Chemical dependency
| Substance dependence | |
|---|---|
| Classification and external resources | |
| Specialty | Psychiatry |
| ICD-10 | F10.2-F19.2 |
| ICD-9-CM | 303-304 |
| MeSH | D019966 |
Substance dependence also known as drug dependence is an adaptive state that develops from repeated drug administration, and which results in withdrawal upon cessation of drug use. A drug addiction, a distinct concept from substance dependence, is defined as compulsive, out-of-control drug use, despite negative consequences. An addictive drug is a drug which is both rewarding and reinforcing.ΔFosB, a gene transcription factor, is now known to be a critical component and common factor in the development of virtually all forms of behavioral addiction and drug addictions, but not dependence.
Within the framework of the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), substance dependence is redefined as a drug addiction, and can be diagnosed without the occurrence of a withdrawal syndrome. It is now described accordingly: "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."
Withdrawal is the body's reaction to abstaining from a substance upon which a person has developed a dependence syndrome. When dependence has developed, cessation of substance use produces an unpleasant state, which promotes continued drug use through negative reinforcement; i.e., the drug is used to escape or avoid re-entering the associated withdrawal state. The withdrawal state may include physical-somatic symptoms (physical dependence), emotional-motivational symptoms (psychological dependence), or both. Chemical and hormonal imbalances may arise if the substance is not introduced. Psychological stress may also result if the substance is not re-introduced.
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