Substance dependence in the context of "Smoking cessation"

Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic alcohol use has been mentioned in the earliest historical records. The World Health Organization (WHO) estimated there were 283 million people with alcohol use disorders worldwide as of 2016. The term alcoholism was first coined in 1852, but alcoholism and alcoholic are considered stigmatizing and likely to discourage seeking treatment, so diagnostic terms such as alcohol use disorder and alcohol dependence are often used instead in a clinical context. Other terms, some slurs and some informal, have been used to refer to people affected by alcoholism such as tippler, sot, drunk, drunkard, dipsomaniac and souse.

Alcohol is addictive, and heavy long-term use results in many negative health and social consequences. It can damage all organ systems, but especially affects the brain, heart, liver, pancreas, and immune system. Heavy usage can result in trouble sleeping, and severe cognitive issues like dementia, brain damage, or Wernicke–Korsakoff syndrome. Physical effects include irregular heartbeat, impaired immune response, cirrhosis, increased cancer risk, and severe withdrawal symptoms if stopped suddenly.

Drug injection is a method of introducing a drug into the bloodstream via a hollow hypodermic needle, which is pierced through the skin into the body (usually intravenously, but also at an intramuscular or subcutaneous, location). Intravenous therapy, a form of drug injection, is universally practiced in modernized medical care. As of 2004, there were 13.2 million people worldwide who self-administered injection drugs outside of medical supervision, of which 22% are from developed countries.

A wide variety of drugs are injected, often opioids: these may include legally prescribed medicines and medication such as morphine, as well as stronger compounds often favored in recreational drug use, which are often illegal. Ketamine administered intravenously in clinical settings has become more common. Although there are various methods of taking drugs, injection is favoured by some people as the full effects of the drug are experienced very quickly, typically in five to ten seconds. It also bypasses first-pass metabolism in the liver, resulting in higher bioavailability and efficiency for many drugs (such as morphine or diacetylmorphine/heroin; roughly two-thirds of which is destroyed in the liver when consumed orally) than oral ingestion would. The effect is that the person gets a stronger (yet shorter-acting) effect from the same amount of the drug. Drug injection is therefore often related to substance dependence.

Alcohol, sometimes referred to by the chemical name ethanol, is the active ingredient in alcoholic drinks such as beer, wine, and distilled spirits (hard liquor). Alcohol is a central nervous system (CNS) depressant, decreasing electrical activity of neurons in the brain, which causes the characteristic effects of alcohol intoxication ("drunkenness"). Among other effects, alcohol produces euphoria, decreased anxiety, increased sociability, sedation, and impairment of cognitive, memory, motor, and sensory function.

Alcohol has a variety of adverse effects. Short-term adverse effects include generalized impairment of neurocognitive function, dizziness, nausea, vomiting, and symptoms of hangover. Alcohol is addictive and can result in alcohol use disorder, dependence, and withdrawal upon cessation. The long-term effects of alcohol are considered to be a major global public health issue and include liver disease, hepatitis, cardiovascular disease (e.g., cardiomyopathy), polyneuropathy, alcoholic hallucinosis, long-term impact on the brain (e.g., brain damage, dementia, and Marchiafava–Bignami disease), and cancers; alcohol and some of its metabolites (such as acetaldehyde) are IARC group 1 carcinogens. The adverse effects of alcohol on health are most significant when it is used in excessive quantities or with heavy frequency. However, in 2023, the World Health Organization published a statement in The Lancet Public Health that concluded, "no safe amount of alcohol consumption for cancers and health can be established." In high amounts, alcohol may cause loss of consciousness or, in severe cases, death. Many governmental agencies and organizations issue alcohol consumption recommendations.

Drug withdrawal, drug withdrawal syndrome, or substance withdrawal syndrome is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of pharmaceutical or recreational drugs.

In order for the symptoms of withdrawal to occur, one must have first developed a form of drug dependence. This may occur as physical dependence, psychological dependence, or both. Drug dependence develops from consuming one or more substances over a period of time.

Alcohol dependence is a previous (DSM-IV and ICD-10) psychiatric diagnosis in which an individual is physically or psychologically dependent upon alcohol (also chemically known as ethanol).

In 2013, it was reclassified as alcohol use disorder in DSM-5, which combined alcohol dependence and alcohol abuse into this diagnosis.

Nicotine dependence is a state of substance dependence on nicotine. It is a chronic, relapsing disease characterized by a compulsive craving to use the drug despite social consequences, loss of control over drug intake, and the emergence of withdrawal symptoms. Tolerance is another component of drug dependence. Nicotine dependence develops over time as an individual continues to use nicotine. While cigarettes are the most commonly used tobacco product, all forms of tobacco use—including smokeless tobacco and e-cigarette use—can cause dependence. Nicotine dependence is a serious public health problem because it leads to continued tobacco use and the associated negative health effects. Tobacco use is one of the leading preventable causes of death worldwide, causing more than 8 million deaths per year and killing half of its users who do not quit. Current smokers are estimated to die an average of 10 years earlier than non-smokers.

According to the World Health Organization, "Greater nicotine dependence has been shown to be associated with lower motivation to quit, difficulty in trying to quit, and failure to quit, as well as with smoking the first cigarette earlier in the day and smoking more cigarettes per day." The WHO estimates that there were 1.24 billion tobacco users globally in 2022, with the number projected to decline to 1.20 billion in 2025. Of the 34 million smokers in the United States in 2018, 74.6% smoked every day, indicating the potential for some level of nicotine dependence. There is an increased incidence of nicotine dependence in individuals with psychiatric disorders, such as anxiety disorders and substance use disorders.

The disease model of addiction describes an addiction as a disease with genetic, biological, neurological or environmental origin. The traditional medical model of disease requires only an abnormal condition causing distress, discomfort or dysfunction to an affected individual. The contemporary medical model partly attributes addiction to changes in the brain's mesolimbic pathway. The model also considers these diseases as a result of other biological, psychological or sociological entities, despite an incomplete understanding of their mechanisms. The common biomolecular mechanisms underlying addiction – CREB and ΔFosB – were reviewed by Eric J. Nestler in a 2013 review. Genetics and mental disorders may precipitate the severity of a drug addiction. It is estimated that 50% of healthy individuals developing an addiction can trace the cause to genetic factors.