Excessive computer use may result in, or occur with:

- Lack of face to face social interaction

- Computer vision syndrome

Internet addiction disorder, more commonly called problematic Internet use (PIU), refers to excessive Internet use that interferes with daily life.

Internet addiction disorder is not listed in the latest DSM manual (DSM-5, 2013), which is commonly used by psychiatrists. Gambling disorder is the only behavioural (non-substance related) addiction included in DSM-5. However Internet gaming disorder is listed in Section III, Conditions for Further Study, as a disorder requiring further study.

Jerald J. Block, M.D. has argued that Internet addiction should be included as a disorder in the DSM-5. However, Block observed that diagnosis was complicated because 86% of study subjects showing symptoms also exhibited other diagnosable mental health disorders.

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.

Research by governments in Australia led to a universal definition for that country which appears to be the only research-based definition not to use diagnostic criteria: "Problem gambling is characterized by many difficulties in limiting money and/or time spent on gambling which leads to adverse consequences for the gambler, others, or for the community." The University of Maryland Medical Center defines pathological gambling as "being unable to resist impulses to gamble, which can lead to severe personal or social consequences".

Most other definitions of problem gambling can usually be simplified to any gambling that causes harm to the gambler or someone else in any way; however, these definitions are usually coupled with descriptions of the type of harm or the use of diagnostic criteria. The "DSM-V" has since reclassified pathological gambling as "gambling disorder" and has listed the disorder under substance-related and addictive disorders rather than impulse-control disorders. This is due to the symptomatology of the disorder resembling an addiction not dissimilar to that of substance-abuse. There are both environmental and genetic factors that can influence on gambler and cause some type of addiction. In order to be diagnosed, an individual must have at least four of the following symptoms in a 12-month period:

- Needs to gamble with increasing amounts of money in order to achieve the desired excitement

- Is restless or irritable when attempting to cut down or stop gambling

- Has made repeated unsuccessful efforts to control, cut back, or stop gambling

- Is often preoccupied with gambling (e.g., having persistent thoughts of reliving past gambling experiences, handicapping or planning the next venture, thinking of ways to get money with which to gamble)

- Often gambles when feeling distressed (e.g., helpless, guilty, anxious, depressed)

- After losing money gambling, often returns another day to get even ("chasing" one's losses)

- Lies to conceal the extent of involvement with gambling

- Has jeopardized or lost a significant relationship, job, education or career opportunity because of gambling

- Relies on others to provide money to relieve desperate financial situations caused by gambling

The DSM definition of addiction can be boiled down to compulsive use of a substance (or engagement in an activity) despite ongoing negative consequences. The medical community makes a distinction between physical dependence (characterized by symptoms of physical withdrawal symptoms, like tremors and sweating) and psychological dependence (emotional-motivational withdrawal symptoms). Physical dependence is simply needing a substance to function. Humans are all physically dependent upon oxygen, food and water. A drug can cause physical dependence and not psychological dependence (for example, some blood pressure medications, which can produce fatal withdrawal symptoms if not tapered) and some can cause psychological dependence without physical dependence (the withdrawal symptoms associated with cocaine are all psychological, there is no associated vomiting or diarrhea as there is with opiate withdrawal).

There are several different screening tools that have been validated for use with adolescents such as the CRAFFT and adults such as the CAGE.

Psychological dependence is a form of dependence that involves emotional–motivational withdrawal symptoms (e.g., a state of unease or dissatisfaction, a reduced capacity to experience pleasure, or anxiety) upon cessation of drug use or engagement in certain behaviors. Physical and psychological dependence are sometimes classified as a facet or component of addiction, such as in the DSM-IV-TR; however, some drugs which produce dependence syndromes do not produce addiction, and vice versa, in humans. Addiction and psychological dependence are both mediated through reinforcement, a form of operant conditioning, but are associated with different forms of reinforcement. Addiction is a compulsion for rewarding stimuli that is mediated through positive reinforcement. Psychological dependence, which is mediated through negative reinforcement, involves a desire to use a drug or perform a behavior to avoid the unpleasant withdrawal syndrome that results from cessation of exposure to it.

Psychological dependence develops through consistent and frequent exposure to a stimulus. Behaviors which can produce observable psychological withdrawal symptoms (i.e., cause psychological dependence) include physical exercise, shopping, sex and self-stimulation using pornography, and eating food with high sugar or fat content, among others. Behavioral therapy is typically employed to help individuals overcome psychological dependence upon drugs or maladaptive behaviors that produce psychological dependence.

Physical dependence on a substance is defined by the appearance of characteristic physical withdrawal symptoms when the substance is suddenly discontinued. Opiates, benzodiazepines, barbiturates, alcohol and nicotine induce physical dependence. On the other hand, some categories of substances share this property and are still not considered addictive: cortisone, beta blockers and most antidepressants are examples.

Some substances induce physical dependence or physiological tolerance - but not addiction — for example many laxatives, which are not psychoactive; nasal decongestants, which can cause rebound congestion if used for more than a few days in a row; and some antidepressants, most notably venlafaxine, paroxetine and sertraline, as they have quite short half-lives, so stopping them abruptly causes a more rapid change in the neurotransmitter balance in the brain than many other antidepressants. Many non-addictive prescription drugs should not be suddenly stopped, so a doctor should be consulted before abruptly discontinuing them.

The speed with which a given individual becomes addicted to various substances varies with the substance, the frequency of use, the means of ingestion, the intensity of pleasure or euphoria, and the individual's genetic and psychological susceptibility. Some people may exhibit alcoholic tendencies from the moment of first intoxication, while most people can drink socially without ever becoming addicted. Opioid dependent individuals have different responses to even low doses of opioids than the majority of people, although this may be due to a variety of other factors, as opioid use heavily stimulates pleasure-inducing neurotransmitters in the brain. Nonetheless, because of these variations, in addition to the adoption and twin studies that have been well replicated, much of the medical community is satisfied that addiction is in part genetically moderated. That is, one's genetic makeup may regulate how susceptible one is to a substance and how easily one may become attached to a pleasurable routine.

Eating disorders are complicated pathological mental illnesses and thus are not the same as addictions described in this article. Eating disorders, which some argue are not addictions at all, are driven by a multitude of factors, most of which are highly different from the factors behind addictions described in this article. It has been reported, however, that patients with eating disorders can successfully be treated with the same non-pharmacological protocols used in patients with chemical addiction disorders.

Gambling is another potentially addictive behavior with some biological overlap. Conversely gambling urges have emerged with the administration of Mirapex (pramipexole), a dopamine agonist.

The obsolete term physical addiction is deprecated, because of its connotations. In modern pain management with opioids physical dependence is nearly universal. High-quality, long-term studies are needed to better delineate the risks and benefits of chronic opiate use.

Mobile phone overuse (mobile-phone addiction or problem mobile phone use) is a dependence syndrome seen among certain mobile phone users. Some mobile phone users exhibit problematic behaviors related to substance use disorders. These behaviors can include preoccupation with mobile communication, excessive money or time spent on mobile phones, use of mobile phones in socially or physically inappropriate situations such as driving an automobile. Increased use can also lead to increased time on mobile communication, adverse effects on relationships, and anxiety if separated from a mobile phone or sufficient signal.

Behavioral addiction is a form of addiction that involves a compulsion to engage in a rewarding non-drug-related behavior – sometimes called a natural reward – despite any negative consequences to the person's physical, mental, social or financial well-being. A gene transcription factor known as ΔFosB has been identified as a necessary common factor involved in both behavioral and drug addictions, which are associated with the same set of neural adaptations in the reward system.

Shopping addiction is defined as the deficiency of impulse control which appears as the eagerness for constantly making new purchases of unnecessary or superfluous things. It is a concept similar to "compulsive buying disorder" and "oniomania", although these terms usually have a more clinical approach, related to a psychological individual disorder of impulse control. The phrase “shopping addiction” usually has a more psychosocial perspective . or it is placed among drug-free addictions like the addiction to gambling, Internet, or video-games.

Problem gambling (or ludomania, but usually referred to as "gambling addiction" or "compulsive gambling") is an urge to gamble continuously despite harmful negative consequences or a desire to stop. Problem gambling is often defined by whether harm is experienced by the gambler or others, rather than by the gambler's behaviour. Severe problem gambling may be diagnosed as clinical pathological gambling if the gambler meets certain criteria. Pathological gambling is a common disorder that is associated with both social and family costs.

The "DSM-5" has re-classified the condition as an addictive disorder, with sufferers exhibiting many similarities to those who have substance addictions.

The term "gambling addiction" has long been used in the recovery movement. Pathological gambling was long considered by the American Psychiatric Association to be an impulse control disorder rather than an addiction. However, data suggest a closer relationship between pathological gambling and substance use disorders than exists between PG and obsessive-compulsive disorder, largely because the behaviors in problem gambling and most primary substance use disorders ("i.e.", those not resulting from a desire to "self-medicate" for another condition such as depression) seek to activate the brain's reward mechanisms while the behaviors characterizing obsessive-compulsive disorder are prompted by overactive and misplaced signals from the brain's fear mechanisms.

Problem gambling is an addictive behavior with a high comorbidity with alcohol problems. Comorbidity is the presence of one or more diseases or disorders co-occurring with each other. A common feature shared by people who suffer from gambling addiction is impulsivity.

Experts describe the spectrum of behaviors designated as addictive in terms of five interrelated concepts: patterns, habits, compulsions, impulse control disorders, and physical addiction.

Codependency is a type of dysfunctional helping relationship where one person supports or enables another person's drug addiction, alcoholism, gambling addiction, poor mental health, immaturity, irresponsibility, or under-achievement. Among the core characteristics of codependency, the most common theme is an excessive reliance on other people for approval and a sense of identity.

Given its grassroots origin, the precise definition of codependency varies based on the source but can be generally characterized as a subclinical and situational or episodic behavior similar to that of dependent personality disorder. In its broadest definition, a codependent is someone who cannot function from their innate self and whose thinking and behavior is instead organized around another person, or even a process, or substance. In this context, people who are addicted to a substance, like drugs, or a process, like gambling or sex, can also be considered codependent. In its most narrow definition, it requires one person to be physically or psychologically addicted, such as to heroin, and the second person to be psychologically dependent on that behavior. Some users of the codependency concept use the word as an alternative to using the concept of dysfunctional families, without statements that classify it as a disease.

Codependency does not refer to all caring behavior or feelings, but only those that are excessive to an unhealthy degree. One of the distinctions is that healthy empathy and caregiving is motivated by conscious choice; whereas for codependents, their actions are compulsive, and they usually aren't able to weigh in the consequences of them or their own needs that they're sacrificing. Some scholars and treatment providers feel that codependency is an overresponsibility and that overresponsibility needs to be understood as a positive impulse gone awry. Responsibility for relationships with others needs to coexist with responsibility to self.

Codependency has been referred to as the disease of a lost self. Codependent relationships are marked by intimacy problems, dependency, control (including caretaking) denial, dysfunctional communication and boundaries, and high reactivity. Often, there is imbalance, so one person is abusive or in control or supports or enables another person's addiction, poor mental health, immaturity, irresponsibility, or under-achievement. Some codependents often find themselves in relationships where their primary role is that of rescuer, supporter, and confidante. These helper types are often dependent on the other person's poor functioning to satisfy their own emotional needs. Many codependents place a lower priority on their own needs, while being excessively preoccupied with the needs of others. Codependency can occur in any type of relationship, including family, work, friendship, and also romantic, peer or community relationships.

Commonly cited symptoms of codependency are:

- intense and unstable interpersonal relationships

- inability to tolerate being alone, accompanied by frantic efforts to avoid being alone

- chronic feelings of boredom and emptiness

- subordinating one's own needs to those of the person with whom one is involved

- overwhelming desire for acceptance and affection

- perfectionism

- over-controlling

- external referencing

- dishonesty and denial

- manipulation

- lack of trust

- low self-worth.

Compulsions and addictions are intertwined and reward is one major distinction between an addiction and a compulsion (as it is experienced in obsessive-compulsive disorder). An addiction is, by definition, a form of compulsion, and both addictions and compulsions involve operant reinforcement; however, in addiction, the desire and motivation to use a substance or engage in a behavior arises because it is rewarding (i.e., the compulsions that occur in addiction develop through positive reinforcement). In contrast, someone who experiences a compulsion as part of obsessive-compulsive disorder may not perceive anything rewarding from acting on the compulsion. Often, it is a way of dealing with the obsessive part of the disorder, resulting in a feeling of relief (i.e., compulsions may also arise through negative reinforcement).

Deep brain stimulation to the nucleus accumbens, a region in the brain involved heavily in addiction and reinforcement learning, has proven to be an effective treatment of obsessive compulsive disorder.

The terms compulsive shopping, compulsive buying, and compulsive spending are often used interchangeably, but the behaviors they represent are in fact distinct. (Nataraajan and Goff 1992) One may buy without shopping, and certainly shop without buying: of compulsive shoppers, some 30% described the act of buying itself as providing a buzz, irrespective of the goods purchased.

CBD is frequently comorbid with mood, anxiety, substance abuse and eating disorders. People who score highly on compulsive buying scales tend to understand their feelings poorly and have low tolerance for unpleasant psychological states such as bad moods. Onset of CBD occurs in the late teens and early twenties and is generally chronic. CBD is similar to, but distinguished from, OCD hoarding and mania. Compulsive buying is not limited to people who spend beyond their means; it also includes people who spend an inordinate amount of time shopping or who chronically think about buying things but never purchase them. Promising treatments for CBD include medication such as selective serotonin reuptake inhibitors (SSRIs), and support groups such as Debtors Anonymous.

Five indicators of exercise addiction are:

1. An increase in exercise that may be labeled as detrimental, or becomes harmful.

2. A desire to experience euphoria; exercise may be increased as tolerance of the euphoric state increases.

3. Not participating in physical activity will cause in one's daily life.

4. Severe withdrawal symptoms following exercise deprivation including anxiety, restlessness, depression, guilt, tension, discomfort, loss of appetite, sleeplessness, and headaches.

5. Exercising through trauma and despite physical injuries.

Key differences between healthy and addictive levels of exercise include the presence of withdrawal symptoms when exercise is stopped as well as the addictive properties exercise may have leading to a dependence on exercise.

Cannabis use is associated with comorbid mental health problems, such as mood and anxiety disorders, and discontinuing cannabis use is difficult for some users. Psychiatric comorbidities are often present in dependent cannabis users including a range of personality disorders.

Cannabis withdrawal symptoms can occur in one half of patients in treatment for cannabis use disorders. These symptoms include dysphoria (anxiety, irritability, depression, restlessness), disturbed sleep, gastrointestinal symptoms, and decreased appetite. Most symptoms begin during the first week of abstinence and resolve after a few weeks.

According to the National Cannabis Prevention and Information Centre in Australia, a sign of cannabis dependence is that an individual spends noticeably more time than the average recreational user recovering from the use of or obtaining cannabis. For some, using cannabis becomes a substantial and disruptive part of an individual's life and he or she may exhibit difficulties in meeting personal obligations or participating in important life activities, preferring to use cannabis instead. People who are cannabis dependent have the inability to stop or decrease using cannabis on their own.

An addictive personality refers to a particular set of personality traits that make an individual predisposed to developing addictions. This hypothesis states that there may be common personality traits observable in people suffering from addiction. Alan R. Lang of Florida State University, author of an addiction study prepared for the United States National Academy of Sciences, said, "If we can better identify the personality factors, they can help us devise better treatment and can open up new strategies to intervene and break the patterns of addiction."

A concrete classification of exercise addiction has proven to be difficult due to the lack of a specific and widely accepted diagnostic model. Most interpretations of addiction have traditionally been limited to drugs and alcohol, which makes it even more difficult to identify addictive tendencies in exercise. While excessive exercise is the overarching theme with exercise addiction, the term also includes a variety of symptoms like withdrawal, "exercise buzz", and impaired physical function. Excessive exercise has been classified in different ways; sometimes as an addiction and sometimes as a more general compulsive behavior. Psychiatric case studies have shown that exaggerated exercise could lead to negligence of work and family life. With an addiction, individuals become "hooked" to the feeling of euphoria and pleasure that exercise provides. This pleasure keeps the individual from stopping and leads to excessive exercise. With a compulsion people often do not necessarily enjoy repeating certain tasks, as they may feel like performing it will fulfill a duty that is required of them. There are many opinions on whether concrete diagnostic criteria should be created for this type of addiction. Some say preoccupation with exercise that causes significant impairment in a person's life, not due to another disorder, may be enough criteria to label this disorder. Others say there is not enough information about exercise addiction to develop diagnostic criteria. , the term "excessive exercise" continues to be used while the "exercise addiction" model continues to be debated.

Three main types of disorders are associated with excessive exercise:

1. Anorexia athletica (obligatory exercise) - When an individual feels compelled to exercise beyond the point of benefitting one's body. Individuals will participate in athletic activities regardless of pain, injury, illness, etc., and will try to arrange their lives in order to maximize workout time.

2. Exercise bulimia - When an individual has binge eating sessions that are followed by periods of high-intensity exercise.

3. Body dysmorphic disorder - When an individual is obsessed with parts of their body and perceive them to be different or odd. These individuals will create highly regimented routines in order to improve their perception of the "flawed" body part.

Since people buying more than they need is usual and accepted, even the most excessive behaviour takes a long time before being considered pathological. Shopping addiction generally manifests between 20–30 years old,

but is not usually detected until several years after, when the addiction has led the person to ruin and bankrupt.

There are usually two stages in coping with the problem. First, people around the addict or the health or social services detect the problem and try to treat it. When, because of the seriousness of the case, it is not possible to solve it in this way, specialised professionals, such as psychologist or psychiatrics, take part. The diagnosis and evaluation of shopping addiction is based on the analysis of confirmed behaviours and their consequences. Specific tests or questionnaires, as the FACC-II (Questionnaire on the psychological aspects of consumer addiction, debt and personal spending habits) are also used. These specific questionnaires or tests are useful in the diagnosis and evaluation of shopping addiction problems, and to drive the therapies in a proper way. FACC-II is one of the most specific and widest. The Edwards Scale is another approach which measures the tendency to compulsively buy. All these resources, as well as personal interviews of the addict and people who surround them, reports and other documents, enable knowledge of when people buy, what they buy and the methods of payment used.

Signs and symptoms of opioid intoxication include:

- Decreased perception of pain

- Euphoria

- Confusion

- Desire to sleep

- Nausea

- Constipation

- Miosis