Substance Dependence

Substance dependence generally refers to drug dependence. It is an adaptive state that results from the long-term abuse of a drug, manifested as a strong psychological and physical desire to repeatedly experience the feelings brought by drugs. Although there are some similar negative effects, substance dependence is a different concept from drug addiction, and the drugs that produce dependence are generally beneficial drugs. From the perspective of molecular biology, current research shows that most of the substance dependence is related to a gene transcription factor called ΔFosB, which is a key component and common factor in the development of dependence phenomena.

Substance dependence was redefined as drug addiction in the fourth edition of the Diagnostic and Statistical Manual of Mental Illness (DSM-IV), and it gives a way to diagnose without the presence of withdrawal syndrome. This method is expressed 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

Common Substance Dependence and Its Characteristics

  • Cocaine addiction

    Cocaine is one of the most addictive substances known. It can directly interfere with the transmission of dopamine in the brain, stimulate the cerebral cortex by regulating the level of dopamine, and generate excitement and joy. Cocaine was used medically as anesthesia, but because it strongly stimulates the nerve center to be excited, it is listed as the main drug list.

  • Amphetamine addiction

    Amphetamine is a chemical substance with a variety of excitatory effects. It is an analog of ephedrine. The first use after synthesis is to replace ephedrine for the treatment of asthma. Amphetamine was one of the most abused stimulants in sports. However, while bringing the championship, amphetamine also caused great harm to the users. The side effects of these drugs are easily addictive. They can also delay the fatigue, make human body be of excessive fatigue without awareness of it, cause some serious diseases and even death.

  • Morphine addiction

    Morphine is an opioid agonist isolated from opium. Its derivative, morphine hydrochloride, is a commonly used anesthetic in clinical practice and has a strong analgesic effect. The biggest disadvantage of morphine is its susceptibility to addiction. This makes long-term user physically or psychologically dependent on morphine, causing severe toxicosis, and leading to great harm to themselves and society.

  • Nicotine addiction

    Nicotine is a neurotoxin that mainly affects the human nervous system. Some smokers subjectively feel that smoking can relieve fatigue and cheer up. This is a transient excitement of the nervous system, and it is actually the euphoria caused by nicotine. After the excitement, the nervous system becomes suppressed. As a result, the sensitivity and accuracy of neuromuscular responses are reduced after smoking. Within 24 hours after stopping smoking, the following discomfort symptoms will appear, such as craving for smoking, irritability, depression, difficulty in concentration, restlessness, headache, lethargy, and gastrointestinal disorders. These are the symptoms of nicotine addiction.

  • Alcohol addiction

    Alcohol is the most widely used addictive substance in the world and penetrates into daily life, as well as socio-economic and cultural activities. Alcohol addiction is also called alcohol dependence. Long-term excessive drinking can cause alcohol abuse and alcohol addiction, and is accompanied by a variety of damage to individuals, family members, and society.

Causes of Substance Dependence

Substance dependence can be divided into psychological dependence and physiological dependence. In the establishment of substance dependence, the neuropeptides corticotrophin releasing factor (CRF) and gene transcription factor cAMP response element binding protein (CREB) play the key role. This process typically occurs in a brain structure called the nucleus accumbens (NAcc). In the NAcc, CREB is activated by cyclic adenosine monophosphate (cAMP) and triggers changes in gene expression that affect proteins such as dynorphin; dynorphin peptides reduce dopamine release into the NAcc by temporarily inhibiting the reward pathway. A sustained activation of CREB thus forces a larger dose to be taken to reach the same effect. This explains the addictive nature of substance dependence.

Prevention of Substance Dependence

Addiction is a complex but treatable condition. As a chronic recurrent disease, addiction may require continuous treatment to increase the interval between relapses and reduce its intensity. The ultimate goal of addiction treatment is to enable individuals to manage their drug abuse behaviors to minimize harm. According to the different conditions of the addict, the treatment plan and the types and dosages of the drugs involved will also vary greatly.

Because the consequences of substance dependence vary, treatment and attitudes toward addiction vary widely in different countries. In the United States and developing countries, the goal of a drug dependence treatment commissioner is generally to ban all drugs altogether. Other countries, particularly in Europe, consider that the goals of treating drug dependence are more complex. Their goals include reducing drug use so that drug use no longer interferes with normal activities, such as work and family commitments, diverting drug users from more dangerous drug injection routes to safer pathways, such as oral intake, reducing crime from drug users, and improving the treatment of other comorbidities, such as AIDS, hepatitis, and mental illness. These results can be achieved without the complete elimination of drug use.


For research use only. Not intended for any clinical use.

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