Substance use and dependence

Among people who use psychoactive substances, some use them in large quantities, often enough, and for a long time before becoming dependent. There is no simple definition of addiction. The concepts of tolerance, mental dependence, and physical dependence help in defining the term addiction.

Tolerance is considered to be the need to progressively increase the dose of a drug in order to obtain the effect previously achieved with lower doses.

Psychological dependence involves the experience of pleasure and the desire to use the substance again or to avoid unpleasant sensations in the absence of the substance. This expectation of an effect is a powerful factor in chronic substance use and for some substances may be the only obvious factor associated with craving and apparently compulsive use. The strong desire and urge to use the substance leads to use in greater quantities and for a longer period of time than intended at the onset of use. Psychological dependence also involves neglecting social, occupational, or recreational activities because of substance use or continuing to use despite the knowledge that existing physical or mental problems are likely to be related to or worsened by substance use. Substances that cause psychological dependence often have one or more of the following effects: decreased anxiety and tension; elevated mood, euphoria, and other mood changes that are pleasurable to the user; increased mental and physical alertness; sensory disturbances; changes in behavior. Drugs that cause predominantly psychological dependence include marijuana, amphetamines, 3,4-methylenedioxymethamphetamine (MDMA), and hallucinogens such as lysergic acid diethylamide (LSD), mescaline, and psilocybin.

Physical dependence is manifested by withdrawal syndrome (abstinence), when severe somatic disorders are observed as a result of stopping the use of a substance or when its effects are neutralized by a specific antagonist that displaces the agonist from the connections with cellular receptors. Substances that cause severe physical dependence include heroin, alcohol, and cocaine.

Addiction, a concept without a consistent, universally accepted definition, is used to describe compulsive use and total involvement in the process of using a substance, including spending increasing amounts of time acquiring the drug, using it, and recovering from the drug's narcotic effects; it can also occur in the absence of physical dependence. Addiction implies the risk of harmful consequences and the need to stop using the substance, regardless of whether the patient understands or agrees to this.

Substance abuse is defined only by social disapproval. Abuse may include experimental or recreational use of a psychoactive substance, often an illegal substance; unauthorized or illegal use of psychoactive substances that results in complications or the development of certain symptoms; use of the drug initially for the two above reasons but later because of the development of dependence and the need to continue taking it at least partly to prevent withdrawal symptoms. Use of illegal drugs does not imply dependence, although illegality is a criterion for abuse. Conversely, use of legal substances such as alcohol can lead to dependence and abuse. Abuse of prescribed and illegal drugs occurs across socioeconomic groups, among people with higher education and high professional status.

Recreational drug use is increasing and becoming part of Western culture, although it is generally frowned upon. Some users have no obvious complications, and use the drugs sporadically and in relatively small doses, which prevents toxic effects, tolerance, and physical dependence. Many recreational drugs (e.g., unrefined opium, marijuana, caffeine, hallucinogenic mushrooms, coca leaves) are natural, including alcohol. They contain a mixture of psychoactive components in relatively low concentrations, rather than being isolated psychoactive substances. Recreational drugs are usually taken orally or inhaled. Injecting these drugs makes it difficult to control the desired and unwanted effects. Recreational use is often ritualized, follows specific rules, and is rarely done alone. Most of these drugs are stimulants or hallucinogens, designed to produce a "high" or altered state of consciousness rather than to relieve mental distress; depressants are difficult to use in such a controlled manner.

Intoxication is manifested by a reversible, substance-specific syndrome of mental and behavioral changes that may include cognitive impairment, decreased critical thinking, impaired physical and social functioning, mood instability, and aggression.

In the United States, the Comprehensive Drug Abuse Prevention and Control Act of 1970 and its subsequent amendments require the pharmaceutical industry to maintain special storage conditions and strict accountability for certain classes of drugs. Controlled substances are divided into five schedules (or classes) based on their abuse potential, appropriate medical use, and adequate safety for use under medical supervision. Schedule I drugs have a high abuse potential, potential for off-label use, and a lack of adequate safety for use. Schedule V drugs are unlikely to be abused. This scheduling classification determines how the drug is controlled. Schedule I drugs may only be used under legally approved research conditions. Schedules II-IV drugs must be prescribed by physicians who are federally licensed by the Drug Enforcement Administration (DEA). Some Schedule V drugs are prescribed without a prescription. State schedules may differ from the federal schedules.

The Cause of Substance Abuse

Commonly used psychoactive substances vary in their addictive potential. The development of addiction to psychoactive substances is complex and not well understood. It is influenced by the properties of the substance used; the predisposing physical characteristics of the user (likely including genetic predisposition), personality, socioeconomic class, and cultural and social environment. The psychology of the individual and the availability of the drug determine the choice of psychoactive substance and, at least initially, the patterns and frequency of use.

The progression from experimental to chronic use and then to dependence is only partially understood. Factors that lead to increased use and dependence or addiction include peer or group influence, emotional distress that is symptomatically relieved by the specific effects of the drug, sadness, social isolation, and external stress (especially when accompanied by a sense of the importance of effective change or goal attainment). Physicians may inadvertently contribute to substance abuse by over-prescribing to stressed patients or by being influenced by manipulative patients. Many social factors and the media may contribute to the assumption that psychoactive substances safely relieve stress or provide pleasure. Simply put, the outcome of substance use depends on the interactions between the drug, the user, and the environment.

There are only minor differences in the biochemical, pharmacokinetic, and physical responses of people who have developed addiction or dependence and those who have not, although there is an intense search for these differences. However, there are exceptions: non-drinking relatives of alcoholics have a reduced response to alcohol. Because of their higher tolerance, they need to drink more to achieve the desired effect.

The neurological substrate of the reinforcement reflex (the tendency to seek psychoactive substances and other stimuli) has been studied in animal models. These studies have shown that self-administration of drugs such as opioids, cocaine, amphetamines, nicotine, and benzodiazepines (anxiolytics) is associated with increased dopaminergic transmission in specific areas of the midbrain and cortex. These data support the existence of brain pathways that include dopamine in the mammalian brain. However, evidence that hallucinogens and cannabinoids activate this system is insufficient; not everyone who receives such a “reward” develops addiction or dependence.

The addictive personality has been described by many behavioral scientists, but there is little evidence to support its existence. Some experts describe addicts as escapist, unable to face reality, running away from it. Others describe addicts as having schizoid features such as fearfulness, withdrawal from others, feelings of depression, and a history of suicidal and self-harming behavior. Addicts are also often described as dependent, easily attached in relationships, and often displaying intense, unconscious anger and immature sexuality. However, before an addictive personality develops, the person is usually not prone to the deviant, pleasure-seeking, irresponsible behavior that characterizes addicts. Physicians, patients, and society often perceive substance abuse in the context of dysfunctional lives or life episodes, judging only the substance rather than the addict's psychological characteristics. Sometimes addicts justify the use of psychoactive substances by the need for temporary relief from anxiety and depression caused by a crisis, difficulties at work, family problems. Many addicts abuse alcohol and other psychoactive substances at the same time, they may have repeated hospitalizations due to overdoses, side effects, and withdrawal symptoms.