies and is dependent on numerous factors related to the disorder itself, the individual as a whole, and the social environment. Some disorders are transient, while others may be more chronic in nature.

Even those disorders often considered the most serious and intractable have varied courses i.e. schizophrenia, psychotic disorders, and personality disorders. Long-term international studies of schizophrenia have found that over a half of individuals recover in terms of symptoms, and around a fifth to a third in terms of symptoms and functioning, with some requiring no medication. At the same time, many have serious difficulties and support needs for many years, although "late" recovery is still possible. The World Health Organization concluded that the long-term studies' findings converged with others in "relieving patients, carers and clinicians of the chronicity paradigm which dominated thinking throughout much of the 20th century."

Around half of people initially diagnosed with bipolar disorder achieve syndromal recovery (no longer meeting criteria for the diagnosis) within six weeks, and nearly all achieve it within two years, with nearly half regaining their prior occupational and residential status in that period. However, nearly half go on to experience a new episode of mania or major depression within the next two years. Functioning has been found to vary, being poor during periods of major depression or mania but otherwise fair to good, and possibly superior during periods of hypomania in Bipolar II.

One of the symptoms of conduct disorder is a lower level of fear. Research performed on the impact of toddlers exposed to fear and distress shows that negative emotionality (fear) predicts toddlers' empathy-related response to distress. The findings support that if a caregiver is able to respond to infant cues, the toddler has a better ability to respond to fear and distress. If a child does not learn how to handle fear or distress the child will be more likely to lash out at other children. If the caregiver is able to provide therapeutic intervention teaching children at risk better empathy skills, the child will have a lower incident level of conduct disorder.

Avoidant individuals often choose jobs of isolation so that they do not have to interact with the public regularly, due to their anxiety and fear of embarrassing themselves in front of others. Some with this disorder may fantasize about idealized, accepting, and affectionate relationships, due to their desire to belong. Individuals with the disorder tend to describe themselves as uneasy, anxious, lonely, unwanted and isolated from others. They often feel themselves unworthy of the relationships they desire, so they shame themselves from ever attempting to begin them.

People with avoidant personality disorder are preoccupied with their own shortcomings and form relationships with others only if they believe they will not be rejected. Loss and social rejection are so painful that these individuals will choose to be alone rather than risk trying to connect with others (see rejection sensitivity). They often view themselves with contempt, while showing an increased inability to identify traits within themselves that are generally considered as positive within their societies.

- Hypersensitivity to rejection and criticism

- Self-imposed social isolation

- Extreme shyness or anxiety in social situations, though the person feels a strong desire for close relationships

- Avoids physical contact because it has been associated with an unpleasant or painful stimulus

- Feelings of inadequacy

- Drastically reduced or absent self-esteem

- Self-loathing, autophobia or self-harm

- Mistrust of others or oneself; exhibits heightened self-doubt

- Emotional distancing related to intimacy

- Highly self-conscious

- Self-critical about their problems relating to others

- Heightened attachment-related anxiety, which may include a fear of abandonment

- Problems in occupational functioning

- Lonely self-perception, although others may find the relationship with them meaningful

- Feeling inferior to others

- Substance abuse and/or dependence

- In some extreme cases, agoraphobia

- Uses fantasy as a form of escapism to interrupt painful thoughts

In ICD-10, the latest version of the International Statistical Classification of Diseases and Related Health Problems, somatization syndrome is described as:

ICD-10 also includes the following subgroups of somatization syndrome:

- Undifferentiated somatoform disorder

- Hypochondriasis

- Somatoform autonomic dysfunction

- Persistent somatoform pain disorder

- Other somatoform disorders, such ones predominated by dysmenorrhoea, dysphagia, pruritus and torticollis

- Somatoform disorder, unspecified

Somatic symptom disorders are a group of disorders, all of which fit the definition of physical symptoms similar to those observed in physical disease or injury for which there is no identifiable physical cause. As such, they are a diagnosis of exclusion. Somatic symptoms may be generalized in four major medical categories: neurological, cardiac, pain, and gastrointestinal somatic symptoms.

A somatic symptom disorder, formerly known as a somatoform disorder, is any mental disorder which manifests as physical symptoms that suggest illness or injury, but which cannot be explained fully by a general medical condition or by the direct effect of a substance, and are not attributable to another mental disorder (e.g., panic disorder). Somatic symptom disorders, as a group, are included in a number of diagnostic schemes of mental illness, including the "Diagnostic and Statistical Manual of Mental Disorders". (Before DSM-5 this disorder was split into "somatization disorder" and "undifferentiated somatoform disorder".)

In people who have been diagnosed with a somatic symptom disorder, medical test results are either normal or do not explain the person's symptoms, and history and physical examination do not indicate the presence of a known medical condition that could cause them, though it is important to note that the DSM-5 cautions that this alone is not sufficient for diagnosis. The patient must also be excessively worried about their symptoms, and this worry must be judged to be out of proportion to the severity of the physical complaints themselves. A diagnosis of somatic symptom disorder requires that the subject have recurring somatic complaints for at least six months.

Symptoms are sometimes similar to those of other illnesses and may last for years. Usually, the symptoms begin appearing during adolescence, and patients are diagnosed before the age of 30 years. Symptoms may occur across cultures and gender. Other common symptoms include anxiety and depression. However, since anxiety and depression are also very common in persons with confirmed medical illnesses, it remains possible that such symptoms are a consequence of the physical impairment, rather than a cause. Somatic symptom disorders are not the result of conscious malingering (fabricating or exaggerating symptoms for secondary motives) or factitious disorders (deliberately producing, feigning, or exaggerating symptoms). Somatic symptom disorder is difficult to diagnose and treat. Some advocates of the diagnosis believe this is because proper diagnosis and treatment requires psychiatrists to work with neurologists on patients with this disorder.

Emotional dysregulation in children can be associated with externalizing behaviors including

- exhibiting more extreme emotions

- difficulty identifying emotional cues

- difficulty recognizing their own emotions

- focusing on the negative

- difficulty controlling their attention

- being impulsive

- difficulty decreasing their negative emotions

- difficulty calming down when upset

In the DSM-5 the disorder has been renamed somatic symptom disorder (SSD), and includes SSD with predominantly somatic complaints (previously referred to as somatization disorder), and SSD with pain features (previously known as pain disorder).

Emotional dysregulation in children can be associated with internalizing behaviors including

- exhibiting emotions too intense for a situation

- difficulty calming down when upset

- difficulty decreasing negative emotions

- being less able to calm themselves

- difficulty understanding emotional experiences

- becoming avoidant or aggressive when dealing with negative emotions

- experiencing more negative emotions

The affective spectrum is a spectrum of affective disorders (mood disorders). It is a grouping of related psychiatric and medical disorders which may accompany bipolar, unipolar, and schizoaffective disorders at statistically higher rates than would normally be expected. These disorders are identified by a common positive response to the same types of pharmacologic treatments. They also aggregate strongly in families and may therefore share common heritable underlying physiologic anomalies.

Affective spectrum disorders include:

- Attention deficit hyperactivity disorder

- Bipolar disorder

- Body dysmorphic disorder

- Bulimia nervosa and other eating disorders

- Cataplexy

- Dysthymia

- Generalized anxiety disorder

- Hypersexuality

- Irritable bowel syndrome

- Impulse-control disorders

- Kleptomania

- Migraine

- Major depressive disorder

- Obsessive-compulsive disorder

- Oppositional defiant disorder

- Panic disorder

- Posttraumatic stress disorder

- Premenstrual dysphoric disorder

- Social anxiety disorder

- Fibromyalgia

The following may also be part of the spectrum accompanying affective disorders.

- Chronic pain

- Intermittent explosive disorder

- Pathological gambling

- Personality disorder

- Pyromania

- Substance abuse and addiction (includes alcoholism)

- Trichotillomania

Also, there are now studies linking heart disease.

Many of the terms above overlap. The American Psychiatric Association's definitions of these terms can be found in the "Diagnostic and Statistical Manual of Mental Disorders" (DSM).

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".

Additionally, requirements for a proposed diagnosis such as the number and duration of symptoms and the impact on functioning are continuing to be investigated. But there is no doubt that both ADHD and SCT are found in children and adults and are linked to significant impairment and a diminished quality of life (QoL). The research by Barkley suggests that this is especially true if ADHD and SCT occur together: In adults, those comorbid cases were more likely to be unmarried and to be out of work on disability compared to cases with ADHD alone. But SCT alone is also present in the population and can be quite impairing in educational and occupational settings, even if it is not as pervasively impairing as ADHD.

A mental disorder, also called a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitting, or occur as a single episode. Many disorders have been described, with signs and symptoms that vary widely between specific disorders. Such disorders may be diagnosed by a mental health professional.

The causes of mental disorders are often unclear. Theories may incorporate findings from a range of fields. Mental disorders are usually defined by a combination of how a person behaves, feels, perceives, or thinks. This may be associated with particular regions or functions of the brain, often in a social context. A mental disorder is one aspect of mental health. Cultural and religious beliefs, as well as social norms, should be taken into account when making a diagnosis.

Services are based in psychiatric hospitals or in the community, and assessments are carried out by psychiatrists, psychologists, and clinical social workers, using various methods but often relying on observation and questioning. Treatments are provided by various mental health professionals. Psychotherapy and psychiatric medication are two major treatment options. Other treatments include social interventions, peer support, and self-help. In a minority of cases there might be involuntary detention or treatment. Prevention programs have been shown to reduce depression.

Common mental disorders include depression, which affects about 400 million, dementia which affects about 35 million, and schizophrenia, which affects about 21 million people globally. Stigma and discrimination can add to the suffering and disability associated with mental disorders, leading to various social movements attempting to increase understanding and challenge social exclusion.

In many ways, those who have an SCT profile have some of the opposite symptoms of those with classic ADHD: instead of being hyperactive, extroverted, obtrusive, excessively energetic and risk takers, those with SCT are drifting, absent-minded, listless, introspective and daydreamy. They feel as if "in the fog" and seem "out of it".

The comorbid psychiatric problems often associated with SCT are more often of the internalizing types, such as anxiety, unhappiness or depression. Most consistent across studies was a pattern of reticence and social withdrawal in interactions with peers. Their typically shy nature and slow response time has often been misinterpreted as aloofness or disinterest by others. In social group interactions, those with SCT may be ignored. People with classic ADHD are more likely to be rejected in these situations, because of their social intrusiveness or aggressive behavior. Compared to children with SCT, they are also much more likely to show antisocial behaviours like substance abuse, oppositional-defiant disorder or conduct disorder (frequent lying, stealing, fighting etc.). Fittingly, in terms of personality, ADHD seems to be associated with sensitivity to reward and fun seeking while SCT may be associated with punishment sensitivity.

Children with conduct disorder have a high risk of developing other adjustment problems. Specifically, risk factors associated with conduct disorder and the effects of conduct disorder symptomatology on a child's psychosocial context have been linked to overlap with other psychological disorders. In this way, there seems to be reciprocal effects of comorbidity with certain disorders, leading to increased overall risk for these youth.

People with HPD are usually high-functioning, both socially and professionally. They usually have good social skills, despite tending to use them to manipulate others into making them the center of attention. HPD may also affect a person's social and/or romantic relationships, as well as their ability to cope with losses or failures. They may seek treatment for clinical depression when romantic (or other close personal) relationships end.

Individuals with HPD often fail to see their own personal situation realistically, instead dramatizing and exaggerating their difficulties. They may go through frequent job changes, as they become easily bored and may prefer withdrawing from frustration (instead of facing it). Because they tend to crave novelty and excitement, they may place themselves in risky situations. All of these factors may lead to greater risk of developing clinical depression.

Additional characteristics may include:

- Exhibitionist behavior

- Constant seeking of reassurance or approval

- Excessive sensitivity to criticism or disapproval

- Pride of own personality and unwillingness to change, viewing any change as a threat

- Inappropriately seductive appearance or behavior of a sexual nature

- Using somatic symptoms (of physical illness) to garner attention

- A need to be the center of attention

- Low tolerance for frustration or delayed gratification

- Rapidly shifting emotional states that may appear superficial or exaggerated to others

- Tendency to believe that relationships are more intimate than they actually are

- Making rash decisions

- Blaming personal failures or disappointments on others

- Being easily influenced by others, especially those who treat them approvingly

- Being overly dramatic and emotional

Some people with histrionic traits or personality disorder change their seduction technique into a more maternal or paternal style as they age.

The DSM-IV defines depressive personality disorder as "a pervasive pattern of depressive cognitions and behaviors beginning by early adulthood and occurring in a variety of contexts." Depressive personality disorder occurs before, during, and after major depressive episodes, making it a distinct diagnosis not included in the definition of either major depressive episodes or dysthymic disorder. Specifically, five or more of the following must be present most days for at least two years in order for a diagnosis of depressive personality disorder to be made:

- Usual mood is dominated by dejection, gloominess, cheerlessness, joylessness and unhappiness

- Self-concept centres on beliefs of inadequacy, worthlessness and low self-esteem

- Is critical, blaming and derogatory towards the self

- Is brooding and given to worry

- Is negativistic, critical and judgmental toward others

- Is pessimistic

- Is prone to feeling guilty or remorseful

People with depressive personality disorder have a generally gloomy outlook on life, themselves, the past and the future. They are plagued by issues developing and maintaining relationships. In addition, studies have found that people with depressive personality disorder are more likely to seek psychotherapy than people with Axis I depression spectrums diagnoses.

Recent studies have concluded that people with depressive personality disorder are at a greater risk of developing dysthymic disorder than a comparable group of people without depressive personality disorder. These findings lead to the fact that depressive personality disorder is a potential precursor to dysthymia or other depression spectrum diagnoses. If included in the DSM-V, depressive personality disorder would be included as a warning sign for potential development of more severe depressive episodes.

Researchers at McLean Hospital in Massachusetts looked at the comorbidity of depressive personality disorder and a variety of other disorders. It was found that subjects with depressive personality disorder were more likely than the subjects without depressive personality disorder to currently have major depression and an eating disorder. Subjects with and without depressive personality disorder were statistically equally likely to have any of the other disorders examined.

The following conditions commonly coexist (comorbid) with dependent personality disorder:

- mood disorders

- anxiety disorders

- adjustment disorder

- borderline personality disorder

- avoidant personality disorder

- histrionic personality disorder

Avoidant personality disorder (AvPD) is a Cluster C personality disorder. Those affected display a pattern of severe social anxiety, social inhibition, feelings of inadequacy and inferiority, extreme sensitivity to negative evaluation, and avoidance of social interaction despite a strong desire for intimacy. The behavior is usually noticed by early adulthood and occurs in most situations.

People with AvPD often consider themselves to be socially inept or personally unappealing and avoid social interaction for fear of being ridiculed, humiliated, rejected or disliked. They generally avoid becoming involved with others unless they are certain they will be liked. As the name suggests, the main coping mechanism of those with avoidant personality disorder is avoidance of feared stimuli. Both childhood emotional neglect (in particular, the rejection of a child by one or both parents) and peer group rejection are associated with an increased risk for its development; however, it is possible for AvPD to occur without any notable history of abuse or neglect.

While some scientists claim the exact causes for the disorder are unknown, others found that parents of avoidant children seemed to have difficulty with their own negative emotions. Some researchers have also theorized that certain cases of AvPD may occur when individuals with innately high sensory processing sensitivity (characterized by deeper processing of physical and emotional stimuli, alongside high levels of empathy) are raised in abusive, negligent or otherwise dysfunctional environments, which inhibits their ability to form secure bonds with others.

In the American Psychiatric Association's DSM-5, schizotypal personality disorder is defined as a "pervasive pattern of social and interpersonal deficits marked by acute discomfort with, and reduced capacity for, close relationships as well as by cognitive or perceptual distortions and eccentricities of behavior, beginning by early adulthood and present in a variety of contexts."

At least five of the following symptoms must be present: ideas of reference, strange beliefs or magical thinking, abnormal perceptual experiences, strange thinking and speech, paranoia, inappropriate or constricted affect, strange behavior or appearance, lack of close friends, and excessive social anxiety that does not abate and stems from paranoia rather than negative judgments about self. These symptoms must not occur only during the course of a disorder with similar symptoms (such as schizophrenia or autism spectrum disorder).

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