Addiction and Habituation Health Article

ADDICTION AND HABITUATION

Although there is no definition of "addiction" that is universally accepted, in general, addiction refers to a physiological and psychological dependency on a drug. While some drugs of abuse induce physiological addiction, others do not. Alternatively, some drugs that are physiologically addictive generally are not abused (e.g., caffeine). Tolerance to drug effects, and withdrawal symptoms upon abrupt cessation of use, which develop over time, are characteristic features of physiological addiction. "Habituation" is the term used to refer to psychological dependence on a drug. Some drugs of abuse are highly rewarding because of their influence on reinforcing neurobiological processes, but they do not necessarily result in "tissue" related withdrawal symptoms. Cessation of such drugs may lead primarily to subjective craving due to previous drug conditioning (perhaps true of some marijuana users) and craving may be more readily evoked or deeply conditioned among some persons than others ("addictive personalities"). Primary methods of assessment of addiction and habituation are completed through clinical interviews or self-report surveys (e.g., American Psychiatric Association DSM-IV, World Health Organization ICD-10). Treatment paradigms for the cessation of addiction begin with initial detoxification or withdrawal, followed by inpatient or outpatient program participation (e.g., 12-step programs, milieu, cognitive-behavioral, or behavioral). Pharmacological efforts (e.g., methadone maintenance) may be used as harm-reduction strategies among those who seem unable to quit drug use.

It is estimated that approximately 15 percent of the world's adults have serious substance abuse problems (not including nicotine addiction), and that this percentage has remained fairly constant over the past twenty-five years. Of these substance abusers, about two-thirds abuse alcohol and one-third abuse other substances, mainly marijuana, amphetamines, cocaine, and heroin. Approximately2.5 percent of the population abuse marijuana, 0.5 percent abuse stimulants, 0.3 percent abuse cocaine or opioids (such as heroin), and up to 0.8 percent abuse other substances (e.g., inhalants, depressants, hallucinogens). Sites of drug production and manufacturing, and distribution routes, tend to identify regions at high risk for abuse.

Drug abuse causes significant health-related consequences and financial losses to legitimate economies. The financial cost to society is estimated to be approximately $600 billion per year worldwide. This does not include the cost of nicotine abuse, which, through its influence on heart disease, lung cancer, chronic obstructive lung disease, and numerous other consequences, is the number one behavioral killer of people worldwide. Drugs of abuse are also associated with the production of psychotic symptoms (e.g., paranoid ideation) and with injuries due to accidents and violence. Approximately 50 percent of automobile fatalities involve alcohol-impaired drivers, and many auto crashes also involve chronic marijuana or amphetamine users.

In addition, each drug class is associated with a unique set of potential consequences. Some drugs of abuse are likely to have lethal consequences (e.g., opiates and depressants), and some have a high potential for addiction. Health consequences can also vary by drug. For example, depressants, PCP, stimulants, steroids, and cannabis are associated with cardiovascular diseases. Stimulant use is linked to seizure, digestion problems, and lung problems. Documented consequences of marijuana use include lung damage and short-term memory problems. Dementia, seizure, memory impairment, central and peripheral nervous systems impairment, gastrointestinal diseases, and cancers of the gastrointestinal tract are all consequences of alcohol consumption. Steroid use is associated with high blood pressure, potential heart attacks, liver tumors, transient infertility, and tendon degeneration. Inhalants are well-known causes of kidney, brain, and liver damage.

The development and maintenance of the addictive process involves multiple pathways and levels of influence within biological, psychological, and sociological domains. Influences exogenous to the individual include environmental, cultural, and social factors. Cultural and social norms, variations in drug use practices, and the values and behaviors of parents, siblings, friends, and role models can all affect an individual's drug experiences. Processes contributing to individual differences in substance use include physiological susceptibility, as measured in genetics studies; affective states; personality; and cognition—including expectancies and memory processes. Substance abuse versus substance use is more strongly related to intra-personal processes (e.g., self-medication for emotional distress) than social processes, although both are influential in the addictive process.