First, reduced dopamine receptors in the SN are associated with impulsive behavior that has been tied in lab studies to escalating and compulsive self-administration of drugs. 8 This reduction in dopamine receptors has a two-fold impact on addiction. 5 Continued, long-term use also results in the brain reducing the number of dopamine receptors in the brain to adjust for the increased dopamine in the system. 5 Additionally, the intensified dopamine response in the brain that mood-altering drugs produce does not naturally stop once the behavior is initiated or completed (as is the case with natural reward behaviors such as eating or having sex) as a result, cravings for the rewards associated with the drug continue to occur, even during drug use, which leads to compulsive, repetitive use.
5 This association leads to higher and more frequent drug administration in order to experience the pleasure of the reward response more often. Learning has long been understood to be tied to the administration of rewards and punishments, and the intense reward sensation of drug intoxication creates a strong and rapid learning response in the brain, associating drug use with feelings of pleasure. While the intense feelings of pleasure and reward derived from early drug use can play a substantial part in continued use of the drug, it is only a small part of the neurophysiological cycle of addiction. The Brain Following Chronic and Long-Term Substance Abuse 7 The result of this dopamine overflow is the feeling of being high. 5,6 Research has shown that the drugs most commonly abused by humans (including opiates, alcohol, nicotine, amphetamines, and cocaine) create a neurochemical reaction that significantly increases the amount of dopamine that is released by neurons in the brain's reward center. Alcohol and other mood-altering drugs, however, artificially create this effect and do so more efficiently and intensely than natural rewards. 4 The biological purpose for this mechanism is to encourage life-sustaining behaviors (such as eating when hungry) by producing a pleasurable sensation when the necessary behavior happens. 3,4 The neurotransmitter that "unlocks" the electrical stimulation of these areas is dopamine-a neurotransmitter that is strongly associated with feelings of pleasure and reward. The early draw of drug use for most people is the pleasurable feeling they get while "high," 2 a feeling that results from electric stimulation of specific areas of the brain that make up what is collectively called the brain's "reward center": the ventral tegmental area (VTA), nucleus accumbens (NAc), and substantia nigra (SN), all of which are located near the front of the brain. 1 The Brain Following Initial and Early Substance Use Generally, neurons are grouped together based on the neurotransmitters they produce and receive, which is why specific areas of the brain regulate certain functions. While there are many different kinds of neurotransmitters, each neuron is only designed to produce one or two specific types. In order to maintain balance, the brain is able to change these receptor "locks" to fit other neurotransmitters when there is too much, or not enough, of a certain neurotransmitter in the system. Each neurotransmitter is like a key, and it fits into its own specific receptor, which acts like a lock. Neurons absorb these neurotransmitters through receptors. These electrical signals are controlled by chemicals called neurotransmitters, which are secreted from within the neurons and sent out in the brain to other surrounding neurons in order to activate (or deactivate) them. Neurons send electrical signals through your brain and the rest of your nervous system in order to manage everything that happens in the body. In order to carry out all of its necessary functions, from making sure your lungs are breathing to working out a calculus algorithm, the brain uses a complex communication system made up of tree-like cells called neurons. Basics of Brain Function and Neurotransmitters By studying and understanding the biological characteristics of substance dependence, scientists and physicians are able to develop medical and pharmacological treatments that can significantly improve recovery outcomes. Advances in neuroscience and biology have allowed scientists to better understand the physical roots of substance use and dependence, which has led to the contemporary disease model of addiction. Why do people continue to use alcohol and other drugs chronically even after experiencing serious medical, social, legal, or financial consequences? This is a question that has interested professionals in a wide variety of addiction-related fields for many years. Why Do People Use Alcohol & Drugs Even After Facing Consequences?īutler Center for Research | September 1, 2015ĭownload the Drug Abuse, Dopamine, and the Brain's Reward System Research Update.
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