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.

Intermittent explosive disorder (sometimes abbreviated as IED) is a behavioral disorder characterized by explosive outbursts of anger and violence, often to the point of rage, that are disproportionate to the situation at hand (e.g., impulsive screaming triggered by relatively inconsequential events). Impulsive aggression is not premeditated, and is defined by a disproportionate reaction to any provocation, real or perceived. Some individuals have reported affective changes prior to an outburst (e.g., tension, mood changes, energy changes, etc.).

The disorder is currently categorized in the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5) under the "Disruptive, Impulse-Control, and Conduct Disorders" category. The disorder itself is not easily characterized and often exhibits comorbidity with other mood disorders, particularly bipolar disorder. Individuals diagnosed with IED report their outbursts as being brief (lasting less than an hour), with a variety of bodily symptoms (sweating, stuttering, chest tightness, twitching, palpitations) reported by a third of one sample. Aggressive acts are frequently reported accompanied by a sensation of relief and in some cases pleasure, but often followed by later remorse.

The current DSM-5 criteria for Intermittent Explosive Disorder include:

- Recurrent outbursts that demonstrate an inability to control impulses, including either of the following:

- Verbal aggression (tantrums, verbal arguments or fights) or physical aggression that occurs twice in a week-long period for at least three months and does not lead to destruction of property or physical injury (Criterion A1)

- Three outbursts that involve injury or destruction within a year-long period (Criterion A2)

- Aggressive behavior is grossly disproportionate to the magnitude of the psychosocial stressors (Criterion B)

- The outbursts are not premeditated and serve no premeditated purpose (Criterion C)

- The outbursts cause distress or impairment of functioning, or lead to financial or legal consequences (Criterion D)

- The individual must be at least six years old (Criterion E)

- The recurrent outbursts cannot be explained by another mental disorder and are not the result of another medical disorder or substance use (Criterion F)

It is important to note that DSM-5 now includes two separate criteria for types of aggressive outbursts (A1 and A2) which have empirical support:

- Criterion A1: Episodes of verbal and/or non damaging, nondestructive, or non injurious physical assault that occur, on average, twice weekly for three months. These could include temper tantrums, tirades, verbal arguments/fights, or assault without damage. This criterion includes high frequency/low intensity outbursts.

- Criterion A2: More severe destructive/assaultive episodes which are more infrequent and occur, on average, three times within a twelve-month period. These could be destroying an object without regard to value, assaulting an animal or individual. This criterion includes high-intensity/low-frequency outbursts.

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 signs and symptoms of impulse-control disorders vary based on the age of the persons suffering from them, the actual type of impulse-control that they are struggling with, the environment in which they are living, and whether they are male, female, or other.

Intermittent explosive disorder or IED is a clinical condition of experiencing recurrent aggressive episodes that are out of proportion of any given stressor. Earlier studies reported a prevalence rate between 1%-2% in a clinical setting, however a study done by Coccaro and colleagues in 2004 had reported about 11.1% lifetime prevalence and 3.2% one month prevalence in a sample of a moderate number of individuals (n=253). Based on the study, Coccaro and colleagues estimated the prevalence of IED in 1.4 million individuals in the US and 10 million with lifetime IED.

Though the American Psychiatric Association's criteria for attention deficit hyperactivity disorder (ADHD), and the World Health Organization's criteria for hyperkinetic disorder each list a very similar set of 18 symptoms, the differing rules governing diagnosis mean that hyperkinetic disorder features greater impairment and more impulse-control difficulties than typical ADHD, and it most resembles a severe case of ADHD combined type.

Unlike ADHD, a diagnosis of hyperkinetic disorder requires that the clinician directly observes the symptoms (rather than relying only on parent and teacher reports); that onset must be by age 6 not 7; and that at least six inattention, three hyperactivity and one impulsivity symptom be present in two or more settings. While ADHD may exist comorbid with (in the presence of) mania or a depressive or anxiety disorder, the presence of one of these rules out a diagnosis of hyperkinetic disorder. Most cases of hyperkinetic disorder appear to meet the broader criteria of ADHD.

Hyperkinetic disorder may exist comorbid with conduct disorder, in which case the diagnosis is hyperkinetic conduct disorder.

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).

The rate in school age children is thought to be about 1.5%, compared with an estimated 5.3% for ADHD.

Dual diagnosis (also called co-occurring disorders, COD, or dual pathology) is the condition of suffering from a mental illness and a comorbid substance abuse problem. There is considerable debate surrounding the appropriateness of using a single category for a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcoholism, or it can be restricted to specify severe mental illness (e.g. psychosis, schizophrenia) and substance misuse disorder (e.g. cannabis abuse), or a person who has a milder mental illness and a drug dependency, such as panic disorder or generalized anxiety disorder and is dependent on opioids. Diagnosing a primary psychiatric illness in substance abusers is challenging as drug abuse itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness.

Those with co-occurring disorders face complex challenges. They have increased rates of relapse, hospitalization, homelessness, and HIV and hepatitis C infection compared to those with either mental or substance use disorders alone. The cause of co-occurring disorders is unknown, although there are several theories.

Individual factors that can lead to pyromania mainly deal with personal issues in someone's life. This category includes adolescents who have committed crimes in the past. For example, 19% of adolescents suffering from pyromania have been charged with vandalism and 18% are non-violent sexual offenders. Other causes may include the seeking of attention from authorities or parents and resolving social issues such as bullying or lack of friends or siblings. Another cause may be that the patient is subconsciously seeking revenge for something that has occurred in the past. Individuals with pyromania have also been prominent in having antisocial traits. These include truancy, running away from home, and delinquency. Child and adolescent cases are usually associated with ADHD or adjustment disorders.

Most studied cases of pyromania occur in children and teenagers . There is a range of causes, but an understanding of the different motives and actions of fire setters can provide a platform for prevention. Common causes of pyromania can be broken down into two main groups: individual and environmental. This includes the complex understanding of factors such as individual temperament, parental psychopathology, and possible neurochemical predispositions. Many studies have shown that patients with pyromanias were in households without a father figure present.

Excessive computer use may result in, or occur with:

- Lack of face to face social interaction

- Computer vision syndrome

The identification of substance-induced versus independent psychiatric symptoms or disorders has important treatment implications and often constitutes a challenge in daily clinical practice. Similar patterns of comorbidity and risk factors in individuals with substance induced disorder and those with independent non-substance induced psychiatric symptoms suggest that the two conditions may share underlying etiologic factors.

Drug abuse, including alcohol and prescription drugs, can induce symptomatology which resembles mental illness, which can make it difficult to differentiate between substance induced psychiatric syndromes and pre-existing mental health problems. More often than not psychiatric disorders among drug or alcohol abusers disappear with prolonged abstinence. Substance induced psychiatric symptoms can occur both in the intoxicated state and also during the withdrawal state. In some cases these substance induced psychiatric disorders can persist long after detoxification, such as prolonged psychosis or depression after amphetamine or cocaine abuse. Abuse of hallucinogens can trigger delusional and other psychotic phenomena long after cessation of use and cannabis may trigger panic attacks during intoxication and with use it may cause a state similar to dysthymia. Severe anxiety and depression are commonly induced by sustained alcohol abuse which in most cases abates with prolonged abstinence. Even moderate sustained use of alcohol may increase anxiety and depression levels in some individuals. In most cases these drug induced psychiatric disorders fade away with prolonged abstinence. A protracted withdrawal syndrome can also occur with psychiatric and other symptoms persisting for months after cessation of use. Benzodiazepines are the most notable drug for inducing prolonged withdrawal effects with symptoms sometimes persisting for years after cessation of use.

Prospective epidemiological studies do not support the hypotheses that comorbidity of substance use disorders with other psychiatric illnesses is primarily a consequence of substance abuse or dependence or that increasing comorbidity is largely attributable to increasing use of substances. Yet emphasis is often on the effects of substances on the brain creating the impression that dual disorders are a natural consequence of these substances. However addictive drugs or exposure to gambling will not lead to addictive behaviors or drug dependence in most individuals but only in vulnerable ones, although, according to some researchers, neuroadaptation or regulation of neuronal plasticity, and molecular changes, may alter gene expression in some cases and subsequently lead to substance use disorders.

Research instruments are also often insufficiently sensitive to discriminate between independent, true dual pathology, and substance-induced symptoms. Structured instruments, as Global Appraisal of Individual Needs - Short Screener-GAIN-SS and Psychiatric Research Interview for Substance and Mental Disorders for DSM-IV-PRISM, have been developed to increase the diagnostic validity. While structured instruments can help organize diagnostic information, clinicians must still make judgments on the origin of symptoms.

Physical symptoms include:

- palpitations

- anorexia

- dry mouth

- insomnia

- thoracic/chest pressure

- respiratory difficulties

- epigastric mass

- headache

- a whole-body sensation of heat (distinct from heat intolerance, a symptom of hyperthyroidism)

Psychological symptoms include:

- being easily startled

- externalization of anger, also known in Korean as "bun" (분, 憤, "eruption of anger"), a Korean culture-related sentiment related to social unfairness

- generally sad mood

- frequent sighing

- a feeling of "eok-ul" (억울, 抑鬱, [feeling of] unfairness)

- being easily agitated

- feelings of guilt

- feelings of impending doom

Diagnosed patients may also have a medical history of prior major depressive disorder, dysthymic disorder, anxiety disorders, somatoform disorders, or adjustment disorder according to the "Diagnostic and Statistical Manual of Mental Disorders", fourth edition (DSM-IV) criteria.

Diagnosed patients are most likely to be middle-aged, post-menopausal women with low socio-economic status.

Computer addiction can be described as the excessive or compulsive use of the computer which persists despite serious negative consequences for personal, social, or occupational function. Another clear conceptualization is made by Block, who stated that "Conceptually, the diagnosis is a compulsive-impulsive spectrum disorder that involves online and/or offline computer usage and consists of at least three subtypes: excessive gaming, sexual preoccupations, and e-mail/text messaging". While it was expected that this new type of addiction would find a place under the compulsive disorders in the DSM-5, the current edition of the "Diagnostic and Statistical Manual of Mental Disorders", it is still counted as an unofficial disorder. The concept of computer addiction is broadly divided into two types, namely offline computer addiction and online computer addiction. The term offline computer addiction is normally used when speaking about excessive gaming behavior, which can be practiced both offline and online. Online computer addiction, also known as Internet addiction, gets more attention in general from scientific research than offline computer addiction, mainly because most cases of computer addiction are related to the excessive use of the Internet.

Although addiction is usually used to describe dependence on substances, addiction can also be used to describe pathological Internet use. Experts on Internet addiction have described this syndrome as an individual being intensely working on the Internet, prolonged use of the Internet, uncontrollable use of the Internet, unable to use the Internet with efficient time, not being interested in the outside world, not spending time with people from the outside world, and an increase in their loneliness and dejection. However, simply working long hours on the computer does not necessarily mean someone is addicted.

Hwabyeong or Hwabyung is a Korean somatization disorder, a mental illness which arises when people are unable to confront their anger as a result of conditions which they perceive to be unfair.

Hwabyung is a colloquial and somewhat inaccurate name, as it refers to the etiology of the disorder rather than its symptoms or apparent characteristics. Hwabyung is known as a culture-bound syndrome. The word hwabyung is composed of "hwa" (the Sino-Korean word for "fire" which can also contextually mean "anger") and "byung" (the Sino-Korean word for "syndrome" or "illness"). In South Korea, it may also be called "ulhwabyeong" (), literally "depression anger illness". In one survey, 4.1% of the general population in a rural area in Korea were reported as having hwabyung. Another survey shows that about 35% of Korean workers are affected by this condition at some time.

The main symptoms of paraphrenia are paranoid delusions and hallucinations. The delusions often involve the individual being the subject of persecution, although they can also be erotic, hypochondriacal, or grandiose in nature. The majority of hallucinations associated with paraphrenia are auditory, with 75% of patients reporting such an experience; however, visual, tactile, and olfactory hallucinations have also been reported. The paranoia and hallucinations can combine in the form of “threatening or accusatory voices coming from neighbouring houses [and] are frequently reported by the patients as disturbing and undeserved". Patients also present with a lack of symptoms commonly found in other mental disorders similar to paraphrenia. There is no significant deterioration of intellect, personality, or habits and patients often remain clean and mostly self-sufficient. Patients also remain oriented well in time and space.

Paraphrenia is different from schizophrenia because, while both disorders result in delusions and hallucinations, individuals with schizophrenia exhibit changes and deterioration of personality whereas individuals with paraphrenia maintain a well-preserved personality and affective response.

Sadistic personality disorder is a personality disorder involving which appeared in an appendix of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-III-R). The later versions of the DSM (DSM-IV, DSM-IV-TR and DSM-5) do not include it.

The words "sadism" and "sadist" are derived from Marquis de Sade.

Paraphrenia (from – beside, near + φρήν – intellect, mind) is a mental disorder characterized by an organized system of paranoid delusions with or without hallucinations (the positive symptoms of schizophrenia) without deterioration of intellect or personality (its negative symptom).

This disorder is also distinguished from schizophrenia by a lower hereditary occurrence, less premorbid maladjustment, and a slower rate of progression. Onset of symptoms generally occurs later in life, near the age of 60. The prevalence of the disorder among the elderly is between 0.1 and 4%

Paraphrenia is not included in the DSM-5; psychiatrists often diagnose patients presenting with paraphrenia as having atypical psychoses, delusional disorder, psychoses not otherwise specified, schizoaffective disorders, and persistent persecutory states of older adults. Recently, mental health professionals have also been classifying paraphrenia as very late-onset schizophrenia-like psychosis.

In the Russian psychiatric manuals paraphrenia (or paraphrenic syndrome) is the last stage of development of paranoid schizophrenia. "Systematized paraphrenia" (with systematized delusions i. e. delusions with complex logical structure) and "expansive-paranoid paraphrenia" (with expansive/grandiose delusions and persecutory delusions) are the variants of paranoid schizophrenia (). You see sometimes "systematized paraphrenia" with delusional disorder ().

Sadistic personality disorder has been found to occur frequently in unison with other personality disorders. Studies have also found that sadistic personality disorder is the personality disorder with the highest level of comorbidity to other types of psychopathological disorders. In contrast, sadism has also been found in patients who do not display any or other forms of psychopathic disorders. One personality disorder that is often found to occur alongside sadistic personality disorder is conduct disorder, not an adult disorder but one of childhood and adolescence. Studies have found other types of illnesses, such as alcoholism, to have a high rate of comorbidity with sadistic personality disorder.

Researchers have had some level of difficulty distinguishing sadistic personality disorder from other forms of personality disorders due to its high level of comorbidity with other disorders.

Feeding disorder has been divided into six further sub-types:

1. Feeding disorder of state regulation

2. Feeding disorder of reciprocity (neglect)

3. Infantile anorexia

4. Sensory food aversion

5. Feeding disorder associated with concurrent medical condition

6. Post-traumatic feeding disorder

The symptoms of autophobia vary by case. However, there are some symptoms that a multitude of people with this disease suffer from. An intense amount of apprehension and anxiety when you are alone or think about situations where you would be secluded is one of the most common indications that a person is autophobic. People with this disorder also commonly believe that there is an impending disaster waiting to occur whenever they are left alone. For this reason, autophobes go to extreme lengths to avoid being in isolation. However, people with this disease often do not need to be in "physical" isolation to feel abandoned. Autophobes will often be in a crowded area or group of people and feel as though they are completely secluded.

There has also been some connection to autophobia being diagnosed in people who also suffer from borderline personality disorders.

Below is a list of other symptoms that are sometimes associated with autophobia:

- Mental symptoms:

- Fear of fainting

- A disability to concentrate on anything other than the disease

- Fear of losing your mind

- Failure to think clearly

- Emotional symptoms:

- Stress over up-coming times and places where you may be alone

- Fear of being secluded

- Physical symptoms:

- Lightheadedness, dizziness

- Sweating

- Shaking

- Nausea

- Cold and hot flashes

- Numbness or tingling feelings

- Dry mouth

- Increased heart rate

A few of the medical and psychological conditions that have been known to be associated with this disorder include:

- Gastrointestinal motility disorders

- Oral-motor dysfunction

- Failure to thrive

- Prematurity

- Food allergies

- Sensory problems

- Reflux

- Feeding tube placement

A child that is suffering from malnutrition can have permanently stunted mental and physical development. Getting treatment early is essential and can prevent many of the complications. They can also develop further eating disorders later in life such as anorexia nervosa, or they could become a limited eater—though they could still be a healthy child they may become a picky eater.

Individuals with exploding head syndrome hear or experience loud imagined noises as they are falling asleep or waking up, have a strong, often frightened emotional reaction to the sound, and do not report significant pain; around 10% of people also experience visual disturbances like perceiving visual static, lightning, or flashes of light. Some people may also experience heat, strange feelings in their torso, or a feeling of electrical tinglings that ascends to the head before the auditory hallucinations occur. With the heightened arousal, people experience distress, confusion, myoclonic jerks, tachycardia, sweating, and the sensation that felt as if they had stopped breathing and had to make a deliberate effort to breathe again.

The pattern of the auditory hallucinations is variable. Some people report having a total of two or four attacks followed by a prolonged or total remission, having attacks over the course of a few weeks or months before the attacks spontaneously disappear, or the attacks may even recur irregularly every few days, weeks, or months for much of a lifetime.

Some individuals believe that EHS episodes are not natural events, but are the effects of directed energy weapons which create an auditory effect. Thus, EHS has been worked into conspiracy theories, but there is no scientific evidence that EHS has non-natural origins.