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.
Substance dependence can be diagnosed with physiological dependence, evidence of tolerance or withdrawal, or without physiological dependence.
Commonly abused substances include:
- Opiates and narcotics are powerful painkillers that cause drowsiness (sedation) and sometimes feelings of euphoria. These include heroin, opium, codeine, meperidine (Demerol), hydromorphone (Dilaudid), and oxycodone (Oxycontin).
- Central nervous system (CNS) stimulants include amphetamines, cocaine, dextroamphetamine, methamphetamine, and methylphenidate (Ritalin). These drugs have a stimulating effect, and people can start needing higher amounts of these drugs to feel the same effect (tolerance).
- Central nervous system depressants include alcohol, barbiturates (amobarbital, pentobarbital, secobarbital), benzodiazepines (Valium, Ativan, Xanax), chloral hydrate, and paraldehyde. These substances produce a sedative and anxiety-reducing effect, which can lead to dependence.
- Hallucinogens include LSD, mescaline, psilocybin (“mushrooms”), and phencyclidine (PCP or “angel dust”). They can cause people to see things that aren’t there (hallucinations) and can lead to psychological dependence.
- Tetrahydrocannabinol (THC) is the active ingredient found in marijuana (cannabis) and hashish.