Addiction is a neuropsychological disorder characterized by a persistent and intense urge to use a drug or engage in a behavior that produces natural reward, despite substantial harm and other negative consequences.

Repetitive drug use can alter brain function in synapses similar to natural rewards like food or falling in love[1] in ways that perpetuate craving and weakens self-control for people with pre-existing vulnerabilities.

[7] Classic signs of addiction include compulsive engagement in rewarding stimuli, preoccupation with substances or behavior, and continued use despite negative consequences.

Habits and patterns associated with addiction are typically characterized by immediate gratification (short-term reward),[8][9] coupled with delayed deleterious effects (long-term costs).

[15] A common use of "addiction" in medicine is for neuropsychological symptoms denoting pervasive/excessive and intense urges to engage in a category of behavioral compulsions or impulses towards sensory rewards (e.g., alcohol, betel quid, drugs, sex, gambling, video gaming).

[21][15][19][20] The DSM-5 classifies addiction the most severe stage of substance use disorder, due to significant loss of control and the presence of compulsive behaviours despite the desire to stop.

[31] Substances involved with drug addiction include alcohol, nicotine, marijuana, opioids, cocaine, amphetamines, and even foods with high fat and sugar content.

[42][12][37] It was developed in 2009 at Yale University on the hypothesis that foods high in fat, sugar, and salt have addictive-like effects which contribute to problematic eating habits.

[9][38][39] Preclinical evidence has demonstrated that marked increases in the expression of ΔFosB through repetitive and excessive exposure to a natural reward induces the same behavioral effects and neuroplasticity as occurs in a drug addiction.

[56] Risk factors for gambling addictions include antisocial behavior, impulsive personality,[37] male sex, sensation seeking,[57] substance use, and young age.

Gambling addiction has been associated with some personality traits, including: harm avoidance, low self direction, decision making and planning insufficiencies, impulsivity, as well as sensation seeking individuals.

[87] The Adverse Childhood Experiences Study by the Centers for Disease Control and Prevention has shown a strong dose–response relationship between ACEs and numerous health, social, and behavioral problems throughout a person's lifespan, including substance use disorder.

[108] This pathway towards addiction that is opened through stressful experiences during childhood can be avoided by a change in environmental factors throughout an individual's life and opportunities of professional help.

[38][47][48] This phenomenon is notable since, in humans, a dopamine dysregulation syndrome, characterized by drug-induced compulsive engagement in natural rewards (specifically, sexual activity, shopping, and gambling), has been observed in some individuals taking dopaminergic medications.

Symptoms of withdrawal generally include but are not limited to body aches, anxiety, irritability, intense cravings for the substance, dysphoria, nausea, hallucinations, headaches, cold sweats, tremors, and seizures.

[34] Based on representative samples of the US youth population in 2011[update], the lifetime prevalence[note 7] of addictions to alcohol and illicit drugs has been estimated to be approximately 8% and 2–3% respectively.

[46] According to a 2017 poll conducted by the Pew Research Center, almost half of US adults know a family member or close friend who has struggled with a drug addiction at some point in their life.

[194] An article in The Washington Post stated that "America's largest drug companies flooded the country with pain pills from 2006 through 2012, even when it became apparent that they were fueling addiction and overdoses."

In the United Nations Office on Drugs and Crime report,[199] although South America produced 3% of the world's morphine and heroin and 0.01% of its opium, prevalence of use is uneven.

According to the Inter-American Commission on Drug Abuse Control, consumption of heroin is low in most Latin American countries, although Colombia is the area's largest opium producer.

[215] During the course of treatment, by examining and comparing artwork created at different times, art therapists can be helpful in identifying and diagnosing issues, as well as charting the extent or direction of improvement as a person detoxifies.

In turn, the art therapy component of the programme fostered stronger self-awareness, exploration, and externalization of repressed and unconscious emotions of clients, promoting the development of a more integrated 'authentic self'.

[218][214] Despite the large number of randomized control trials, clinical control trials, and anecdotal evidence supporting the effectiveness of art therapies for use in addiction treatment, a systematic review conducted in 2018 could not find enough evidence on visual art, drama, dance and movement therapy, or 'arts in health' methodologies to confirm their effectiveness as interventions for reducing substance misuse.

[223] Stigma can lead to feelings of shame that can prevent people with substance use disorders from seeking help and interfere with provision of harm reduction services.

[229] Quantitative and qualitative data was recorded to measure engagement, and the student artists were interviewed, which revealed a change in perspective and understanding, as well as greater appreciation of diverse experiences.

Over time, as clients progressed through the program, their stories became more complex and detailed, including their drug abuse and recovery efforts, more skeptical positions towards treatment began to emerge.

[233] Due to higher medication consumption, social isolation, financial worries, and other factors, older adults are particularly vulnerable to substance use problems.

[235] A study conducted in 2009 in the Republic of Moldova looked into the social dynamics of initiating injection drug usage by examining 42 audio-recorded, semi-structured interviews with present and former injectors.

[244] The seminal publication "Taking care of business", by Edward Preble and John J. Casey, documented the daily lives of New York street-based intravenous heroin users in rich detail, providing unique insight into the dynamic social worlds and activities that surrounded their drug use.

[244] Emerging in the early 1980s, the critical medical anthropology model was introduced, and as Merrill Singer offers 'was applied quickly to the analysis of drug use'.