Substance DependenceSubstance Dependence

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Substance dependence, commonly called drug addiction, is a compulsive need to use drugs in order to function normally. When such substances are unobtainable, the user suffers from withdrawal.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), substance dependence is defined as:

When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This, along with Substance Abuse are considered Substance Use Disorders….


Genetic Factors

It has long been established that genetic factors along with social and psychological factors are contributors to addiction. A common theory along these lines is the self-medication hypotheses. Epidemiological studies estimate that genetic factors account for 40–60% of the risk factors for alcoholism. Similar rates of heritability for other types of drug addiction have been indicated by other studies.  Knestler hypothesized in 1964 that a gene or group of genes might contribute to predisposition to addiction in several ways. For example, altered levels of a normal protein due to environmental factors could then change the structure or functioning of specific brain neurons during development. These altered brain neurons could change the susceptibility of an individual to an initial drug use experience. In support of this hypothesis, animal studies have shown that environmental factors such as stress can affect an animal’s genotype.

Overall, the data implicating specific genes in the development of drug dependence is mixed for most genes. One reason this may be the case is due to a focus of current research on common variants. Many addiction studies focus on common variants with an allele frequency of greater than 5% in the general population, however when associated with disease, these only confer a small amount of additional risk with an odds ratio of 1.1-1.3. On the other hand, the rare variant hypothesis states that genes with low frequencies in the population (<1%) confer much greater additional risk in the development of disease.

GWAS studies represent the newest exploration into discovering associations between dependence, addiction, and drug use. These studies employ an unbiased approach to finding genetic associations with specific phenotypes and give equal weight to all regions of DNA, including those with no ostensible relationship to drug metabolism or response. Surprisingly, these studies very infrequently identify genes from proteins previously described via animal knockout models and candidate gene analysis. Instead, large percentages of genes involved in processes such as cell adhesion are commonly identified. This is not to say that previous findings, or the GWAS findings, are erroneous. The important effects of endophenotypes are typically not capable of being captured by these methods. Furthermore, genes identified in GWAS for drug dependence may be involved either in adjusting brain wiring prior to drug experiences, subsequent to them, or both.

Addictive Potential

The addictive potential of a drug varies from substance to substance, and from individual to individual. Dose, frequency, pharmacokinetics of a particular substance, route of administration, and time are critical factors for developing a drug addiction.

An article in The Lancet compared the harm and addiction of 20 drugs, using a scale from 0 to 3 for physical addiction, psychological addiction, and pleasure to create a mean score for addiction. Selected results can be seen in the chart below.Wikipedia narcotic chart

Capture RatesWikipedia narcotic chart

The percentage of users who reported that they had become addicted to their respective drug at some point.

Substance Abuse

Also known as drug abuse, is a patterned use of a substance (drug) in which the user consumes the substance in amounts or with methods which are harmful to themselves or others. The exact cause of substance abuse is impossible to know because there is not just one direct cause. However substance abuse and addiction is known to run in families. One theory suggests there is a genetic disposition which predisposes certain individuals toward substance abuse. Another suggests substance abuse is learned there for people subjected to substance abuse by those around them begin to copy the same behaviors. Substance abuse might start out as a bad habit but when and if addiction develops it manifests as a chronic debilitating disease.

Drug Abuse PictureThe terms have a huge range of definitions related to taking a psychoactive drug or performance enhancing drug for a non-therapeutic or non-medical effect. All of these definitions imply a negative judgment of the drug use in question (compare with the term responsible drug use for alternative views). Some of the drugs most often associated with this term include alcohol, substituted amphetamines, barbiturates, benzodiazepines (particularly alprazolam, temazepam, diazepam and clonazepam), cocaine, methaqualone, and opioids.

Use of these drugs may lead to criminal penalty in addition to possible physical, social, and psychological harm, both strongly depending on local jurisdiction. There are many cases in which criminal or anti-social behavior occur when the person is under the influence of a drug. Long term personality changes in individuals may occur as well. Other definitions of drug abuse fall into four main categories: public health definitions, mass communication and vernacular usage, medical definitions, and political and criminal justice definitions. Substance abuse is prevalent with an estimated 120 million users of hard drugs such as cocaine, heroin, and other synthetic drugs.

Substance abuse is a form of substance-related disorder.

Drug Misuse

Legal drugs are not necessarily safer. A study in 2010 asked drug-harm experts to rank various illegal and legal drugs. Alcohol was found to be the most dangerous by far.

Drug AbuseDrug misuse is a term used commonly when prescription medication with sedative, anxiolytic, analgesic, or stimulant properties are used for mood alteration or intoxication ignoring the fact that overdose of such medicines have serious adverse effects. Prescription misuse has been defined differently and rather inconsistently based on status of drug prescription, the uses without a prescription, intentional use to achieve intoxicating effects, route of administration, co-ingestion with alcohol, and the presence or absence of dependence symptoms. Chronic use leads to a change in the central nervous system which means the patient has developed tolerance to the medicine that more of the substance is needed in order to produce desired effects.When this happens, any effort to stop or reduce the use of this substance would cause withdrawal symptoms to occur.

The rate of prescription drug abuse is fast overtaking illegal drug abuse in the United States. According to the National Institute of Drug Abuse, 7 million people were taking prescription drugs for nonmedical use in 2010. Among 12th graders, prescription drug misuse is now second only to cannabis. “Nearly 1 in 12 high school seniors reported nonmedical use of Vicodin; 1 in 20 reported abuse of OxyContin.”

Avenues of obtaining prescription drugs for misuse are varied: sharing between family and friends, illegally buying medications at school or work, and often “doctor shopping” to find multiple physicians to prescribe the same medication, without knowledge of other prescribers.

substance abuseIncreasingly, law enforcement is holding physicians responsible for prescribing controlled substances without fully establishing patient controls, such as a patient “drug contract.” Concerned physicians are educating themselves on how to identify medication-seeking behavior in their patients, and are becoming familiar with “red flags” that would alert them to potential prescription drug abuse.

As a Value Judgment

Philip Jenkins points out that there are two issues with the term “drug abuse”. First, what constitutes a “drug” is debatable. For instance, GHB, a naturally occurring substance in the central nervous system is considered a drug, and is illegal in many countries, while nicotine is not officially considered a drug in most countries. Second, the word “abuse” implies a recognized standard of use for any substance. Drinking an occasional glass of wine is considered acceptable in most Western countries, while drinking several bottles is seen as an abuse. Strict temperance advocates, who may or may not be religiously motivated, would see drinking even one glass as an abuse. Some groups even condemn caffeine use in any quantity. Similarly, adopting the view that any (recreational) use of marijuana or substituted amphetamines constitutes drug abuse implies a decision made that the substance is harmful, even in minute quantities.

Signs and Symptoms

Depending on the actual compound, drug abuse including alcohol may lead to health problems, social problems, morbidity, injuries, unprotected sex, violence, deaths, motor vehicle accidents, homicides, suicides, physical dependence or psychological addiction.

There is a high rate of suicide in alcoholics and other drug abusers. The reasons believed to cause the increased risk of suicide include the long-term abuse of alcohol and other drugs causing physiological distortion of brain chemistry as well as the social isolation. Another factor is the acute intoxicating effects of the drugs may make suicide more likely to occur. Suicide is also very common in adolescent alcohol abusers, with 1 in 4 suicides in adolescents being related to alcohol abuse. In the USA approximately 30 percent of suicides are related to alcohol abuse. Alcohol abuse is also associated with increased risks of committing criminal offenses including child abuse, domestic violence, rapes, burglaries and assaults.substance abuse pills

Drug abuse, including alcohol and prescription drugs, can induce symptomatology which resembles mental illness. This can occur both in the intoxicated state and also during the withdrawal state. In some cases these substance induced psychiatric disorders can persist long after detoxification, such as prolonged psychosis or depression after amphetamine or cocaine abuse. A protracted withdrawal syndrome can also occur with symptoms persisting for months after cessation of use. Benzodiazepines are the most notable drug for inducing prolonged withdrawal effects with symptoms sometimes persisting for years after cessation of use. Abuse of hallucinogens can trigger delusional and other psychotic phenomena long after cessation of use and cannabis may trigger panic attacks during intoxication and with use it may cause a state similar to dysthymia. Severe anxiety and depression are commonly induced by sustained alcohol abuse which in most cases abates with prolonged abstinence. Even moderate alcohol sustained use may increase anxiety and depression levels in some individuals. In most cases these drug induced psychiatric disorders fade away with prolonged abstinence.

Drug abuse makes central nervous system (CNS) effects, which produce changes in mood, levels of awareness or perceptions and sensations. Most of these drugs also alter systems other than the CNS. Some of these are often thought of as being abused. Some drugs appear to be more likely to lead to uncontrolled use than others.

Traditionally, new pharmacotherapies are quickly adopted in primary care settings; however, drugs for substance abuse treatment have faced many barriers. Naltrexone, a drug originally marketed under the name “ReVia,” and now marketed in intramuscular formulation as “Vivitrol” or in oral formulation as a generic, is a medication approved for the treatment of alcohol dependence. This drug has reached very few patients. This may be due to a number of factors, including resistance by Addiction Medicine specialists and lack of resources.

The ability to recognize the signs of drug use or the symptoms of drug use in family members by parents and spouses has been affected significantly by the emergence of home drug test technology which helps identify recent use of common street and prescription drugs with near lab quality accuracy.


Treatment for substance abuse is critical for many around the world. Often a formal intervention is necessary to convince the substance abuser to submit to any form of treatment. Behavioral interventions and medications exist that have helped many people reduce, or discontinue, their substance abuse.


From the applied behavior analysis literature, behavioral psychology, and from randomized clinical trials, several evidenced based interventions have emerged: behavioral marital therapy, motivational Interviewing, community reinforcement approach, exposure therapy, contingency management.

In children and adolescents, cognitive behavioral therapy (CBT) and family therapy currently have the most research evidence for the treatment of substance abuse problems. These treatments can be administered in a variety of different formats, each of which has varying levels of research support.

Alcoholics Anonymous is one of the most widely known self-help organizations in which members support each other not to use alcohol.

Social skills are significantly impaired in people suffering from alcoholism due to the neurotoxic effects of alcohol on the brain, especially the prefrontal cortex area of the brain. It has been suggested that social skills training adjunctive to inpatient treatment of alcohol dependence is probably efficacious, including managing the social environment.


Pharmacological therapy – A number of medications have been approved for the treatment of substance abuse. These include replacement therapies such as buprenorphine and methadone as well as antagonist medications like disulfiram and naltrexone in either short acting, or the newer long acting form. Several other medications, often ones originally used in other contexts, have also been shown to be effective including bupropion and modafinil.

Methadone and buprenorphine are sometimes used to treat opiate addiction. These drugs are used as substitutes for other opioids and still cause withdrawal symptoms.

Antipsychotic medications have not been found to be useful.

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